Bacteria sentence example
Venter's plan is to use bacteria to brew fuel, much like we brew beer today.
Bacteria can process toxic wastes and oil spills into harmless biodegradable materials.
The airborne bacteria infected all of the people on the trip.
The bacteria, in most cases, have no definite nucleus or central body.
The next time you buy hand soap, try to find the kind that kills bacteria so we can prevent illnesses.Advertisement
They surround individual bacteria, absorb them into their substance, and ultimately destroy them by digestion.
Many bacteria are known which are capable of denitrification, some of them being abundant in fresh dung and upon old straw.
At the same time in Germany, Robert Koch identified the bacteria that caused tuberculosis and the one that caused cholera.
Pasteur first formulated the idea that bacteria are responsible for the diseases of fermented liquids; the corollary of this was a demand for pure yeast.
Bacteria, which are very simple organisms, can be found in every type of ecosystem of the planet.Advertisement
In the first stage the ammonium compounds are oxidized to nitrites by the agency of very minute motile bacteria belonging to the genus Nitrosomonas.
The bacteria that causes rain scald is called Dermatophilus congolensis.
Chalybeate waters, pools in marshes near irons one, &c., abound in bacteria,, some of which belong to the remarkable genera Crenothrix, Cladothrix and Leptothrix, and contain ferric oxide, i.e.
Special wound-cork is also often formed round accidental injuries so as to prevent the rotting of the tissues by the soaking in of rain and the entrance of fungal spores and bacteria.
This property of living substance can be proved in the case of the cells of the higher plants, but it is especially prominent in many of the more lowly organisms, such as the Bacteria.Advertisement
If this is admitted the poverty of tropical sea-water in mineral nitrogen compounds is explained by the higher temperature, which accelerates the activity of denitrifying bacteria.
Phagocytes act as scavengers in ridding the body of noxious particles, and more especially of harmful bacteria.
The bacteria, which are present in almost all soils, enter the root-hairs of their host plants and ultimately stimulate the production of an excrescent nodule, in which they live.
During this period the bacteria multiply and most of them assume a peculiar thickened or branched form, in which state they are spoken of as bacteroids.
The nitrogen-fixing nodule bacteria can be cultivated on artificial media, and many attempts have been made to utilize them for practical purposes.Advertisement
In this manner organisms obtained from red clover can be grown and applied to the seed of red clover; and similar inoculation can be arranged for other species, so that an application of the bacteria most suited to the particular crop to be cultivated can be assured.
Leeuwenhoek, to whom we also owe the discovery of Bacteria and ciliate Infusoria.
Lister put forth similar ideas about the same time; and Billroth came forward in 1874 with the extravagant view that the various bacteria are only different states of one and the same organism which he called Cocco-bacteria septica.
From that time the question of the pleomorphism (mutability of shape) of the bacteria has been hotly discussed; but it is now generally agreed that, while a various forms of bacteria and the and their arrangement.
The most recent works (Vejdovsky, Mend), however, appear to show that nuclei of a structure and mode of division almost typical are to be found in some of the largest bacteria.Advertisement
The plate was then incubated, and, as the figure shows, the bacteria on the C-shaped area were all killed, whereas they developed elsewhere on the plate (traces of the B are just visible to the right) and covered it with an opaque growth.
Similarly nascent methane may reduce iron salts, and the black mud in which these bacteria often occur owes its colour to the FeS formed.
In the deeper parts of this zone the bacteria absorb the SH 2, and, as they rise, oxidize it and store up the sulphur; then ascending into planes more highly oxygenated, oxidize the sulphur to SO 3.
These bacteria therefore employ SH 2 as their respiratory substance, much as higher plants employ carbohydrates - instead of liberating energy as heat by the respiratory combustion of sugars, they do it by oxidizing hydrogen sulphide.
These actions are of extreme importance in nature, as their continuation results in the enormous deposits of bog-iron ore, ochre, and - since Molisch has shown that the iron can be replaced by manganese in some bacteria - of manganese ores.
Considerable advances in our knowledge of the various chromogenic bacteria have been made by the studies of Beyerinck, Lankester, Engelmann, Ewart and others, and have assumed exceptional importance owing to the discovery that Bacteriopurpurin - the red colouring matter contained in certain sulphur bacteria - absorbs certain rays of solar energy, and enables the organism to utilize the energy for its own life-purposes.
Engelmann showed, for instance, that these red-purple bacteria collect in the ultra-red, and to a less extent in the orange and green, in bands which agree with the absorption spectrum of the extracted colouring matter.
Not only so, but the evident parallelism between this absorption of light and that by the chlorophyll of green plants, is completed by the demonstration that oxygen is set free by these bacteria - i.e.
Nitrogen-fixing rhizobium bacteria are located within specially formed cells of legumes such as pea and soybean.
Some bacteria make us ill (Eg salmonella causes food poisoning) but others are harmless.
The lesion of the foot is invaded by bacteria causing it to go septic.
The bacteria can then infect the blood and cause secondary septicemia, which could in turn lead to death without treatment.
Applying it immediately curbs the impulse and neutralizes bacteria and toxins.
The nitrogen in decaying roots, in the dead stems. and leaves of plants, and in humus generally is sooner or later changed into a nitrate, the change being effected by bacteria.
There is also another possible source of loss of nitrates through the activity of denitrifying bacteria.
Certain bacteria of the nitrogenfixing class enter into association with the roots of green plants, the best-known examples being those which are met with in the nodules upon the roots of clover, peas, beans, sainfoin and other plants belonging to the leguminous order.
After the decay of the roots some of the unchanged bacteria are left in the soil, where they remain ready to infect a new leguminous crop.
The method of using them most frequently adopted consists in applying them to the seeds of leguminous plants before sowing, the seed being dipped for a time in a liquid containing the bacteria.
The application of pure cultures of bacteria for improving the fertility of the land is still in an experimental stage.
The view has been put forward that fermentation is due to the activity of bacteria, distinct types occurring in various tobaccos, but the balance of evidence is against it.
They are of importance, since the higher homologues are identical in many cases with the ptomaines produced by the putrefactive action of some bacteria on albumen and other related substances.
