The following report was published under the title 'Schizosaccharomyces liquefaciens n. sp., eine gegen freie schweflige Säure widerstandsfähige Gärhefe' by A. Osterwalder in the journal Mitteilungen aus dem Gebiete der Lebenmitteluntersuchung und Hygiene (Volume 15, pages 5-28) in 1924.
This NIH library translation (NIH-96-117) from German into English was provided by Ted Crump, translator. Copyright restrictions apply. This translation is for exclusive use of Frans Hochstenbach, and has been edited by Frans Hochstenbach and Norman Hu.
Early November 1921, our experimental station received from a wine dealer in western Switzerland an exceedingly over-sulfurized grape juice, namely a 1921 Picpoul francais from Montpellier, with 72o Oechsle must weight, which the company did not wish to bring to fermentation despite various treatments. The total sulfuric acid content, measured by the Schmitt-Ripper method (Schweizerisches Lebensmittelbuch. 3rd ed., 1917: p. 281) immediately upon receiving the juice, was 546.5 mg/L, which reflected the addition of at least 103 g metasulfite per hectoliter, since the juice had been treated with potassium metasulfite in Montpellier. The 144.6 mg/L free sulfuric acid still present was sufficient to suppress fermentation in the juice. We blended this over-sulfurized Picpoul with a sterile grape juice previously brought to fermentation with pure yeast, at ratios of 20:20, 50:20 (50 ml Picpoul plus 20 ml fermenting juice) and 100:20, i.e., 100 ml Picpoul plus 20 ml freshly fermenting juice. In just two days, the 20:20 mixture was fermenting, while after four days the two other mixtures of 50:20 and 100:20 were also fermenting. Upon microscopic examination of the cloudiness of this fermenting mixture, in addition [to observing] the elliptical pure yeast that we had added, we were struck by numerous elongated cylindrical cells, not infrequently with internal partitions, which were reminiscent of Schizosaccharomyces.
. . . . . . . . . .
Schizosaccharomyces liquefaciens Osterw. obtained from an over-sulfurized French red grape juice, formed roller-, club- and hand grenade-shaped cells or roller-shaped cells thickened in the middle. Shorter roller-shaped yeast were 7.9 micrometer long and 3.9 micrometer wide, numerous medium-length yeast were ca. 16 micrometer long and up to 3.2 micrometer wide, in addition to long cells of up to 32 micrometer. Often, two cells formed by cleavage of the mother cell were still bound to each other over a short length at an up to 90 degree angle. Many yeasts were divided by a partition into two cells. In smear cultures, 15% gelatin liquefied with 10% grape juice within 14 days. Spores formed abundantly on the gelatin, while only sparsely on gypsum blocks. The spores were spherical or elliptical, with a diameter of 2.6 to 3.5 micrometer, and stained a blue-violet with potassium iodide. Up to 6 percent alcohol (by weight) was formed in Theiler's pear or grape juice after approximately 70 days at room temperature. The optimum temperature for fermentation activity was ca. 34 degree [Celsius]. Levulose, dextrose, galactose, sucrose, maltose, raffinose, D-mannose, alpha-methylglucoside are fermented, but not lactose, melibiose, and dextrin. Malic acid is decomposed without forming lactic acid, but tartaric, acetic, lactic, succinic, and citric acid are not. It resists large quantities of free sulfuric acid, for instance 555 mg/L, and in one case even 674 mg/L.
On the basis of the following key, it will be possible to determine the different Schizosaccharomyces species, including Schizosaccharomyces liquefaciens.
,-ferments galactose, readily liquefies the gelatin,
| forms many spores on the nutrient gelatin,
| resists large quantities of SO2:
| Schizosaccharomyces liquefaciens Osterw.
,-forms spores|
| | ,-decomposes malic acid:
,ferments sucrose| | | Schizosaccharomyces mellacei Jorgensen
| | | |
| | `-does not |
| | ferment |
| | galactose|
| | `-does not decompose malic acid:
| | Schizosaccharomyces pombe P. Lindner
| |
| `-forms no spores: Schizosaccharomyces asporus Eykman
|
`Does not ferment sucrose, as a rule forms 8 spores, but sometimes 4:
Schizosaccharomyces octosporus Beyerinck
In conclusion, this question must be posed again: Can a yeast that is so resistant to free sulfuric acid, such as Schizosaccharomyces liquefaciens, have any practical importance. It would hardly be noticed in fermenting fruit and grape juice; the more strongly-fermenting yeast species and strains develop more rapidly, especially since they also overcome more readily lower temperatures which very often prevail in the wine cellar than Schizosaccharomyces liquefaciens, which only ferments rapidly at higher temperatures, that is, 28 to 34 degree [Celsius]. However, it could certainly be useful in situations where the usual fermentation yeasts are killed off or inhibited in their growth by sulfuric acid for long periods; namely, in over-sulfurized fruit and grape juices, which are formed once in a while ever since potassium sulfite is used in the production of wine. [The usage of potassium sulfite] has enjoyed greater popularity, but occasionally, whether due to unfamiliarity or convenience, doses are not weighed, and it is added to the juice in excess.
To bring 'stable' [no longer fermenting after addition of excess sulfite] juices into fermentation is a somewhat laborious process if one does not wish to wait until all free sulfuric acid has disappeared. This is [a laborious process], because, after gradation, a small amount of foreign fermenting juice is mixed with a small part of the stable juice, and then another stable amount is added during strong fermentation; and this experiment is repeated until everything has been brought into fermentation. The process is not simplified much using a yeast accustomed to sulfuric acid, the so-called sulfite yeasts, which clearly cannot cope with large amounts of free sulfuric acid that often occur in stable juices, and are likewise killed off from direct exposure [to sulfite]. On the other hand, the gradation technique can be followed if the yeast Schizosaccharomyces liquefaciens is used, whereby a higher fermentation temperature, which may be used without any question with stable juices, and the use of abundance of pitching yeast, very much favor an early fermentation. With the first signs of alcoholic fermentation, however, one must not fail to add a strong, proven wine yeast strain to the juice, which now is no longer in danger of being poisoned, since the free sulfuric acid has been bound by the fermentation aldehyde.
Schizosaccharomyces liquefaciens is available from the Central Facility for Fungus Cultures [Centraalbureau voor Schimmelcultures] in Baarn, the Netherlands.