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KMID : 0880220110490010086
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Journal of Microbiology
2011 Volume.49 No. 1 p.86 ~ p.93
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Characterization, gene cloning, and heterologous expression of β-mannanase from a thermophilic Bacillus subtilis
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Pijug Summpunn
Suttidarak Chaijan
Duangnate Isarangkul
Suthep Wiyakrutta
Vithaya Meevootisom
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Abstract
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Bacillus subtilis BCC41051 producing a thermostable β-mannanase was isolated from soybean meal-enriched soil and was unexpectedly found to be thermophilic in nature. The extracellular β-mannanase (ManA) produced was hydrophilic, as it was not precipitated even with ammonium sulfate at 80% saturation. The estimated molecular weight of ManA was 38.0 kDa by SDS-PAGE with a pi value of 5.3. Optimal pH and temperature for mannan-hydrolyzing activity was 7.0 and 60°C, respectively. The enzyme was stable over a pH range of 5.0?11.5, and at temperatures of up to 60°C for 30 min, with more than 80% of its activity retained. ManA was strongly inhibited by Hg2+ (1 mM), but was sensitive to other divalent ions to a lesser degree. The gene of ManA encoded a protein of 362 amino acid residues, with the first 26 residues identified as a signal peptide. High expression of recombinant ManA was achieved in both Escherichia coli BL21 (DE3) (415.18 U/ml) and B. megaterium UNcat (359 U/ml).
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KEYWORD
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β-mannanase, Bacillus subtilis, characterization, gene expression, thermophilic
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