SACCH. PASTORIANUS I. 345 



2. YEASTS NOT YET APPLIED INDUSTRIALLY. 



Saccharomyces Pastorianus or Saccharomyces Pastorianus I. 



Hansen (Figs. 68, 69). 



Bottom-fermentation yeast. 



Sedimentary forms developed in yeast : Predominantly 

 elongated and sausage-shaped, also large and small oval and 

 round cells (Fig. 68). When this species is cultivated in wort 

 near its maximum temperature for growth, its vegetation 

 consists of sausage-shaped and elongated cells. The tempera- 

 ture limits for budding in wort are 34 and 0-5 C. 



It frequently occurs in the air of fermenting rooms, and is 

 also found in diseased beers. It imparts to beer a disagreeable 

 bitter taste and unpleasant odour ; it may also produce 

 turbidity, and interfere with the clarification of beer in the 

 fermenting vessel. 



According to the investigations of Mach and Portele, this 

 species may also be successfully used in wine fermentation. 

 Saccharose, dextrose, Isevulose, and maltose are fermented, 

 but not lactose. 



Ascospore-formation (Fig. 58, 2) : 



At 31-5 C. no ascospores are developed. 



29-5-30-5 the first indications are seen after 30 hours. 



29 ,, ,, 27 ,, 



27-5 24 



23-5 26 



18 ,, ,, 35 ,, 



15 50 



10 ,, 89 ,, 



8-5 5 days. 



7 7 



5> J> 



3-4 14 



0-5 no ascospores are developed. 



Size of spores 1-5 to 5 p. 



