8 EXPEEIMENT STATION BECOED. 



for which the name ' mycophenolic acid ' and the formula CttHmOo are suggested. 

 This substance behaves like a weak dibasic acid and, like penicillic acid, re- 

 sembles the lichen acids in many ways. Among the other metabolic products 

 of the organism, alcohol, oxalic acid, and mannitol were found. 



" In the present gaper it has been shown that species of Penicilllum, so closely 

 related that until recently they were not distinguished by morphologists, differ 

 quite markedly in their metabolism. It is greatly to be desired that the whole 

 genus be studied biochemically. The chemical findings will no doubt supple- 

 ment the morphological in many important ways. Indeed, as indicated by the 

 constant presence of alcohol and the formation of penicillic acid by P. puberulum 

 and the formation of mycophenolic acid by P. stoloniferum, it is not impossible 

 that characteristic chemical properties may help to distinguish between species 

 or strains not now sharply separated by morphologists." 



The influence of certain acid-destroying' yeasts upon lactic bacteria, Zae 

 NoETHKUP (Michigan Sta. Tech. Bui. 15, pp. 3-35, figs. 5). — A chromogenic (red) 

 yeast in addition to a yellow coccus was isolated from what was supposedly a 

 pure culture of lactic acid bacteria. In order to preserve the strain of red 

 yeast, transfers were made from milk to milk whereby it was noted that the 

 milk first curded before the characteristic pigmentation appeared. When lactic 

 acid bacteria were cultivated together in the same media with this yeast, the 

 bacteria seemed to retain their vitality over a much greater period than when 

 they were cultivated alone. This was proved to be due to the acid-consuming 

 or acid-reducing power of the yeast. The yellow coccus, while capable of pro- 

 ducing acid, was a negligible factor so far as the preservation of the lactic acid 

 bacteria was concerned. 



In order to determine absolutely that the yeast was an add reducer, it was 

 compared with a scum yeast from brine pickles, a butter yeast, and a yeast 

 isolated from whey. In this respect the pickle brine yeast was found to be 

 the greatest consumer of acid and the red yeast the weakest one. The acid 

 reduction in the case of the red yeast was considered of secondary importance. 

 When grown together with either the Bacterium hulgaricum, another high acid- 

 producing strain, or 2 organisms which were low producers of lactic acid, it 

 was noted that no growth was obtained in the case of the strong, acid-producing 

 bacteria but, on the other hand, the 2 lactic acid bacteria used were not alive, 

 this being due to the long sojourn in their own products. 



In some comparative tests of acid reduction made with mrred cultures of 4 

 yeasts and 4 lactic acid bacteria in milk and whey, some of which were strong 

 acid producers and others weak, it was noted that it was quite possible to in- 

 crease the acid-producing qualities of the weak acid strains by growing them in 

 the same medium with a yeast having the characteristics of the red yeast. 



The rejuvenating property of the yeasts, while due in part to the acid-produc- 

 ing function, in the case of red yeast is also partially due to rennet and pepsin- 

 like enzyms produced by the yeast. One of these enzyms at least is extra- 

 cellular in old cultures; the rennet-like enzym and probably the pepsin-like 

 enzym were separated from yeast by filtration. Although it was difficult 

 to determine the presence of the pepsin-like enzym in the filtrate by means of 

 its visible action on the milk, the stimulating action of the filtrate is directly 

 comparable with that of the pure pepsin solution. The pepsin-like enzym is 

 the one which stimulates the curding function of the lactic bacteria, although 

 at first it was suspected that the lactic organisms in some way caused tie 

 rennin in the filtrate to act more quickly. 



" The question was raised as to whether the enzyms acted upon the milk con- 

 stituents and thus indirectly upon the lactic bacteria, or whether the influence 

 was immediately upon the lactic bacteria. It was ascertained that the rennet 