But whatever merits they had as clarifiers of turbid water, the advent of bacteriology, and the recognition of the fact that the bacteria of certain diseases may be water-borne, introduced a new criterion of effectiveness, and it was perceived that the removal of solid particles, or even of organic impurities (which were realized to be important not so much because they are dangerous to health per se as because their presence affords grounds for suspecting that the water in which they occur has been exposed to circumstances permitting contamination with infective disease), was not sufficient; the filter must also prevent the passage of pathogenic organisms, and so render the water sterile bacteriologically.
The first filter which was more or less completely impermeable to bacteria was the Pasteur-Chamberland, which was devised in Pasteur's laboratory, and is made of dense biscuit porcelain.
For the sand-filtration of water on a large scale, in which the presence of a surface film containing zooglaea of bacteria is an essential feature, see Water Supply.
As any bacteria present in the milk tend to multiply rapidly on the way to the consumer, it is mainly a question of the time which elapses before consumption.
It is, therefore, further recommended (a) that the milk be rapidly cooled or chilled, as the lower the temperature the less do the bacteria multiply, (b) that contamination during railway transit be avoided by dustproof locked milk cans.
Sterilization then becomes an easier task, the milk drawn under these conditions being very poor in spore-forming bacteria.
It was formerly the custom to include with the Fungi the Schizomycetes or Bacteria, and the Myxomycetes or Mycetozoa; but the peculiar mode of growth and division, the cilia, spores and other peculiarities of the former, and the emission of naked amoeboid masses of protoplasm, which creep and fuse to streaming plasmodia, with special modes of nutrition and spore-formation of the latter, have led to their separation as groups of organisms independent of the true Fungi.
The term Eumycetes is sometimes applied to this group to distinguish them from the Phycomycetes, but as the same name is also applied to the fungi as a whole to differentiate them from the Mycetozoa and Bacteria, the term had best be dropped.
The experiment of Engelmann referred to deserves to be mentioned here, if only in illustration .of the use to which algae have been put in the study of physiological problems. Engelmann observed that certain bacteria were motile only in the presence of oxygen, and that they retained their motility in a microscopic preparation in the neighbourhood of an algal filament when they had come to rest elsewhere on account of the exhaustion of oxygen.
After the bacteria had all been brought to rest by being placed in the dark, he threw a spectrum upon the filament, and observed in what region the bacteria first regained their motility, owing to the liberation of oxygen in the process of carbon-assimilation.
In view of the fact that fresh grape juice contains innumerable bacteria and moulds, in addition to the yeast cells which bring about the alcoholic fermentation, and that the means which are adopted by the brewer and the distiller for checking the action of these undesirable organisms cannot be employed by the wine-maker, it is no doubt remarkable that the natural wine yeast so seldom fails to assert a preponderating action, particularly as the number of yeast cells at the beginning of fermentation is relatively small.
This releases chloric acid, which, being an extremely powerful antiseptic, kills the bacteria to which the ulcers are due.
The minute organisms which are commonly called " bacteria " 1 are also known popularly under other designations, e.g.
All these terms, including the usual one of bacteria, are unsatisfactory; for " bacterium," " bacillus " and " micrococcus " have narrow technical meanings, and the other terms are too vague to be scientific. The most satisfactory designation is that proposed by Nageli in 1857, namely " schizomycetes," and it is by this term that they are usually known among botanists; the less exact term, however, is also used and is retained in this article since the science is commonly known as " bacteriology."
The schizomycetes or bacteria are minute vegetable organisms devoid of chlorophyll and multiplying by repeated bipartitions.
In the two last-mentioned characters and in their manner of division the bacteria resemble Schizophyceae (Cyanophyceae or blue-green algae), and the two groups of Schizophyceae and Schizomycetes are usually united in the class Schizophyta, to indicate the generally received view that most of the typical bacteria have been derived from the Cyanophyceae.
Nor must we overlook the possibility that the endosporeformation in non-motile bacteria more than merely resembles the development of azygospores in the Conjugatae, and some Ulothricaceae, if reduced in size, would resemble them.
The former also looks on the ordinary disjointing bacterial cell as an oidium, and it must be admitted that since Brefeld's discovery of the frequency of minute oidia and chlamydospores among the fungi, the probability that some so-called bacteria - and this applies especially to the branching forms accepted by some bacteriologists - are merely reduced fungi is increased.
That bacteria have existed from very early periods is clear from their presence in fossils; and although we cannot accept all the conclusions drawn from the imperfect records of the rocks, and may dismiss as absurd the statements that geologically immured forms have been found still living, the researches of Renault and van Tieghem have shown pretty clearly that large numbers of bacteria existed in Carboniferous and Devonian times, and probably earlier.
Any liquid (blood, urine, milk, beer, &c.) containing organic matter, or any solid food-stuff (meat preserves, vegetables, &c.), allowed to stand exposed to the air soon swarms with bacteria, if moisture is present and the temperature not ab- Distribu- normal.
Though they occur all the world over in the g Y air and on the surface of exposed bodies, it is not to be supposed that they are by any means equally distributed, and it is questionable whether the bacteria suspended in the air ever exist in such enormous quantities as was once believed.
Cohn's brilliant researches, the chief results of which were published at various periods between 1853 and 1872; Cohn's classification of the bacteria, published in 1872 and extended in 1875, has in fact dominated the study of these organisms almost ever since.
The question of species in the bacteria is essentially the same as in other groups of plants; before a form can be placed in a satisfactory classificatory position its whole lifehistory must be studied, so that all the phases may be known.
In the meantime, while various observers were building up our knowledge of the morphology of bacteria, others were laying the foundation of what is known of the relations of these organisms to fermentation and disease - that ancient will-o'-the-wisp " spontaneous generation " being revived by the way.
The question of the existence of a nucleus in the bacteria is one that has led to much discussion and is a problem of some difficulty.
The high temperature is favourable to the growth of the bacteria but FIG.
