CONTRIBUCION AL CONOCIMIENTO DE LAS LEVADURAS DEL AGUAMIEL Y DEL PULQUE IV

Resumen

The description of a new species of yeast, forming no spores, is given in this paper.
We place it in the genus Torulopsis and consider it a new species because of its characters, under the name aquamellis, because it was found in the "aguamiel", liquid produced by the "maguey" (Agave) used in Mexico for the elaboration of the fermented alcoholic beverage called "pulque".
The fundamental characters of this new species are the following:
1. Culture in beer-worth: At 24°-25° C., little sediment appears after 48 hours; alter 9 days a ring is formed and in 20 days isolated spots of veil appear, which after 30 days cover the whole surface of the culture; in 45 to 60 days a mucous veil is formed. After 48 hours at the above mentioned temperature some cells are round (6-7) micra in diameter and others ovoid (6-7 by 7-8) micra. In some, vacuoles are to be seen and in all of them numerous very small fat droplets.
2. Culture in wort-agar: At 24°-25° C., after 10 days circular colonies are obtained, with smooth surface and some radial very thin grooves; elevation convex or pulvinate; borders entire and dark brown in colour with a reniform shiny aspect. After 60 the surface becomes very rugose, borders undulated, the shine is lost and the brown colour darker.
3. Streak culture: In wort-ager, after 30 days at 25° C., the form is extended, surface rugose at the middle and even near the borders which are undulated; convex elevation; not translucid, dark brown and uniformly shiny.
4. Giant colony: In wort-gelatin after 30 days a t 18°-19° C., appears with circular form, even surface, umbonate elevation, entire borders, not translucid, very shiny and yellowish-brown in colour.
5. Limit and optimum temperatures for development are:
Mínimum temp.: 0°-2° C.
Optimum temp.: 24°-26° C.
Maximum temp. : 33°-35° C.
6. Liquefaction of gelatin: Begins between 15 and 30 days and is greater after 45 to 60 days.
7. Fermentation: Does not ferment any sugars.
8. Assimilation of sugars:
Dextrosa         +          Levulose     +
Manose           +          Galactosa    -
Saccharose     +          Maltosa       +
Lactosa            -           Raffinose    -
9. Assimilation of Nitrogen:
Potassium nitrate          +     Peptona         +
Amonium sulphate       +     Asparagine    +
                          Urea        +
10. Ethyl alcohol as substratum for development; very little after 10 days; moderate after 30.