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Fleischmann[63] gives a formula for preparing an artificial koumiss from
separated cows' milk, water, cane sugar, and milk sugar, with the
addition of distillery yeast. Needless to say, this product must possess
some of the characteristic by-flavour of the yeast employed, and is less
suitable than koumiss prepared by the aid of a lactic yeast. Schipin
investigated the fermentation of koumiss and found three distinct
organisms.

Rubinsky in a recent article threw much light on the phenomena of
koumiss fermentation. According to him, koumiss contains almost
invariably four different organisms, viz., koumiss yeast, koumiss
bacterium (_Lactobacillus_), _Streptococcus lactis_ (Lister), _Bacterium
aerogenes_, and occasionally _Bact. caucasicum_ (Nikolajewa). For the
preparation of normal koumiss only the two former organisms are
required; they exceed in number any of the other organisms whose
presence in the dairy is unavoidable. The presence of the two latter
organisms is favourable to the production of good koumiss, as, by
inducing a preliminary lactic fermentation, they tend to inhibit the
growth of undesirable extraneous bacteria, etc. In medium and strong
koumiss they die out on account of the amount of lactic acid formed
(1%).

Koumiss yeast possesses strongly differentiated protoplasm, but lacks
any cultural characteristics. Abundant growth occurs in milk, and lactic
acid (0.3%), alcohol, carbon dioxide, albumens and peptones, volatile
acids, and aromatic substances are formed.

Koumiss bacterium is related to the _Lactobacillus_ of various other
fermented milks, and is similar to _Bac. acidophilus_, and possesses
like these a distinct polymorphism (branched cells, long and short
bacilli, etc.). It is non-sporogenous, has an optimum temperature of 90
deg. to 97 deg. F., and possesses cultural characteristics similar to
those of the rest of the _Lactobacilli_.

The by-products of koumiss yeast appear to favour the growth of the
koumiss bacterium, as this organism, like the other _Lactobacilli_, is
favourably influenced by the presence of small quantities of peptone,
alcohol, and acid.

The organisms found by Schipin consisted of a species of _Saccharomyces_
and two bacilli, _Bacillus acidi lactici_ and a non-sporulating
bacillus. The latter organisms coagulate milk at 98 deg. F., but not at
room temperature, and alth