The effect of branched‐chain alphaketo acids on the utilization of other branched‐chain compounds by lactobacillus casei

Abstract

The effects of branched-chain keto acids on a mutant of L. casei (280-16A) requiring D-alpha-hydroxy acids for optimum growth have been studied. KICA, while showing little effect on the utilization of lactic acid by the bacteria, competitively inhibits the uptake of alpha-hydroxyisocaproic acid and alpha-hydroxyisovaleric acid by this organism. KICA also inhibits several intracellular reactions, including the conversion of D-lactic acid and D-HICA to an as yet unidentified growth-essential metabolite. Thus, it may be argued that alterations in the normal chemical environment of the brain produce inhibition of a multitude of enzymatic reactions. Some of these may be concerned with intermediary metabolism and are potentially reversible upon dietary correction of the environmental abnormality. On the other hand, deviation from the usual ratio of metabolites offered to the brain during the early phases of its growth and myelination may produce a permanent abnormality in its chemical structure.