An enzyme which liberates Pi from myo-inositol hexaphosphate (phytic acid) was shown to be present in culture filtrates of Bacillus subtilis. It was purified until it was homogeneous by ultracentrifugation, but it still showed two isozymes on polyacrylamide gel electrophoresis. The enzyme differed from other previously known phytases in its metal requirement and in its specificity for phytate. It had a specific requirement for Ca2' for its activity. The enzyme hydrolyzed only phytate and had no action on other phosphate esters tested. This B. subtilis phytase is the only known phytate-specific phosphatase. The products of hydrolysis of phytate by this enzyme were Pi and myo-inositol monophosphate. The enzyme showed optimum activity at pH 7.5. It was inhibited by Ba2+, Sr2+, Hg2+, Cd2 , and borate. Its activity was unaffected by urea, diisopropylfluorophosphate, arsenate, fluoride, mercaptoethanol, trypsin, papain, and elastase.

A sclerotia-forming actinomycete of the genus Chainia secreted high levels of glucose (xylose) isomerase when grown in submerged culture on a wheat bran -yeast extract medium.Maximum activity (4 units/ml) was obtained after 3-4 days when the cell bound activity was 0.19 units/ml.The two enzymes differed significantly in pH optima (extracellular, 9.5; cell-bound, 7.0) and in their adsorption behaviour on CM and DEAE celluloses.Both Mg ++ and Co ++ are re,tired by the cell-bound enzyme for its optimum activity while either Mg ++ or Co ++ is necessary for the extracellular enzyme.

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