Breeding Of β-Mannanase-Producing Strains And The Study Of The Fermentation Condictions

By using the methods of enriching culture, isolation and selective plate culture, 200 P-mannanase producing strains were isolated from the mixture containing konjak, spirit taro, soil, sea water, which were gathered from nature. 20 strains of high enzyme activity were got after the first screening by observing the clear circles on selective plates. Then the strain C3 with the highest enzyme activity of 15.66U/mL was got after the second screening by shaking culture. Comparative 16S rDNA sequence analyses revealed that C3 was most related to the strain Bacillus subtilis (Identities = 100%).To enhance the enzyme activity of C3, mutagenesis of ⁶⁰Co was adopted. Then the screening methods were used again and one strain (N40) with the highest enzyme activity of 31.89U/mL, 2.04 times as its parent strain, was obtained. Then 3 times of ultraviolet mutagenesis were adopted, but unfortunately, no strain of higher enzyme activity was got.The optimal fermentation conditions for producing P-mannanase by strain...