Comparative Studies On The Morphological Characteristics And CMCase Properties Of Two Strains Of Aerobic Cellulose Decomposing Bacteria

Sporocytophaga is a kind of bacteria that can decompose the cellulose efficiently. But with the method of determining the fungus cellulase activity, we can only get lower CMCase activity. In this study, we compared the morphological characteristics of the bacteria during the process of decomposing the cellulose, the effects of different media on the CMCase production and the characteristics of the CMCase when decomposing filter paper. We made a comparison between two Sporocytophaga strains, JL-01 and SD-02, in order to get a reasonable explanation about the mechanism of their decomposing the cellulose. The main results are as follow: 1. When the carbon source was cellulose, the cells got thinned and lengthened. It would be the most important state in the process of decomposing cellulose, when the cells could decompose the cellulose. And then the glid cell turned to be a cucloidal dormancy body – sporocyst. The difference of JL-01 and SD-02 was that the sporocyst of the JL-01 cell was observed at one end or the middle while the sporocyst of SD-02 formed after equipartition. 2. The fermentation broth and the culture filtrate of JL-01 displayed higher CMCase activity but lower in cellular exudates and none in the cell residue. The CMCase activity of SD-02 in the fermentation broth and the culture filtrate was a little lower than that of JL-01.The CMCase activity in the cellular exudates of SD-02 was lower than that in the culture filtrate, even less in the cell residue. 3. In FP medium, cellobiose inhibited the CMCase activity when the cellobiose concentration was higher than 15 mmol/L to JL-01, and the cellobiose concentration was higher than 20 mmol/L to SD-02 respectively. When the cellobiose concentration to JL-01 was 1 mmol/L, CMCase production increased. When the nitrogen source was NH4NO3 or yeast powder, the CMCase activity of both strains was higher. However, the CO (NH2) 2 or (NH4) SO4 inhibited the CMCase activity. The two strains did not decompose the cotton fibre and cornstalk apparently; expect that SD-02 decomposed cotton fibre a little. In contrast, when cellobiose was added, they could decompose the cornstalk effectively. 4. Data from the SDS-PAGE indicated that the molecular weight of CMCase-E1 of JL-01 was 84 KDa, and the two CMCase isoenzymes of SD-02 were 89 KDa and 75 KDa. The range of optimal temperatures and pH of these CMCase for cellulose hydrolysis was 35 to 50 and 4.5-6.0. The results showed that Zn²⁺ had an obvious negative effect and Fe²⁺ had a weak positive effect on the CMCase of the two strains. Mg²⁺ inhibited the activity of the CMCase of SD-02 weakly.