Cellulases from Sporocytophaga myxococcoides

Two extracellular cellulases active on carboxymethylcellulose have been isolated from the culture supernatant of Sporocytophaga myxococcoides by a series of gel‐filtration and ion‐exchange chromatography steps. Cellulase II, being present in highest amount, had a molecular weight determined by gel electrophoresis of 52000, p l was 4.75 and a relatively broad pH optimum (5.5–7.5). Cellulase I had a molecular weight of 46000. p l was 7.5 and the pH optimum 6.5–7.5. Both cellulases had a very low carbohydrate content, possibly present as impurities. They had fairly similar amino acid compositions. The specific activity of cellulase I was about 6 times higher than that of cellulase II. Both cellulases acted as endoglucanases. A cell‐associated cellulase, present in amounts corresponding to about 10% of total activity, was partly purified. It showed similarities with cellulase II.