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i.f.RUSERSTAND AA Fig. 123.- Monilia candida (Bonorden), Hansen. Mould growth from an old
culture. a, Chains of more or less thread-shaped cells ; at each node a whorl of oval-shaped yeast cells often occurs. b, The same form, but without oval yeast cells. (, Typical mycelium with septa. d, Oidium-like cells. e, Pearshaped cells. f, Lemon-shaped cells. 1909. (After Hansen.)
4:9 vol. per cent. The cells were then still alive. The fermentation proceeded very slowly in these cases. The fungus withstands high temperatures, e.g., it ferments vigorously at 40° C. In wort, the temperature limits are 42° to 43° C. and 6° to 4° C.
It is a remarkable circumstance that in the fermentation of the saccharose solution neither invertase nor invert sugar could be detected. Consequently the vigorous fermentation generated in the saccharose solution by Monilia candida must be quite unique, because saccharose was only known to be fermented after previous inversion. The invertase not being detectable by existing chemical methods, it follows that the fermentation must be regarded as a direct one. Nevertheless, Hansen indicated the possibility that the inversion takes place inside the cells and that the invert sugar produced is fermented as soon as it is formed. E. Fischer and P. Lindner by grinding the cells have recently discovered an invertase insoluble in water, i.e., a ferment which is closely connected with the plasma of the cell. At the same time they found that this species contains maltase. According to Bau the fungus can ferment diastase dextrin.
Monilia javanica, Went and Prinsen Geerligs, occurs in “ Raggi," which is applied in the manufacture of arrack in Java (see p. 260). On solutions containing sugar this species forms a film, which, however (and this distinguishes it from the previous species), disappears as soon as fermentation begins. It further differs from M. candida in that it inverts saccharose in the usual way, and the latter is then fermented; it also ferments dextrose, levulose, maltose and raffinose. When 5 per cent. of alcohol has been formed, growth and fermentation cease. The alcohol it produces has an unpleasant smell and taste.
A Monilia species has been described by Forti which has a detrimental influence on the yeast in wine.
Chalara mycoderma, Cienkowski. Like Monilia, this fungus (Figs. 124 and 125) forms a film on liquids ; it is composed of a branched mycelium which abstricts here and there globular or oval, but seldom
pear-shaped conidia, 4 to 11 M, most generally 4 to 6 u in greatest diameter. They are formed by abstriction, in part
Fig. 124.-Chalara mycoderma, Cienkowski. Connected mycelium with conidia.
49. The figure to the left shows separated mycelium branches and conidia. 799. (After Cienkowski.)
from sterigmata and partly from the surface of the limb. This species thrives on wort and lager beer. It is found in the free state on grapes and on cow dung.
Oidium lactis, Fresenius. Oidium lactis, Fresenius (Figs. 126, 127 and 128), develops colourless, branched hyphæ, which form a white felt. The conidia develop by a division of the threads, and have, as a rule, a rectangular longitudinal section, but other forms are also to be observed; their length is most generally 10 to 30 y, and breadth 3 to 5 p. The temperature limits for the growth in wort are near 37° C. and below to C.; for the film formation 36ło to 371° C. and about 3° C.
An inter-growth similar to that observed by P. Lindner in Botrytis cinerea was found by the author and Schjönning in Oidium lactis (Fig. 128). When, for example, a young,
FIG. 125.-Chalara mycoderma, Cienkowski. Mycelium members, abstricting
conidia. 1180. (After Hansen.)
vigorous mycelium is seeded in a thin layer of water, a more vigorous cell here and there grows into its feebler neighbouring cell and there forms conidia chains.
This fungus is found in general on milk which has been standing. According to Hansen's investigations it generates a trace of alcohol in wort and dextrose yeast water. According to Lang and Freudenreich it can generate 1 vol. per cent. of alcohol in milk-sugar and dextrose solutions.
In breweries it is to be found on malt, lager vessels,
casks, piping, etc. It is also found occasionally on pressed yeast. Jörgensen states that he has found it in
Fig. 126.-Oidium lactis, Fresenius. A, A branched mycelium thread mom,
distributed horizontally in the liquid medium ; projecting obliquely into the air at the line Lor, a branch divided by septa into a chain of cylindrical conidia, p. B, Conidia chain at the commencement of the separation of its members from each other. About 18. (After De Bary.)
large amount on top yeast when this is allowed to remain at rest after fermentation has ceased.