Lister for isolating a pure culture of lactic acid bacterium.
The first class include such changes as the alcoholic fermentation of sugar solutions, the acetic acid fermentation of alcohol, the lactic acid fermentation of milk sugar, and the putrefaction of animal and vegetable nitrogenous matter.
The Bacterium acidi lacti described by Pasteur decomposes milk sugar into lactic acid.
Sodium amalgam or zinc and hydrochloric acid reduce it to lactic acid, whilst hydriodic acid gives propionic acid.
For he proved that the various changes occurring in the several processes of fermentation - as, for example, in the vinous, where alcohol is the chief product; in the acetous, where vinegar appears; and in the lactic, where milk turns sour - are invariably due to the presence and' growth of minute organisms called ferments.
Lactic acid and alanine were shown to be oxyand amino-propionic acids respectively; glycollic acid and glycocoll, oxyand amino-acetic acids; salicylic and benzamic acids, oxyand amino-benzoic acids.
Glucose also undergoes fermentation into lactic acid in the presence of the lactic acid bacillus, and into butyric acid if the action of the preceding ferment be continued, or by other bacilli.
It also yields, by the so-called mucous fermentation, a mucous, gummy mass, mixed with mannitol and lactic acid.
Massart and Bordet, Leber, Metchnikoff and others have studied the phenomenon in leucocytes, with the result that while there is evidence of their being positively chemiotactic to the toxins of many pathogenic microbes, it is also apparent that they are negatively influenced by such substances as lactic acid.
It is difficultly fermented by yeast, but readily by the lactic acid bacillus.
Lactic Acid >>
The lactic acid bacillus, always present in unboiled milk (to which the souring of milk is due), is easily destroyed by heat; but the bacillus mesentericus, often found in it, forms spores, which are not destroyed by ordinary boiling, and germinate when the milk is kept at a moderately warm temperature, producing a brisk fermentation whereby a large volume of gas is liberated.
Since Metchnikoff's introduction (see Longevity) of the use of soured milk for dietetic purposes-the lactic acid bacillus destroying pathogenic bacteria in the intestine-a great impetus has been given to the multiplication of laboratory preparations containing 'cultures of the bacillus; and in recent years much benefit to health has, in certain cases, been derived from the discovery.
In 1780 he proved that the acidity of sour milk is due to what was afterwards called lactic acid; and by boiling milk sugar with nitric acid he obtained mucic acid.
The neuron is described as having a cell body or perikaryon from which the cell branches - dendrites and axon - extend, and it is this perikaryon which, as its name implies, muscle produces lactic acids during activity, it has been suggested that acids are among the "fatigue substances" with which muscle poisons itself when deprived of circulating blood.
The oxidation of the glycols led him to homologues of lactic acid, and a controversy about the constitution of the latter with H.
In the remedy just mentioned the salicylic acid forms the basis; but sometimes chloride of zinc or lactic acid is added to it to make it act more quickly, and these are the adjuvants.
It may be diminished or its increase prevented by a diet from which red meat and meat extracts are excluded, by the use of the lactic acid bacillus, by the administration of laxatives and cholagogues to regulate the bowels, and by the use of iodides and nitrites.
To these injurious microbes Metchnikoff has given the name of "wild," and he proposes to restore health by giving "tame" microbes, such as lactic acid bacilli.
The lactic acid bacilli are given either in the form of tablets or milk soured by them, or cheese made from the sour milk.
When Pasteur in 1857 showed that the lactic fermentation depends on the presence of an organism, it was already known from the researches of Schwann (1837) and Helmholtz (1843) that fermentation and putrefaction are intimately connected with the presence of organisms derived from the air, and that the preservation of putrescible substances depends on this principle.
Bacillus chauvaei ferments cane-sugar solutions in such a way that normal butyric acid, inactive lactic acid, carbon dioxide, and FIG.
Pictet, Vegetable Opium also contains a gum, pectin, a wax, sugar and similar substances, in addition to meconic and lactic acids.
LACTIC ACID (hydroxypropionic acid), C 3 H 6 0 3.
Two lactic acids are known, differing from each other in the position occupied by the hydroxyl group in the molecule; they are known respectively as a-hydroxypropionic acid (fermentation or inactive lactic acid), CH 3 CH(OH) CO 2 H, ands-hydroxypropionic acid (hydracrylic acid), (q.v.), CH2(OH) CH 2 CO 2 H.
Although on structural grounds there should be only two hydroxypropionic acids, as a matter of fact four lactic acids are known.
Fermentation, or ethylidene lactic acid, was isolated by K.
It may be prepared by the lactic fermentation of starches, sugars, gums, &c., the sugar being dissolved in water and acidified by a small quantity of tartaric acid and then fermented by the addition of sour milk, with a little putrid cheese.
Lactide, O` CH (CH 3) CO >O, a crystalline solid, of melting-point CO CH(CH3) C., is one of the products obtained by the distillation of lactic acid.