Cohn long ago showed that certain glistening particles observed in the cells of Beggiatoa consist of sulphur, and Winogradsky and Beyerinck have shown that a whole series of sulphur bacteria of the genera Thiothrix, Chromatium, Spirillum, Monas, &c., exist, and play important parts in the circulation of this element in nature, e.g.
The purple bacteria have thus two sources of energy, one by the oxidation of sulphur and another by the absorption of " dark rays."
The methods vary much in detail, though in each case the endeavour is to colour the bacteria as deeply, and the tissues as faintly, as possible.
Excess of stain is afterwards removed from the tissues by the use of decolorizing agents, such as acids of varying strength and concentration, alcohol, &c. Different bacteria behave very differently to stains; some take them up rapidly, others slowly, some resist decolorization, others are easily decolorized.
In some instances the stain can be entirely removed from the tissues, leaving the bacteria alone coloured, and the tissues can then be stained by another colour.
In Gram's method, however, only some bacteria retain the stain, while others lose it.
In cultivating bacteria outside the body various media to serve as food material must be prepared and sterilized by heat.
The general principle in their preparation is to supply cutt;va- the nutriment for bacterial growth in a form as nearly g y similar as possible to that of the natural habitat of the organisms - in the case of pathogenic bacteria, the natural fluids of the body.
Cultures are made by transferring by means of a sterile platinum wire a little of the material containing the bacteria to the medium.
In this method the bacteria are distributed in a gelatine or agar medium liquefied by heat, and the medium is then poured out on sterile glass plates or in shallow glass dishes, and allowed to solidify.
Another important method consists in inoculating an animal with some fluid containing the various bacteria.
This method applies especially to pathogenic bacteria whose growth on culture media is slow, e.g.
As our knowledge has advanced it has become abundantly evident that the so-called pathogenic bacteria are not organisms with special features, but that each is a member of a group of organisms possessing closely allied characters.
From the point of view of evolution we may suppose that certain races of a group of bacteria have gradually acquired the power of invading the tissues of the body and producing disease.
In testing the effects of bacteria by inoculation the smaller rodents, rabbits, guinea-pigs, and mice, are usually employed.
The bacteria are mixed with some indifferent fluid, or a fluid culture is employed.
In such diseases the bacteria, when introduced into the subcutaneous tissue, rapidly gain entrance to the blood stream and multiply freely in it, and by means of their toxins cause symptoms of general poisoning.
Various experiments by Schwann, Helmholtz, Schultz, Schroeder, Dusch and others led to the refutation, step by step, of the belief that the more minute organisms, and particularly bacteria, arose de novo in the special cases quoted.
Nevertheless, instances were adduced where the most careful heating of yolk of egg, milk, hay-infusions, &c., had failed, - the boiled infusions, &c., turning putrid and swarming with bacteria after a few hours.
This occurs as a membrane on the surface of the medium, or as irregular clumps or branched masses (sometimes several inches across) submerged in it, and consists of more or less gelatinous matrix enclosing innumerable " cocci," " bacteria," or other elements of the Schizomycete concerned.
The difficult subject of the classification of bacteria dates ' The difficulties presented by such minute and simple organisms as the Schizomycetes are due partly to the few " characters " which they possess and partly to the dangers of error in manipulating them; it is anything but an easy matter either to trace the whole development of a single form or to recognize with certainty any one stage in the development unless the others are known.
To the two divisions of bacteria, Haplobacterinae and Trichobacterinae, must now be added a third division, Myxobacterinae.
Most of the forms in question are found growing on the dung of herbivorous animals, but the bacteria occur not only in the alimentary canal of the animal but also free in the air.
The discoveries that some species of nitrifying bacteria and perhaps pigmented forms are capable of carbon-assimilation, that others can fix free nitrogen and that a number of decompositions hitherto unsuspected are accom fished by Schizomycetes have ut thequestions of P Y Y, P d nutrition and fermentation in quite new lights.
Fischer has proposed that the old division into saprophytes and parasites should be replaced by one which takes into account other peculiarities in the mode of nutrition of bacteria.
The vast majority of bacteria, on the other hand, which are ordinarily termed saprophytes, are saprogenic, i.e.
These forms are termed by Fischer Metatrophic, because they require various kinds of organic materials obtained from the dead remains of other organisms or from the surfaces of their bodies, and can utilize and decompose them in various ways (Polytrophic) or, if monotrophic, are at least unable to work them up. The true parasites - obligate parasites of de Bary - are placed by Fischer in a third biological group, Paratrophic bacteria, to mark the importance of their mode of life in the interior of living organisms where they live and multiply in the blood, juices or tissues.
In effect the urea first becomes carbonate of ammonia by a simple hydrolysis brought about by bacteria, more and more definitely known since Pasteur, van Tieghem and Cohn first described them.
Lea and Miguel further proved that the hydrolysis is due to an enzyme - urase - separable with difficulty from the bacteria concerned.
The excreta of urea alone thus afford to the soil enormous stores of nitrogen combined in a form which can be rendered available by bacteria, and there are in addition the supplies brought down in rain from the atmosphere, and those due to other living debris.
The researches of later years have demonstrated that a still more inexhaustible supply of nitrogen is made available by the nitrogen-fixing bacteria of the soil.
There are in all cultivated soils forms of bacteria which are capable of forcing the inert free nitrogen to combine with other elements into compounds assimilable by plants.
The work of numerous observers has shown that the free nitrogen of the atmosphere is brought into combination in the soil in the nodules filled with bacteria on the roots of Leguminosae, and since these nodules are the morphological expression of a symbiosis between the higher plant and the bacteria, there is evidently here a case similar to the last.
As regards the ammonium carbonate accumulating in the soil from the conversion of urea and other sources, we know from Winogradsky's researches that it undergoes oxidation in two stages owing to the activity of the so-called " nitrifying " bacteria (an unfortunate term inasmuch as " nitrification " refers merely to a particular phase of the cycle of changes undergone by nitrogen).
Winogradsky's investigations resulted in the discovery that two kinds of bacteria are concerned in.
In other words these bacteria can build up organic matter from purely mineral sources by assimilating carbon from carbon dioxide in the dark and by obtaining their nitrogen from ammonia.
It is probable that important consequences of these actions result from the presence of nitrifying bacteria in rotten stone, FIG.
