A novel saline-tolerant bacterium Bacillus circulans WZ-12 was evaluated for its potential to degrade four chlorinated hydrocarbons under saline conditions. CHECl2 was effectively degraded by Bacillus circulans WZ-12 ...A novel saline-tolerant bacterium Bacillus circulans WZ-12 was evaluated for its potential to degrade four chlorinated hydrocarbons under saline conditions. CHECl2 was effectively degraded by Bacillus circulans WZ-12 cells in the medium containing NaCl concentrations ranging from 5 g.L^-1 to 10 g-L^-1, and the maximum degradation efficiency （85%） was achieved at NaCl concentration of 10 g.L^-1. Similarly, Bacillus circulans WZ-12 was able to degrade CH2BrCl, C2H4Cl2, and C2H2Cl2 in the presence of 10 g NaCl per liter within 24 h. Cells of Bacillus circulans WZ-12 grown in minimal salt medium contained low levels of glycine betaine （GB）, but GB levels were 3- to 5-fold higher in cells grown in media with high salt. Kinetic analysis revealed that biodegradation of the four chlorinated hydrocarbons was concentration dependent and a linear inverse correlation （R2= 0.85-0.94） was observed between the rate of biodegradation （V） and salt concentration from 5 g.L〈 to 60 g.L-1. The growing cells （in minimal salt medium） degraded approximately 50% of the CH2C12 within 24 h, whereas the resting cells （in physiological saline） degraded only 25% of the CH2C12 within 24 h and were inactive after 36 h cultivation. Biodegradation could be repeatedly performed for more than 192 h with more than 50% removal efficiency. Bacillus circulans WZ-12 grows well in an aqueous/oil system, hence, it is effective for the treatment of industriai efflu- ents that contain chlorinated hydrocarbons with high salt concentrations.展开更多
Sequence analysis of the chitinase gene cht1 of Bacillus circulans showed that it contained 2151 nucleotides,which codes the precursor of chitinase CHT1 with 717 amino acid residues.The nucleotide and deduced amino ac...Sequence analysis of the chitinase gene cht1 of Bacillus circulans showed that it contained 2151 nucleotides,which codes the precursor of chitinase CHT1 with 717 amino acid residues.The nucleotide and deduced amino acid sequences of cht1 showed 81% and 95% homology with those of ChiA of B.circulans WL-12,respectively.The cht1 gene was cloned into the Escherichia coli-Bacillus subtilis shuttle vector pSUGV4 and two recombinant plasmids, named pUSCH1 and pUSCH2 which contained 2.9kb and 4.0 kb insert respectively,were obtained.The recombinant plasmids were transformed into B.subtilis DB104 and WB600.Chitinase activity was detected both in transformed E.coli and B.subtilis.The DB104/pUSCH1 strain was found to be effective in the bio-controlling the infection of Magnaporthe grisea under greenhouse condition,which showed 71.67% decrease in rice disease incidence.展开更多
基金Supported by the National Natural Science Foundation of China （20977087, 20976165）, Zhejiang Provincial Key Science and Technology Project of China （2011C13023）, and Zhejiang Provincial Natural Science Foundation of China （Y5090155, Y5090054）.
文摘A novel saline-tolerant bacterium Bacillus circulans WZ-12 was evaluated for its potential to degrade four chlorinated hydrocarbons under saline conditions. CHECl2 was effectively degraded by Bacillus circulans WZ-12 cells in the medium containing NaCl concentrations ranging from 5 g.L^-1 to 10 g-L^-1, and the maximum degradation efficiency （85%） was achieved at NaCl concentration of 10 g.L^-1. Similarly, Bacillus circulans WZ-12 was able to degrade CH2BrCl, C2H4Cl2, and C2H2Cl2 in the presence of 10 g NaCl per liter within 24 h. Cells of Bacillus circulans WZ-12 grown in minimal salt medium contained low levels of glycine betaine （GB）, but GB levels were 3- to 5-fold higher in cells grown in media with high salt. Kinetic analysis revealed that biodegradation of the four chlorinated hydrocarbons was concentration dependent and a linear inverse correlation （R2= 0.85-0.94） was observed between the rate of biodegradation （V） and salt concentration from 5 g.L〈 to 60 g.L-1. The growing cells （in minimal salt medium） degraded approximately 50% of the CH2C12 within 24 h, whereas the resting cells （in physiological saline） degraded only 25% of the CH2C12 within 24 h and were inactive after 36 h cultivation. Biodegradation could be repeatedly performed for more than 192 h with more than 50% removal efficiency. Bacillus circulans WZ-12 grows well in an aqueous/oil system, hence, it is effective for the treatment of industriai efflu- ents that contain chlorinated hydrocarbons with high salt concentrations.
文摘Sequence analysis of the chitinase gene cht1 of Bacillus circulans showed that it contained 2151 nucleotides,which codes the precursor of chitinase CHT1 with 717 amino acid residues.The nucleotide and deduced amino acid sequences of cht1 showed 81% and 95% homology with those of ChiA of B.circulans WL-12,respectively.The cht1 gene was cloned into the Escherichia coli-Bacillus subtilis shuttle vector pSUGV4 and two recombinant plasmids, named pUSCH1 and pUSCH2 which contained 2.9kb and 4.0 kb insert respectively,were obtained.The recombinant plasmids were transformed into B.subtilis DB104 and WB600.Chitinase activity was detected both in transformed E.coli and B.subtilis.The DB104/pUSCH1 strain was found to be effective in the bio-controlling the infection of Magnaporthe grisea under greenhouse condition,which showed 71.67% decrease in rice disease incidence.
