Concurrent decrease of enzymic activities concerned with the synthesis of coenzyme B 12 and of propionic acid in Propionibacteria

Abstract

Cells of Propionibacterium shermanii grown aerobically produce far less of the corrin ring of vitamin B 12 than those cells grown anaerobically. The decreased amount of the corrin ring is in part explained by the diminished activities of enzymes concerned with the synthesis of the porphyrin-like ring of B 12. It has been found that the activity of δ-aminolevulinic acid synthetase in extracts of aerobically grown cells is about 60% of that found in extracts of anaerobically grown cells. Furthermore, the δ-aminolevulinic acid dehydrase activity in aerobic extracts is either not demonstrable, or only about 10% of that in extracts of anaerobically grown cells. The diminished concentration of coenzyme B 12 in aerobically grown cells is reflected in the fatty acid composition of the fermentation products. Propionic acid, the predominant fatty acid among the products of the anaerobic fermentation, occurs in much smaller quantities as a product of aerobic fermentation. This is consistent with the well-known dependence of the methylmalonyl CoA-succinyl CoA isomerase reaction on coenzyme B 12. The addition of coenzyme B 12 to extracts of aerobically grown cells restores the propionate-succinate conversion to only about 30–50% of that found in extracts of anaerobically grown cells. It appears, therefore, that along with the decreased activities of enzymes concerned with B 12 synthesis, there is a concurrent decreased activity of an enzyme system which depends in part on coenzyme B 12. Since the cellular biotin concentration appears to be dependent on the amount of the biotin-dependent enzymes, the finding that extracts of aerobically grown cells contain less biotin than those of cells grown anerobically may be the result of the decreased amount of the functional biotin dependent enzyme.