Abstract

Six Bacillus subtilis strains (CD-3, CD-6, CD-9, CD-10, CD-23 and CD-25) that produce β-mannanase were separated from the Konjacflour plant, Tin, in the Yunnan province of China. The optimal temperatures of the 6 β-mannanases ranged from 45 to 65°C and their optimal pH ranged from 5.0 to 6.5; showing significant differences. The genes of the β-mannanase from 6 B. subtilis were amplified and sequenced. Except for CD-6, the genes shared the great homology (above 98%) with the B. subtilis β-mannanase gene deposited in GenBank. The β-mannanase gene sequence of CD-6 showed the highest homology with the sequence of β-mannanase of Bacillus sp. 5H, but the homology was only 70%. Alignment of the amino acid sequences of the 6 genes indicated that the 6 amino acid sequences shared near total homology with that of the B. subtilis β-mannanase sequence in GenBank. The homology between the amino acid sequence of CD-6 and that of β-mannanase of Bacillus sp. 5H was 72%. The homologies of the other five strains were all above 99%. The 6 amino acid sequences showed a high degree of conservation and the 2 most similar were CD-3 and CD-10, with a similarity of 99.5%.

Key words: β-mannanase, enzyme characterization, gene cloning.