In addition to the bacterial actions which result in the oxidization of ammonia to nitrous acid, and of the latter to nitric acid, the reversal of such processes is also brought about by numerous bacteria in the soil, rivers, &c. Warington showed some time ago that many species are able to reduce nitrates to nitrites, and such reduction is now known to occur very widely in nature.
The researches of Gayon and Dupetit, Giltay and Aberson and others have shown, moreover, that bacteria exist which carry such reduction still further, so that ammonia or even free nitrogen may escape.
Fresh manure abounds in de-nitrifying bacteria, and these organisms not only reduce the nitrates to nitrites, even setting free nitrogen and ammonia, but their effect extends to the undoing of the work of what nitrifying bacteria may be present also, with great loss.
The combined nitrogen of dead organisms, broken down to ammonia by putrefactive bacteria, the ammonia of urea and the results of the fixation of free nitrogen, together with traces of nitrogen salts due to meteoric activity, are thus seen to undergo various vicissitudes in the soil, rivers and surface of the globe generally.
In ordinary arable soil there exist motile rod-like bacteria, Bacterium radicicola.
In the cells of the nodule the bacteria multiply and develop, drawing material from their host.
Many of the bacteria exhibit curious involution forms (" bacteroids "), which are finally broken down and their products absorbed by the plant.
Inside the hair the bacteria are pushing their way up in a thin stream.
The green plant, however, always keeps the upper hand, restricting the development of the bacteria to the nodules and later absorbing them for its own use.
The important part that these bacteria play in agriculture led to the introduction in Germany of a commercial product (the socalled " nitragin ") consisting of a pure culture of the bacteria, which is to be sprayed over the soil or applied to the seeds before sowing.
Another important advance is in our knowledge of the part played by bacteria in the circulation of carbon in nature.
The work of van Tieghem, van Senus, Fribes, Omeliansky and others has now shown that while certain anaerobic bacteria decompose the substance of the middle lamella - chiefly pectin compounds - and thus bring about the isolation of the cellulose fibres when, for instance, flax is steeped or " retted," they are unable to attack the cellulose itself.
There exist in the mud of marshes, rivers and cloacae, &c., however, other anaerobic bacteria which decompose cellulose, probably hydrolysing it first and then splitting the products into carbon dioxide and marsh gas.
Beyerinck and Jegunow have shown that some partially anaerobic sulphur bacteria can only exist in strata at a certain depth below the level of quiet waters where SH 2 is being set free below by the bacterial decompositions of vegetable mud and rises to meet the atmospheric oxygen coming down from above, and that this zone of physiological activity rises and falls with the variations of partial pressure of the gases due to the rate of evolution of the SH 2.
Beyerinck has shown that Spirillum desulphuricans, a definite anaerobic form, attacks and reduces sulphates, thus undoing the work of the sulphur bacteria as certain de-nitrifying bacteria reverse the operations of nitro-bacteria.
The most recent observations of Molisch seem to show that bacteria possessing bac eriopurpurin exhibit a new type of assimilation - the assimilation of organic material under the influence of light.
In the case of these red-purple bacteria the colouring matter is contained in the protoplasm of the cell, but in most chromogenic bacteria it occurs as excreted pigment on and between the cells, or is formed by their action in the medium.
Milk is a medium not only admirably suited to the growth of bacteria, but ry Y Y g as a matter of fact, always contaminated with these organisms in the ordinary course of supply.
Quite distinct is the search for the germs which cause undesirable changes, or " diseases "; and great strides have been made in discovering the bacteria concerned in rendering milk " ropy," butter " oily " and " rancid," &c. Cheese in its numerous forms contains myriads of bacteria, and some of these are now known to be concerned in the various processes of ripening and other changes affecting the product, and although little is known as to the exact part played by any species, practical applications of the discoveries of the decade 1890-1900 have been made, e.g.
The suggestion that it is due to the oxidation of a body excreted by the bacteria seems answered by the failure to filter off or extract any such body.
If then we prepare densely inseminated plates of these two bacteria in gelatine food-medium to which starch is added as the only carbohydrate, the bacteria grow but do not phosphoresce.
It is these bacteria which form the zoogloea of the " mother of vinegar," though this film may contain other organisms as well.
The idea that this film of bacteria oxidizes the alcohol beneath by merely condensing atmospheric oxygen in its interstices, after the manner of spongy platinum, has long been given up; but the explanation of the action as an incomplete combustion, depending on the peculiar respiration of these organisms - much as in the case of nitrifying and sulphur bacteria - is not clear, though the discovery that the acetic bacteria will not only oxidize alcohol to acetic acid, but further oxidize the latter to CO 2 and 01-1 2 supports the view that the alcohol is absorbed by the organism and employed as its respirable substance.
Promise of more light on these oxidation fermentations is afforded by the recent discovery that not only bacteria and fungi, but even the living cells of higher plants, contain peculiar enzymes which possess the remarkable property of " carrying " oxygen - much as it is carried in the sulphuric acid chamber - and which have therefore been termed oxydases.
Much as the decade from 1880 to 1890 abounded with investigations on the reactions of bacteria to heat, so the following decade was remarkable for discoveries regarding the effects of other forms of radiant energy.
The observations Bacteria g 5' of Downes and Blunt in 1877 left it uncertain whether the bactericidal effects in broth cultures exposed to solar rays were due to thermal action or not.
The practical effect of the bactericidal action of solar light is the destruction of enormous quantities of germs in rivers, the atmosphere and other exposed situations, and experiments have shown that it is especially the pathogenic bacteria - anthrax, typhoid, &c. - which thus succumb to lightaction; the discovery that the electric arc is very rich in bactericidal rays led to the hope that it could be used for disinfecting purposes in hospitals, but mechanical difficulties intervene.
Even when the light is not sufficiently intense, or the exposure is too short to kill the spores, the experiments show that attenuation of virulence, That bacterial fermentations are accompanied by the evolution of heat is an old experience; but the discovery that the " spontaneous " combustion of sterilized cotton-waste does not occur simply if moist and freely exposed to oxygen, philous bacteria.
