Studies on degradation of fats by microorganisms III. The metabolism of butyric acid by A. niger

Sorbic Acid as a Fungistatic Agent for Foods.

“…The evidence presented in this report demonstrates that sorbic acid is related to caproic acid in furnishing carbon f o r mold growth as crotonic acid is related to butyric acid (11,12). The ap-unsaturated fatty acids are intermediates in the normal degradation of fatty acids by molds and by t.he mammalian organism.…”

“…For a detailed review of the reaction mechanisms involved, the reader is referred to Sumner and Somers (18). Based upon the studies conducted by Mukherjee (12), it is possible to present an acceptable hypothesis f o r the mechanism by which sorbic acid inhibits mold growth. Mukherjee found that cyanide was a selective inhibitor of the oxidation of butyric acid to ketones by the action of molds.…”

“…This adds further support to the above scheme of fatty acid utilization by molds. I n a recent series of extensive and well-executed studies (10)(11)(12), Mukherjee has added much to our understanding of the enzyme systems in molds responsible for the degradation of fats. Of the molds isolated from samples of butter procured from a local market, Mukherjee identified and selected 4 strains for test purposes, Aspergillus niger, Pe?ziciZlium g l a z m m , Aspergillus fiavorylzea, and Aspergillus fumigatus.…”

“…Cyanide was found (12) to be a selective inhibitor of the oxidation of butyric acid to ketones by the action of molds. This inhibition was characterized by the total inhibition of crotonic acid oxidation.…”

“…I n other words, cyanide had no effect on the dehydrogenase system of the molds but inactivated the enzyme responsible for conversion of crotonic acid t o P-hydroxybutyric acid. Using cyanide inhibition as a means for interrupting the chain of degradation of butyric acid by molds, Mukherjee (12) was actually able to isolate crotonic acid from the test system as the dibromide with positive identification of the derivative as a p-dibromobutyric acid. Further proof that crotonic acid is an intermediate in the oxidation of butyric acid by molds was obtained in the demonstration that increasing the amounts in the system of the subsequent intermediate, P-hydroxybutyric acid, inhibited erotonic acid formation from butyric acid.…”