KMID : 1094720190240050810
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Biotechnology and Bioprocess Engineering 2019 Volume.24 No. 5 p.810 ~ p.817
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Construction and Application of Low Cellulase-producing Bacillus licheniformis Strains for Bio-pulping of Bamboo
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Xue Le
Han Haihong Fan Han Li Piwu Wang Tengfei Xiao Jing Wang Ruiming Wang Junqing
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Abstract
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To prevent cellulose loss during bio-pulping, two cellulase genes in Bacillus licheniformis 20085 were knocked out by homologous exchange technique. An engineering strain B. licheniformis 20085¥Äcelb was significantly compromised the ability to disintegrate filter paper compared to the original strain. After fermentation for 60 h, the CMCase activity value decreased from 1.86 to 0.50 U/mL, suggesting that the celb gene played an important role in the process of cellulose degradation in B. licheniformis 20085. We also assessed the ability of B. licheniformis 20085¥Äcelb to pulp bamboo. The yield of bamboo pulp was 51.91%, the kappa number was 11.26%, and 1.3% of cellulose was degraded after bio-pulping. Environmental Scanning Electron Microscope (ESEM) studies were also conducted to visualize the effect of these strains on bamboo cell walls. These results indicate that pulping with B. licheniformis 20085¥Äcelb can generate a higher yield and lower kappa number.
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KEYWORD
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B. licheniformis, bio-pulping, gene knockout, enzymatic hydrolysis, environmental scanning electron microscope
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