The effect of the exogenous folate concentration on the biosynthesis of pteroylpolyglutamates in Lactobacillus casei and the folate polyglutamate distribution in Escherichia coli.

None of the remaining 67 isolates utilized aminoacetone when washed suspensions of the bacteria grown on L-threonine were incubated under standard conditions (Higgins et al., 1968). It was concluded that none of the 83 isolates metabolized L-threonine via aminoacetone. Additional work (S. C. Bell & J. M . Turner, unpublished work) suggests that all the selected isolates possessing high L-threonine 3-dehydrogenase activity catabolize 2-amino-3-oxobutyrate by cleavage to glycine and acetyl-CoA, as shown for a species of Arthrobacter(McGi1vray &Morris, 1969). It seems unlikely that any commonly occurring bacterium degrades L-threonine by a route involving aminoacetone as an obligatory intermediate.