Apart from the resolution of doubts as to the power of spores to withstand such temperatures for long periods, the discoveries of Miguel, Globig and others have shown that there are numerous bacteria which will grow and divide at such temperatures, e.g.
This phenomenon is due to the activity of a whole series of marine bacteria of various genera, the examination and organisms depend on the discovery that their patho genicity or virulence can be modified - diminished or increased - by definite treatment, and, in the natural course of epidemics, by alterations in the environment.
These facts, and the further knowledge that many bacteria never observed as parasites, or as pathogenic forms, produce toxins or poisons as the result of their decompositions and fermentations of organic substances, have led to important results in the applications of bacteriology to medicine.
Saprophytic bacteria can readily make their way down the dead hypha of an invading fungus, or into the punctures made by insects, and Aphides have been credited with the bacterial infection of carnations, though more recent researches by Woods go to show the correctness of his conclusion that Aphides alone are responsible for the carnation disease.
On the other hand, recent investigation has brought to light cases in which bacteria are certainly the primary agents in diseases of plants.
The principal features are the stoppage of the vessels and consequent wilting of the shoots; as a rule the cut vessels on transverse sections of the shoots appear brown and choked with a dark yellowish slime in which bacteria may be detected, e.g.
If the recent work on the cabbage disease may be accepted, the bacteria make their entry at the water pores at the margins of the leaf, and thence via the glandular cells to the tracheids.
Little is known of the mode of action of bacteria on these plants, but it may be assumed with great confidence that they excrete enzymes and poisons (toxins), which diffuse into the cells and kill them, and that the effects are in principle the same as those of parasitic fungi.
As we have seen, thermophilous bacteria can grow at high temperatures, and it has long been known that some forms develop on ice.
Astonishment has been frequently expressed at the powerful activities of bacteria - their rapid growth and dissemination, of the extensive and profound decompositions and Activity bacteria.
In the first place, the extremely small size and isolation of the vegetative cells place the protoplasmic contents in peculiarly favourable circumstances for action, and we may safely conclude that, weight for weight and molecule for molecule, the protoplasm of bacteria is brought into contact with the environment at far more points and over a far larger surface than is that of higher organisms, whether - as in plants - it is distributed in thin layers round the sap-vacuoles, or - as in animals - is bathed in fluids brought by special mechanisms to irrigate it.
The demonstration by Pasteur that definite diseases could be produced by bacteria, proved a great stimulus to research in the etiology of infective conditions, and the result Historical was a rapid advance in human knowledge.
By means of these the modes of cultivation, and especially of separation, of bacteria were greatly simplified.
By 1876 the anthrax bacillus had been obtained in pure culture by Koch, and some other pathogenic bacteria had been observed in the tissues, but it was in the decade 1880-1890 that the most important discoveries were made in this field.
Immunity against diseases caused by bacteria has been the subject of systematic research from 1880 onwards.
The modes by which bacteria produce their effects also became a subject of study, and attention was naturally turned to their toxic products.
It may be noted, however, that it is still doubtful whether this organism is to be placed amongst the bacteria or amongst the protozoa.
The methods employed in studying the relation of bacteria to disease are in principle comparatively simple,but considerable experience and great care are necessary in applying them and in interpreting results.
It is to be noted that in the case of bacteria we can only judge of organisms being of different species by the stability of the characters which distinguish them, and numerous examples might be given where their characters become modified by comparatively slight change in their environment.
Some, however - the strictly anaerobic bacteria - grow only in the absence of oxygen; hence means must be adopted for excluding this gas.
The various tissues affected are examined microscopically and cultures made from them; in this way the structural changes and the relation of bacteria to them can be determined.
Methods have been introduced for the purpose of breaking up the bodies of bacteria and setting free the intracellular toxins.
And although effects may some times be produced in a mechanical manner by bacteria plugging capillaries of important organs, e.g.
Here, just as in the general subject of fermentation, we must inquire whether the bacteria form the substances in question directly or by means of non-living ferments or enzymes.
In many cases, however, the filtrate, when injected, produces comparatively little effect, whilst toxic action is observed when the bacteria in a dead condition are used; this is the case with the organisms of tubercle, cholera, typhoid and many others.
The toxins are here manifestly contained within the bodies of the bacteria, i.e.
In other words, the toxins of different bacteria are closely similar in their results on the body and the features of the corresponding diseases are largely regulated by the vital properties of the bacteria, their distribution in the tissues, &c. The distinction between the two varieties of toxins, though convenient.
This, for example, is the case with the anthrax bacillus; although the effect of this organism in the living body indicates the production of toxins which diffuse for a distance around the bacteria.
Fluid containing these aggressins greatly increases the toxic effect of the corresponding bacteria, and may produce death at an earlier stage than ever occurs with the bacteria alone.
Not only are the general symptoms of poisoning in bacterial disease due to toxic substances, but also the tissue changes, many of them of inflammatory nature, in the neighbourhood of the bacteria.
Brieger, in his earlier work, found that alkaloids were formed by bacteria in a variety of conditions, and that some of them were poisonous.
We shall now consider how bacteria may behave when they have gained entrance to the body, what effects may be produced, and what circumstances may modify the disease in any particular case.
Thus in cholera the bacteria are practically confined to the intestine, in diphtheria to the region of the false membrane, in tetanus to some wound.
In the lastmentioned disease even the local multiplication depends upon the presence of other bacteria, as the tetanus bacillus has practically no power of multiplying in the healthy tissues when introduced alone.
In short, if we place aside the outstanding exception of tumour growth, we may say that practically all the important phenomena met with in disease may be experimentally produced by the injection of bacteria or of their toxins.
In health the blood and internal tissues are bacterium-free; after death they offer a most suitable pabulum for various bacteria; but between these two extremes lie states of varying liability to infection.
The circumstances which alter the virulence of bacteria will be referred to again in connexion with immunity, but it may be stated here that, as a general rule, the virulence of an organism towards an animal is increased by sojourn in the tissues of that animal.
In the first - active immunity - a reaction or series of reactions is produced in the body of the animal, usually by injections of bacteria or their products.
