Growth Inhibitory Effect of Extracts from Milt (Testis) of Different Fishes and of Pure Protamines on Microorganisms

Abstract

A method has been described for the isolation of protamine from the milt (testes) of fish, employing direct extraction of the organ with dilute sulfuric acid, followed by stepwise precipitation with ethanol. The growth inhibitory effect of different protamine preparations on Saccharomyces carlsbergensis have been studied. 0, 7-0,8 µg clupeine sulphate per ml medium gave complete growth inhibition. It has been pointed out that the type (origin) of the protamine should be given in studies on these substances. The growth inhibition of clupein sulphate on some microorganisms employed in vitamin assays have been tried. For L. plantarum and L. leichmannii growth inhibition was observed at about 5 µg per ml medium, for L. casei at 10 µg, for S. fæcalis at about 150 µg, and for Neurospora crassa at about 50 µg per ml medium Aspergillus niger showed growth promotion, probably caused by enzymatic breakdown of the polypeptide and utilization of the free amino acids.