Several periphytic marine bacterial cultures were examined for their content of hydrolytic enzymes. Quantitative assays were done for extracellular and intracellular proteinase, phosphatase, esterase, β-glucosidase, and four polysaccharide hydrolase activities. While some of the enzymes were released extracellularly by growing cells, the greatest amounts of proteinase, esterase, phosphatase, and β-glucosidase were located in the cells and released by mechanical breakage or by cell autolysis. Substantial amounts of proteinase were found in washed cell envelopes of the bacteria. All of the bacteria showed some enzymatic activity against one or more of the algal and microbial acid polysaccharides tested. Enzymes active against these polyanions were found either extracellularly or in cell extracts, depending on the culture concerned. Partial lysis of cell envelopes from two of the periphytes was produced by extracellular or intracellular enzyme mixtures. The ecological importance of bacterial hydrolases and the possible relationship of periphytic bacteria to grazing and detritus feeding invertebrates is discussed.
