In order to produce cellulosic single cell protein from the cellulose, 163 strains of cellulose assimilating bacteria were isolated from 95 sources and one of them was screened by its strong cellulose assimilating activity; and was identified as Sporocytophaga congregata A-7. The optimum temperature and pH for cellulase production were 30℃ and 6.0, and the optimum temperature, pH and heat stability of the enzyme were 50℃. 7.0 and below 55℃. When the bacteria was cultured in fermentor, the specific growth race was 0.034hr^(-1) and when the bacteria was mixed cultured with Candida guilliermondii var. guilliermondii, the specific growth rate of the bacteria and yeast were 0. 06hr^(-1) and 0. 08hr^(-1) respectively and total cell dry weight was 4∼5g/ℓ.