Of the chief methods used in producing active immunity the first is by inoculation with bacteria whose virulence has been diminished, i.e.
The development of anti-substances is, however, not peculiar to bacteria, but occurs also when alien cells of various kinds, proteins, ferments, &c., are injected.
The antigens, as already indicated, may occur in bacteria, cells, &c., or they may occur free in a fluid.
In preparing anti-bacterial sera the lines of procedure correspond to those followed in the case of antitoxins, but the bacteria themselves in the living or dead condition or their maceration products are always used in the injections.
Furthermore, lysogenic action is not confined to the case of bacteria but obtains also with other organized structures, e.g.
As regards the mode of action of agglutinins, Gruber and Durham considered that it consists in a change in the envelopes of the bacteria, by which they swell up and become adhesive.
The phenomenon of agglutination depends essentially on the union of molecules in the bacteria - the agglutinogens - with the corresponding agglutinins, but another essential is the presence of a certain amount of salts in the fluid, as it can be shown that when agglutinated masses of bacteria are washed salt-free the clumps become resolved.
The number of bacteria contained within a number of, say fifty, leucocytes can be counted and the average taken.
The average number of bacteria contained within leucocytes in the case tested, divided by the number given by the normal serum, is called the phagocytic index.
The destruction of bacteria by direct cellular agency both in natural and acquired immunity must not be overlooked.
The increased ingestion of bacteria in active immunity would seem to depend upon the presence of immune opsonins in the serum.
Thus the apparent increased activity of the leucocytes is due to a preliminary effect of the opsonins on the bacteria.
While in immunity there probably occurs no marked change in the leucocytes themselves, it must be admitted that the increased destruction of bacteria by these cells is of the highest importance.
Then as regards natural powers of destroying bacteria, phagocytosis aided by chemiotaxis plays a part, and it can be understood that an animal whose phagocytes are attracted by a particular bacterium will have an advantage over one in which this action is absent.
Whether bacteria will be destroyed or not after they have been ingested by the leucocytes will depend upon the digestive powers of the latter, and these probably vary in different species of animals.
The blood serum has a direct bactericidal action on certain bacteria, as tested outside the body, and this also varies in different animals.
He also showed that the development of artificial immunity is attended by the appearance of phagocytosis; also, when an anti-serum is injected into an animal, the phagocytes which formerly were indifferent might move towards and destroy the bacteria.
Later observers have found similar occurrences in the cases of small nematodes, rotifers and bacteria.
Quinine has considerable powers as an .antiseptic, this term defined for some time as indicating the power to kill bacteria.
Against the bacteria quinine is not at all an exceptionally powerful antiseptic, though more powerful than carbolic acid.
Many bacteria are killed by a 2 solution of the alkaloid.
The explanation that this influence on the leucocytes explained the favourable action of quinine on certain inflammatory processes no longer holds, since we know that the inflammatory conditions are of microbic origin, and that the movements of the leucocytes are not objectionable, but highly desirable as a means of defence against bacteria and their products.
Following upon Dr Koch's discovery of a method of isolating bacteria, and of making approximate determinations of their number in any volume of water, a most remarkable diminution in the number of microbes contained in sand-filtered water was observed; and it is now well known that when a properly.
Even yet medical science has not determined the effect upon the human system of water highly charged with bacteria which are not known to be individually pathogenic. In the case of the bacilli of typhoid and cholera, we know the direct effect; but apart altogether from the presence of such specific poisons, polluted water is undoubtedly injurious.
This course can scarcely fail to introduce into the sand many bacteria, which may be washed through when the full working of the filters is begun; and it should not, therefore, be adopted when the source of the supply is known to be subject to human pollution.
Sand filtration, even when working in the best possible manner, falls short of the perfection necessary to prevent the passage of bacteria which may multiply after the filter is passed.
It is therefore natural that attempts should have been made to construct filters which, while permitting the slow percolation of water, should preclude the passage of bacteria or their spores.
Attempts have been made, by adding certain coagulants to the water to be filtered, to increase the power of sand and other granular materials to arrest bacteria when passing through them at much higher velocities than are possible for successful filtration by means of the surface film upon sand.
This, when attained, is undoubtedly a most important reduction in the chance of pathogenic bacteria passing into the filtered water; but much mere must be done than has hitherto in most places been done to ensure the constancy of such a condition before it can be assumed to represent the degree of safety attained.
Subjection to the temperature of boiling water for, say, half an hour seemed an efficient mode of sterilization, until it was discovered that the spores of bacteria are so involved in heat-resisting membranes, that only prolonged exposure to dry, baking heat can be recognized as an efficient process of sterilization.
Moreover, the presence of bacteria, or their spores, is so universal that only extreme precautions guard against a re-infection of the sterilized material.
But it undoubtedly prolongs life, lessens suffering, and by checking the growth of bacteria upon the cancer reduces the fetid odour and the symptoms of septic intoxication.
The first evidence for the existence of Palaeozoic Bacteria was obtained in 1879 by Van Tieghem, who found that in silicified vegetable remains from the Coal Measures of St Etienne Bacteria.
Since that time a number of fossil Bacteria, mainly from Palaeozoic strata, have been described by Renault, occurring in all kinds of fossilized vegetable and animal debris.
On the whole, the occurrence of Bacteria in Palaeozoic times - so probable a priori - may be taken as established, though the attempt to discriminate species among them is probably futile.
In English-speaking countries, and by the majority of German writers, the meaning is now restricted to the study of the action of chemical substances (as apart from foods) on all kinds of animals, from bacteria up to man; it is, in fact, a comparative study of the action of chemical bodies on invertebrate and vertebrate animals.
The methods of research are essentially those employed by physiologists, the action of substances being studied in the usual way on bacteria, leucocytes, frogs, rabbits and other animals.
Locally their destructive and irritating effects vary a good deal, but even when very dilute they all have a marked poisonous action on bacteria, white blood corpuscles, yeast and similar organisms. After absorption most of them exercise a depressing effect upon the nervous system, and are capable of reducing high temperature.
The doctor said it was beneficial bacteria.
Bacteria enter through skin abrasions or via eyes, nose or mouth.
