SOME CHARACTERISTICS OF PROTEINASES OF AN OBLIGATELY PSYCHROPHILIC RED-PIGMENTED BACTERIUM AND OF SERRATIA MARCESCENS

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Abstract
Supernatants of cultures of a red-pigmented psychrophilic bacterium and of a strain of Serratia marcescens contained proteolytic enzymes that hydrolyzed casein,/3-IactogIobuIin and haemoglobin. With casein as the substrate, optimum activity of the enzyme system of the psychrophile was at pH 10 and at 40-45 °C; optimum activity of the 5. marcescens enzyme system was at pH 9.0 and 45° C. Calcium stimulated activity and protected proteinases of both organisms against heat inactivation. Proteinases of both organisms possess high temperature characteristics and relatively high temperature optima. The results indicated that the proteinase system of the red psychrophile differs from those of some other cold-tolerant bacteria {Cytophaga and Pseudomonas) and that it is similar to but not identical with the proteinase system of Serratia marcescens.