Escherichia coZi B 166 synthesizes as much vitamin B, when growing on serine or glycine plus glycolaldehyde as does its parent (E. coZi B) on unsupplemented medium. Suspensions of strain B 166 harvested after growth on serine + glycine plus glycolaldehyde, and incubated with glucose and NH,+, only synthesize vitamin B, when glycolaldehyde is added ; serine + glycine increases the synthesis. Strain 22-99 produces more vitamin B, when grown on glycolaldehyde plus serine + glycine than when it is

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... rown on the amino acids alone, while, depending upon the conditions of growth, vitamin B, synthesis by suspensions is absolutely or partially dependent on serine + glycine plus glycolaldehyde. However, serine + glycine plus glycolaldehyde have little effect on the biosynthesis of vitamin B, by wild-type E. coli during growth, or in washed suspensions.