In these classes most of the bacteria you see will be grown either on nutrient agar or on blood agar.
The gaskets keep the containers airtight and prevent the baby food becoming contaminated with bacteria, molds or insects.
The ' special ' biochemical adaptations used by bacteria that oxidize ammonia or nitrite.
Many bacteria may however grow in both the presence or absence of oxygen, and these are termed facultative anaerobes.
The cage is certainly readily penetrated by soil (as dust particles) containing virus, bacteria and fungi along with soil arthropods.
The ingredients act on bacteria and fungi, is kind to sensitive skin and mildly astringent.
The bacteria were shown to spread via the bloodstream from the mouth to the major blood vessels where they caused accelerated atherosclerosis.
Whether spots or stripes form, according to the model, depends on the level of response of the bacteria to the chemical attractant.
Many bacteria can be found within rice, and the most common bacteria associated with food poisoning from rice is called bacillus.
Living in the soil are huge numbers of bacteria belonging to the genus bacillus.
Modified bacterial viruses, called bacteriophages, are used to deliver the gene encoding this protein to specific harmful bacteria.
Delbrueck chose to use bacteriophage, viruses that infect bacteria and then can multiply very rapidly.
Q. What temperature should I wash my baby bed linen in to kill bacteria?
It contains berberine, an alkaloid that may prevent UTIs by inhibiting bacteria from adhering to the wall of the urinary bladder.
It is capable of repelling bacteria and other microbes, releases a biocide and can also remove the organism on contact.
Ozone is a natural biocide, which effectively kills bacteria, viruses and fungi within seconds.
Workers cleaning towers must have protective clothing and respirators to protect them from both bacteria and chlorine (or other biocides ).
This bacteria can also cause blood poisoning (septicaemia) if it invades the bloodstream.
It could also enables bacteria which cause the disease botulism to develop.
These bacteria produce a toxin in food which causes a severe illness called botulism which can be fatal.
These areas become infected with anaerobic bacteria, which release malodorous volatile fatty acids as a metabolic byproduct.
Lactoferrin also disrupts the process by which bacteria digest carbohydrates, further limiting their growth.
Roots and bacteria also excrete natural chelates to improve the intake of iron.
The enzyme DMSP-lyase, found in algae and some bacteria, mediates the cleavage of DMSP to DMS and acrylic acid.
The daily rhythm of life is maintained by a circadian clock in organisms ranging from bacteria to humans.
Our general interest is in the mechanisms of energy conservation in bacteria.
Strict codes are in place to prevent contamination of Martian soil with Earth bacteria.
Penicillin does not really damage existing bacteria, but when the bacteria divide to make new cells, a new wall cannot cross-link properly.
Biological control can include choosing resistant turf grass cultivars or using soil bacteria to help improve the turf grasses ' health.
Your body has defenses to prevent bacteria from causing cystitis.
Bacteria and bugs often get a bad press causing food poisoning, stomach bugs, travelers diarrhea and so on.
Use a broad-spectrum disinfectant active against viruses, bacteria, fungi and other pathogen organisms (Virkon® S ).
By the very nature of the flower waters, (being a pure distillate ), they are not ' bacteria friendly ' .
Whether due to viruses or bacteria, the infection is spread from person to person by airborne droplets, hand contact or kissing.
The bacteria that cause TB are inhaled in the form of microscopic droplets that come from a person infected with TB.
The pathogens include bacteria which cause dysentery, viruses responsible for polio and hepatitis, and many others.
Only a few genera of bacteria such as Bacillus and Clostridium are capable of forming endospores.
Peroxisomes - derived from rough eroxisomes - derived from rough ER, that contain enzymes that will form hydrogen peroxide - which phagocytic cells use to kill bacteria.
There were already strains of bacteria that were becoming resistant to penicillin, so the arrival of the new antibiotic erythromycin was much welcomed.
Classification of fluorescent soft rot Pseudomonas bacteria, including P. marginalis strains, using whole cell fatty acid analysis.
Bacteria and tiny flagellates are pulled down toward the vacuoles by this flow.
These bacteria are often also referred to as the ' gut flora ' .
The toxic products of dead tissue and bacteria diffuse out of the apical foramen of the tooth root into the periodontal ligament.
We have used fresh garlic, cinnamon, clove oil, lavender oil successfully with bacteria.
Because the symptoms are quite similar to acute and chronic bacterial gastroenteritis of ferrets, stool samples need to be cultured for these bacteria.
I seem to recall bacteria, traces of Matthew Kelly's shaven beard, a live baby gecko all being found in the burgers.
Main research interests are the molecular typing of bacteria and characterisation of antibiotic resistance genes.
If we find some really good bacteria then we can use germ warfare to help prevent these diseases.
Usually yeasts are grown on yeast glucose agar, other fungi on malt agar and bacteria on nutrient agar.
The bacteria can enter the skin through cuts and abrasions and can produce granulomas around some of the joints.
The large amounts of ammonia in the slurry become breeding ground for bacteria, which turn it into acid.
Peruvian guano was a potent nitrogenous fertilizer and likely to be an abundant source of toxin-producing bacteria.
Poor personal hygiene and infected food handlers Poor personal hygiene can result in food becoming contaminated with bacteria.
Does not contain any enzymes, bacteria or microorganisms which may be considered environmentally hazardous.
They are in fact, more complex structures involving a honeycomb of cracks and crevices in which bacteria thrive.
Peroxisomes - derived from rough ER, that contain enzymes that will form hydrogen peroxide - which phagocytic cells use to kill bacteria.
In the alkaline environment of the urine, arbutin is converted into another chemical, called hydroquinone, which kills bacteria.
The required bacteria are acquired by hatchlings by eating the feces of adult iguanas.
Even at 15 min, Virkon S is still able to significantly lower the titer of the contaminating bacteria by at least 10 6.5.
Lymph nodes filter lymph nodes filter lymph fluid, and thus bacteria, viruses and other foreign substances are removed.
They aimed to engineer the bacteria to contain a switch governing their sensitivity to the sugar maltose.
