Studies on the relationship between the Lactobacillus bulgaricus factor and pantothenic acid.

Since the initial report on the existence of a factor (LBF) that is essential for the growth of Lactobacillus bulgaricus, Sarles strain (Williams, Hoff-J0rgensen, and Snell, 1949), several reports on its nature and role in nutrition have appeared. Rasmussen et al. (1950), employing paper chromatography and the bioautographic technique of Winsten and Eigen (1948), found that yeast extract contains five substances that promote the growth of L. bulgaricus. More detailed studies with this technique (Long and Williams, 1951) indicate that as many as seven interchangeable forms of LBF occur in culture filtrates of Bacillus megatherium. These forms were named LBF-1, LBF-2, etc., to LBF-7, the most rapidly moving form in an ascending butanol-water paper chromatographic system. This naming system will be used for convenience in this report. A preliminary report (McRorie, Masley, and Williams, 1950) showed that the requirement of L. bulgaricus for LBF can be replaced by high levels of pantothenate and that about 30 m&g of pantothenate, expressed as the calcium salt, are bound in each unit of LBF. Another report (Brown, Craig, and Snell, 1950) described similar findings and reported that LBF activity is formed when coenzyme A is degraded enzymatically. Mims (personal communication from Dr. 0. D. Bird) early in 1950 also observed the interchangeability of LBF and high amounts of pantothenate for growth of the LBF test organism. The interchangeability of pantothenate and LBF was further demonstrated for the rat (McRorie, Sherwood, and Williams, 1950). On a pantothenate-free purified diet rats were able to utilize LBF for growth. Gains on LBF equaled gains obtained on equivalent amounts of pantothenate. Snell et al. (1950) have described the synthesis and chemical nature of one form of LBF. The synthetic product is N-pantothenyl-,-mercaptoethylamine. The disulfide form of this compound was named pantethine. This appears to be identical with LBF-7. Although a close relationship is likely between the synthetic compound and a portion of coenzyme A, LBF-7 or, presumably, pantethine does not occur in enzymatic hydrolyzates of coenzyme A (Long and Wil-