Flavin-linked oxidative enzymes of Lactobacillus casei.

A previous communication (2) indicated that heme-linked enzymes were not involved in the very considerable capacities of various representative microaerophilic lactobacilli for electron transport from a variety of oxidizable substrates to oxygen, but that specific flavin components were present in high concentration in each of these organisms. To determine the possible central role of flavin enzymes in electron transport to oxygen in these organisms, the catalytic systems capable of oxidizing various substrates have been studied with soluble enzyme preparations obtained from cells disrupted by sonic oscillation. The present paper describes such studies with a strain of LactobaciZZu.s casei, and comparable studies with certain oxidative systems were pursued with other lactobacilli as well. The results suggest that electron transport to oxygen in these lactobacilli is largely, if not exclusively, mediated by a series of substrate-specific, flavin adenine dinucleotide-requiring enzyme systems.