They target HIV because the virus is coated with the sugar mannose, which the bacteria use as a food source.
Bacteria causing contagious mastitis are spread from infected quarters to other healthy quarters of the same or other cows.
What causes meningitis Meningitis is usually caused by a bacteria or a virus.
Organic deposits forms thick layers on the bottom, eventually metamorphosed by anaerobic bacteria and then pressure to yield hydrocarbons.
Probiotic bacteria modulate the immune system and provide an ecological balance in the gut that excludes disease-causing microbes.
This destroys all bacteria in the milk and makes it last much longer than ordinary pasteurized milk.
A highly motile organism, the colonies are surrounded by wispy swarms of bacteria.
The goblet cells and the glands constantly secrete mucous, which serves to moisten the inhaled air and trap dust and bacteria.
Tuberculosis is a disease caused by an infection with the bacteria mycobacterium tuberculosis.
In MS, the body's immune system attacks myelin as if it were an invading bacteria or virus.
Avoid the animal's breath, as it may carry some potentially nasty bacteria.
Denitrification filters convert nitrate to nitrogen gas, the bacteria in such filters are anaerobic.
These device relies bacteria living on balls of Sulfur to remove nitrate from the water.
Other bacteria in a mature aquarium convert the nitrite to nitrate.
The ammonia produced by the fish is acted upon in mature water by the bacteria, which converts it to another compound called nitrite.
Around 5% of clinically normal women have colonization of the bacteria in their vaginas.
Bacteria Bacteria are tiny, single-celled organisms that live in the body.
During this testing, the concentrate was inoculated with 30 known spoilage organisms and bacteria.
Bacteria start to multiply within the blockage, which leads to inflammatory lesions or red papules.
Bacteria phage were found to transfer genes between Erwinia species  .
These bacteria can cause a reoccurring cough, which produces phlegm, often blood stained.
Of the photosynthetic bacteria, three schemes are used for light harvesting pigments.
One million bacteria, clumped together, would cover a pinhead.
Bacteria use the same or similar mechanisms in order to induce actin polymerization.
Bacteria on a surface produce sugary compounds called polysaccharides, which form a thick coating on the surface called the glycocalyx.
In dry conditions on the leaf surface clusters of bacteria are found encapsulated in extracellular polysaccharide.
As the names suggest, bacterial prostatitis is caused by bacteria, whereas with non-bacterial prostatitis, no bacteria are present.
Some oils actually inhibit airborne bacteria, thus purifying the air in a sickroom.
The purple bacteria evolved oxygen respiration by reversing the flow of molecules through their carbon fixing pathways and modifying their electron transport chains.
And the exploration of space might be a waste of gasoline, frog after-taste pills, truth serum and re-location papers for suspicious bacteria.
There is also a useful diagram showing how bacteria cause peptic ulcers.
When we eat anything sugary, the plaque bacteria turn the sugar into the energy they need, producing acid at the same time.
It is now clear that marine bacteria have long been in mutualistic symbiosis with marine animals.
Bacteria getting into the body through a wound, or through injecting drugs cause tetanus.
A ring of chemotactic bacteria moves away from a central disk of agarose containing toluene.
Probiotics and Beneficial Bacteria Researchers estimate that more than 400 species of bacteria inhabit the digestive tract.
Gram negative bacteria have evolved a number of different protein translocation pathways across the outer membrane.
I. Screening of activity to bacteria, fungi and American trypanosomes of 13 native plants.
This family of bacteria has been responsible for many of the most serious outbreaks of drug-resistant tuberculosis.
Tuberculosis is a disease caused by an infection with the bacteria Mycobacterium tuberculosis is a disease caused by an infection with the bacteria Mycobacterium tuberculosis.
Bacteria present on the cow's udders or on equipment may get into raw milk.
The cow's physiology is stressed, and when bacteria do enter the udder, mastitis is likely.
When conditions of moisture, temperature, and food supply became unfavorable, many soil bacteria would form resistant spores.
The microorganisms or bacteria that produce urease are enzymes.
The bacteria that commonly cause urethritis in men can cause serious problems in women.
Glanders is a very virulent, infectious disease spread by bacteria.
You can improve the benefit of using brewer's yeast by eating cultured yogurt or supplement good bacteria capsules between meals.
Probiotic yogurts Do the bacteria in these yogurts really help your gut?
The beginning of definite knowledge on the phenomenon of fermentation may be dated from the time of Antony Leeuwenhoek, who in 1680 designed a microscope sufficiently powerful to render yeast cells and bacteria visible; and a description of these organisms, accompanied by diagrams, was sent to the Royal Society of London.
About this time Hansen, who had long been engaged in researches on the biology of the fungi of fermentation, demonstrated that yeast free from bacteria could nevertheless occasion diseases in beer.
This discovery was of great importance to the zymo-technical industries, for it showed that bacteria are not the only undesirable organisms which may occur in yeast.
Having found that some of the commonest diseases of beer, such as yeast turbidity and the objectionable changes in flavour, were caused not by bacteria but by certain species of yeast, and, further, that different species of good brewery yeast would produce beers of different character, Hansen argued that the pitching yeast should consist only of a single species - namely, that best suited to the brewery in question.
Lister determined the number of bacteria present in a drop of the liquid under examination by counting, and then diluted this with a sufficient quantity of sterilized water so that each drop of the mixture should contain, on an average, less than one bacterium.
He introduced bacteria into liquid sterile nutrient gelatin.
It is beyond the scope of the present article to attempt to describe the different forms of budding fungi (Saccharomyces), mould fungi and bacteria which are capable of fermenting sugar solutions.
These end-organs are the active agents in taking up foreign granules, or bacteria, which may have found their way into the fluid of the body-cavity.
Some are true germicides, capable of destroying the bacteria, whilst others merely prevent or inhibit their growth.
For the growth of bacteria there must be a certain food supply, moisture, in most cases oxygen, and a certain minimum temperature (see Bacteriology).
In early inquiries a great point was made of the prevention of putrefaction, and work was done in the way of finding how much of an agent must be added to a given solution, in order that the bacteria accidentally present might not develop. But for various reasons this was an inexact method, and to-day a