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water is rendered ropy and viscous by I., while II. only causes turbidity and carbonic acid evolution. A higher amount of sugar is prejudicial to the development of these bacteria, for which reason, therefore, lightly fermented beer is comparatively seldom ropy. The optimum temperature for their development is 33° C. The bacteria are frequently

found in water analyses.

Bacillus viscosus III., L. Vandam, forms rods which are 20 μ long and 0.7 μ broad; they usually occur isolated; sometimes they are joined in chains of two or three members. This species was found in English beer; the ropiness is conditioned by the presence of sugar; air is necessary for the development of the species.

Bacillus viscosus vini, Kramer, makes white wine viscous in the absence of air. It forms rods 2 to 6 μ long and 06 to 08 μ broad: these are often joined in manymembered chains.

Lactic Acid-forming Species.

Mention has been already made of the discovery of lactic acid bacteria by Pasteur, of their importance in distilleries, and of their recent introduction into the latter in the form of pure cultures.

The first to isolate a pure lactic acid bacterium for the above purpose was, as has been said, F. Lafar. The species isolated and applied by him was Bacillus acidificans longissimus, Lafar, the cells of which are 25 to 25 μ long and about 1 broad.

μ

Bacillus acidi lactici, Hueppe, consists of immotile rods which are 10 to 17 μ long and 03 to 04 μ broad; they are frequently connected in pairs, rarely in four-membered chains.

This bacillus is aerobic and does not liquefy gelatine. It loses its souring power if it is cultivated for a long time on

a sugar-free nutrient medium. As a result of seeding this species in wine, Kramer produced "Zickenwerden" (lactic acid sharpness).

Saccharobacillus Pastorianus, van Laer, is responsible for that disease known as the "turning" of beer. Pasteur made the discovery that the disease is caused by bacteria. The species thrives best on malt extract-agar with a little alcohol added; this medium should be used when it is desired to obtain a pure culture. It develops in beer only when the latter contains a small amount of hop extract. According to van Laer it readily ferments saccharose (without inversion), maltose and dextrose, but lactose only with difficulty. Lactic acid, ethyl alcohol and small amounts of acetic and formic acid are found in the fermentation.

Its

FIG. 146.-Lactic Acid Bacteria.

development in beer is prevented by over 7 per cent. of alcohol.

Butyric Acid-forming Species.

It has been stated that Pasteur discovered a butyric acid bacterium which he named Vibrion butyrique; later it was shown that this fermentation is caused by many species, which have already been alluded to as the cause of much harm in breweries.

Clostridium butyricum, Prazmowski (Bacillus amylobacter, van Tieghem), probably includes several species. The form described by Prazmowski (Figs. 134 and 137) consists of rods 1 μ broad, of which the young individuals contain a substance granulose which, however, is only formed if the

bacteria live in an entirely anaerobic state, and which, like starch (amylum), is stained blue by iodine. (From this the generic names Amylobacter and Granulobacter, sometimes used, are derived.) They are provided with flagella (Fig. 134), and display active motion. When the spores develop, the rods swell out at one end and become club-shaped (Clostridium form) (Fig. 137). According to Prazmowski, the spores survive the temperature of boiling water for five minutes; after ten minutes only a few of the strongest are alive, whilst all die in fifteen minutes. The species is

strongly anaerobic.

Bacillus butyricus, Hueppe, differs from the above. species in being aërobic.

Granulobacter saccharobutyricum, Beijerinck, is of general occurrence on barley corns, and therefore also on green malt, groats, flour, etc. It is one of the most injurious species in distilleries. It decomposes dextrose as well as maltose, and produces butyric acid, butyl alcohol, carbonic acid and hydrogen; gelatine is not liquefied by this species.

The cells

Bacillus lupuliperda, Behrens, is classified here inasmuch as it orms butyric acid when it is cultivated in a nutrient liquid containing sugar. Behrens found it in hops which had become warm. are motile; they are 07 μ to 2.5 μ long and 0.7 μ broad. It liquefies gelatine, and can be cultivated in an extract of hops. This bacillus is partly the cause of the spontaneous heating of hops, and forms trimethylamine and ammonia.

Finally, two bacilli have yet to be mentioned which cannot be classified in the above groups. One is

Bacillus piluliformans, Müller-Thurgau.-The rods are 3 μ to 10.5 μ long, most frequently 4 μ to 6 μ, and are 0·75 μ broad. It causes in wine a remarkable disease described by Müller-Thurgau. In a red wine it had formed rounded corn-like grains, which clung to the sides of the bottle, but mostly to the bottom; these were in greater part detached by gently moving the bottle. The grains, of which as many as a hundred were found in a bottle, varied very much in size, some being hardly discernible, whilst others had a diameter of as much as 4.5 mm. The wine was of a darker colour than usual; its flavour and smell were but slightly altered; it was clear, but not of good quality.

Bacillus subtilis, Ehrenberg. Hay bacillus.-It is found frequently

on hay.

The spores are very resistant towards high temperatures; according to Brefeld, they survive heating to 100° C. for three hours, to 105° C. for a quarter of an hour, and to 110° C. for five minutes. This species can therefore be obtained by pouring water over hay and boiling the liquor drawn off. The rods are strongly motile, and are furnished with several flagella. It first inverts cane sugar, and then oxidises it to the last trace. During its action on dextrose a strongly reducing lævo-rotatory body is formed (A. J. Brown).

This species is frequently met with in physiological fermentation work. It develops easily in unhopped wort; it does not thrive in acid liquids, and is on that account without significance in the brewery. According to Esaulow, it occurs in kefir; it here participates in the formation of kefir grains, the film it forms on the milk serving as a collecting place for the lactic acid bacteria and yeast.

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