Saccharomyces Cerevisiæ. Oval or ellipsoidal cells; reproduction by budding; ascospores, rapidly at 30° C., slowly at 12° C., not formed at all at lower temperatures; film formation, seven to ten days at 22° C.; an active alcoholic ferment, producing in a fortnight in beer wort from 4 to 6 per cent. by volume of alcohol (Jörgensen). This species is a typical English "high" yeast, possessing the power of "inverting" cane-sugar previous to producing alcohol and carbonic acid. It is said to have no action on milk-sugar.
| S. Ellipsoideus | S. Pastorianus |
Saccharomyces Ellipsoideus I. Round, oval, or sausage-shaped cells, single or in chains; ascospores in twenty-four hours at 25° C. (not above 30° C., not below 4° C.). Grown on the surface of wort-gelatine, a network is produced by which they can be recognised (in eight to twelve days at 33° C.). At 13–15° C. a characteristic branching mass is produced. It is an alcoholic ferment as active as S. cerevisiæ. S. Ellipsoideus II. Round and oval, rarely elongated, a widely distributed yeast, causing "muddiness" in beer and a bitter taste. It is essentially a "low" yeast.
Saccharomyces Conglomeratus is a round cell, often united in clusters, and occurring in rotting grapes, and at the commencement of fermentation.
Saccharomyces Pastorianus I. Oval or club-shaped cells, occurring in after-fermentation of wine, etc., and producing a bitter taste, unpleasant odour, and turbidity. The spores frequently occur in the air of breweries.
S. Pastor. II. Elongated cells, possessing an invertose ferment. They do not, like S. pastor I., produce disease in beer.
S. Pastor. III. Oval or elongated cells, producing turbidity in beer. Grown on yeast-water gelatine, the colonies show after sixteen days crenated hairy edges.
Saccharomyces Apiculatus. Lemon-shaped cells. They give rise to a feeble alcoholic fermentation, and produce two kinds of spores—round and oval; they appear at the onset of vinous fermentation, but give way later on to S. cerevisiæ.