UNIDENTIFIED FACTORS REQUIRED BY LACTOBACILLUS CASEI* IV. EVIDENCE FOR TWO GROWTH FACTORS IN PURIFIED LIVER EXTRACTS BY LOUISE J. DANIEL,t

Scott, Norris, and Heuser (1) and Daniel, Scott, Heuser, and Norris (2) reported that the unknown growth-promoting activity in several natural products for LactobaciUua casei was multiple in nature. The latter investigators proposed the existence of two unknown factors as an explanation for the wide variations in response to different antipernicious anemia liver extracts obtained with L. casei on an amino acid basal medium containing strepogenin concentrate. Peeler, Daniel, Norris, and Heuser (3) found that one portion of the strepogenin activity of strepogenin concentrates prepared from casein for L. CXX& is distinct from that present in purified antipernicious anemia liver preparations and that it is proportional to the glutamine content of these concentrates. Studies’ in this laboratory (4) with chicks fed a soy bean meal diet and with hens fed a purified diet have demonstrated that 95 per cent ethanolsoluble liver paste contains an unidentified factor necessary for chick growth and hatchability. McGinnis and Carver (5) have confirmed this work with chicks. Hill, Scott, Norris, and Heuser (6) reported an unidentified growth factor for chicks fed a soy bean meal diet, in whey, dried distillers’ solubles, and dried brewers’ yeast. Hill (7) has confirmed these findings ‘by reporting a factor in whey that can be demonstrated with chicks fed a soy bean meal diet, but only when the soy bean meal itself is deficient in the factor. He found that whey produced a suboptimum growth response, whereas fish-meal supported maximum growth. The