Full Length Research Paper

Characterization of 6 Bacillus subtilis β-mannanases and their genes

Xu Bo^1,2,3#, Duan Lei^1,2#, Tang Xiang-hua^1,2,3, Li Jun-jun^1,2,3, Mu Yue-lin^1,2,3, Yang Yun-juan^1,2,3 and Huang Zunxi^1,2,3*

¹School of Life Science, Yunnan Normal University, Kunming 650092, P.R. China.

²Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment, Yunnan, Kunming, 650092, P.R. China.

³Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming, 650092, P.R. China.

*Corresponding author. E-mail: huangzunxi@163.com.

#These authors contributed equally to this paper

Accepted 17 June, 2009

   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.