Isolation and identification of a cellulase-producing bacteria and preliminary study on its fermentation conditions

Cytological staining, physiological and biochemical characteristics, and 16S rRNA gene sequences analysis were utilized to identify cellulase-producing bacteria X-6, which was isolated from root soils of the different water yams in Yam Germplasm Resources of Hainan University. Then orthogonal experiment designs were applied to study the effects of incubation time, temperature, pH and ratio of carbon-nitrogen on the cellulase-producing enzyme activity of X-6. The results showed that the strain X-6 was identified as Bacillus cereus, with Gram-positive, amylase-positive, gelatinasepositive and spore in the middle of the bacterium cell. Its 16S rRNA gene was highly similar to Bacillus cereus JSYM28,and the similarity was 99%. The optimal fermentation conditions were as following value of pH was 7.0, the ratio of carbon-nitrogen was 2：4, the temperature was 42℃ for 72 h. Under the optimal fermentation conditions, CMC and FPA enzyme activity were respectively 137.10 U/mL and 171.07 U/mL.