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saccharomycetes; this is, however, not the case with Hansen's Torula. By Torula Hansen understands yeast cells which are similar to Saccharomyces, but do not form endospores por develop typical mould growths. As regards the production of alcohol they may exhibit this in all degrees. According to the view held by the same investigator they will some time in the future probably be ranked with forms in th system widely separated from one another. As, however, we are ignorant on this point as yet, these organisms are for the time placed together in a group by themselves.
After Hansen had made clear the conditions for the formation of asporogenous varieties in the saccharomycetes, and since such asporogenous varieties can be formed in nature, it is comprehensible that several forms which appear under the name Torula possibly originate in saccharomycetes. There are Torula species which have all the physiological characteristics common to the saccharomycetes; this is true also as regards the morphological features, but of course with the exception of the property of greatest importance to the saccharomycetes, viz., that of endospore formation.
Torula species are very widely distributed in nature. Hansen found them always present in the ground and in large quantity after winter in the hairy coats of bees and wasps as well as in their nests. The author also found them constantly when investigating a large numberof these insects. Some of these fungi cause a disagreeable taste and smell in wort and, according to Wortmann, also in wines. The latter author found forms, in old bottled wines, which make must slimy. Rich. Meissner has in recent years isolated several species which cause wine to become viscous (see below).
Hansen has thoroughly investigated, among others, seven different species, which have, however, received no systematic name. These are as follows :
Torula No. 1 (Fig. 112).—The cells are 1:5 to 4:5 u in
3. After long standing in wort, this fungus forms a rcely appreciable amount of alcohol without any trace frothing; it does not secrete any invertase.
Torula No. 2 (Fig. 113).—The cells are 3 to 8 in ameter. The protoplasm becomes granular in wort. therwise this Torula behaves essentially like No. 1.
Torula No. 3 is similar to No. 2. In wort it yields vol. per cent. of alcohol with a small but distinct production f froth, and does not form invertase.
Torula No. 4 (Fig. 114).— The cells are 2 to 6 u in
diameter. It inverts saccharose and, in wort, forms a little more than 1 vol. per cent. of alcohol with vigorous frothing.
Torula No. 5.- This species soon forms a grey film over the whole surface of wort, yeast-water and lager beer; the film is only slight on a saccharose solution. The latter sugar is inverted by it; but in wort it produces no noteworthy fermentation and correspondingly only a trace of alcohol.
Torula No. 6 (Fig. 115) exhibits a distinct fermentation in wort and generates in it 1:3 vol. per cent. of alcohol. No fermentation takes place in a maltose solution. It inverts
saccharose and in fifteen days at 25° C. generates 8.8 vol. per cent of alcohol in a 15 per cent. dextrose solution.
Torula No. 7 (Figs. 116 and 117) was found in the soil under vines. It produces 1 vol. per cent. of alcohol in beer wort; on the contrary it excites no fermentation in solutions of saccharose, which it is unable to invert. In yeast water
containing 15 per cent. of dextrose it formed 5:3 vol. per cent, of alcohol.
The last named species are perhaps active in wine manufacture, but hardly so in breweries and distilleries.
Rich. Meissner isolated eleven Torula species which all cause that disease called the ropiness (“ Zähewerden ") of wines; he has shown by experiments that must as well as wine becomes slimy, oily and thick
Fig. 116.–Torula No. 7. Sedimentary yeast.
1909. (After Hansen.)
when seeded with these. Most of these forms do not produce films, but only a yeast ring; must is decolourised by all of them. In the few species which form a film the latter was in some cases white, and in a single instance olive green. Only two of the eleven species referred to bring about alcoholic fermentation. Common to all is the need of oxygen, without which they cannot grow. If the nutrient liquid contains more than 5 vol. per cent. of alcohol, growth as a rule ceases, but at the same time the organisms are not killed. These slime yeasts check the ferFig. 118. ---Saccharomyces apiculatus, Reess. (a) A cell which has begun to develop
mentation, not of the strong yeasts, but only of feebly fermenting yeasts in the first few days of fermentation. The ropiness of wine occurs chiefly in those wines which are poor in tannin ; the disease can therefore
Fig. 117.-Torula No. 7. Film growth on a wort culture ten months old. 1499.
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a bud; a' and a' the same cell after the lapse of 11 and 31 hours; b another budding cell, W after two hours, b" after three hours ; d' is -hour older than c; d was observed at 2 P.M., d' at 31, d" at 37; e 103 o'clock, de 12, e" 123, e" 1; f 21, $ 31, F" 4, f'" 5, f'" 5 o'clock. About 250.
(After Hansen.) be prevented by the addition of tannin, which latter checks the growth of the slime yeasts. The addition of a pure wine yeast is an especially favourable means for suppressing the slime yeasts so completely that the disease does not appear.
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s with I. I peci to our stor eva:1.". Draadi tee meal.i piz 5-211- Buses op 11-13) iacter 5 canal with them.
Saccharomyces Apiculatus, Reess. A bubling fungs which does not form epulosport which iterally occurs in vineyants and orchants 5t risen this name by Rees It has been thoroughly to by Hansen and we owe the following to his investigation
The cells (Figs. 118 and 119), which are generally 6 to 8 m long and 2 to 3 u wide, are in some cases pointed at both onds like lemons, in others oval. The fungus forms both kinds of buds. In order to change into lemon-shaped colls the oval buds must grow through one or more buddings Tho lemon form is produced more especially at the beginning of the budding and has then the preponderance; later the oval colls predominate.