Bacillus firmus, an antagonistic bacterium isolated from the soil by three_layer agar method,strongly inhibited the growth of three kinds of pathogenetic fungi causing seedling damping_off. By enclosed chamber test,th...Bacillus firmus, an antagonistic bacterium isolated from the soil by three_layer agar method,strongly inhibited the growth of three kinds of pathogenetic fungi causing seedling damping_off. By enclosed chamber test,the inhibitory rates of volatilizable metabolites from B. firmus were 8.43%,9.98%,5.59% against Rhizoctonia solani,Fusarium solani,Pythium sp.;Antagonistic substance which was strongly antagonistic to plant pathology fungi can be produced by \%B. firmus\% after cultured for 3 or 2 days,for example,the inhibitory rates of the nonvolatilizable metabolites from B. firmus were 64.04%,29.59%,99.99% against R. solani,F. solani,Pythium sp. after cultured for 64 h. The scanning electronic microscope revealed that the growth of \%R. solani\% was inhibited by non_volatilizable metabolites from B. firmus, their cells of hyphae were expanded to ellipsoid or globular structure in the top or middle cell of hyphae, some hyphae were broken off, and the cytoplasm oozed out of the cells so that most of hyphae became crinkle and shriveled.展开更多
The process described in the present work uses air supplementation in a fluidized bed reactor containing Bacillus firmus strain 37 immobilized on active bovine bone charcoal, to produce by batch fermentation the enzym...The process described in the present work uses air supplementation in a fluidized bed reactor containing Bacillus firmus strain 37 immobilized on active bovine bone charcoal, to produce by batch fermentation the enzyme CGTase (cyclomaltodextrin-glucanotransferase). Three different aeration rates were evaluated. The maximum CGTase activity was achieved after 120 hours of fermentation with aeration rate of 2 vvm and was equal to 2.48 U/mL. When 0.5 and 1 vvm were used the enzymatic activities achieved 1.1 and 0.57 U/mL, respectively. Bovine bone charcoal was characterized in terms of surface area, pore size and volume. To the best of our knowledge, the immobilization of microorganism cells in bovine bone charcoal for CGTase production has not been reported in the literature. Our results showed that fluidized bed reactor allows retaining high concentration of biomass, improving biomass-substrate contact and operation at low residence times, which resulted in improved enzyme production. Therefore, the process as proposed has great potential for industrial development.展开更多
文摘Bacillus firmus, an antagonistic bacterium isolated from the soil by three_layer agar method,strongly inhibited the growth of three kinds of pathogenetic fungi causing seedling damping_off. By enclosed chamber test,the inhibitory rates of volatilizable metabolites from B. firmus were 8.43%,9.98%,5.59% against Rhizoctonia solani,Fusarium solani,Pythium sp.;Antagonistic substance which was strongly antagonistic to plant pathology fungi can be produced by \%B. firmus\% after cultured for 3 or 2 days,for example,the inhibitory rates of the nonvolatilizable metabolites from B. firmus were 64.04%,29.59%,99.99% against R. solani,F. solani,Pythium sp. after cultured for 64 h. The scanning electronic microscope revealed that the growth of \%R. solani\% was inhibited by non_volatilizable metabolites from B. firmus, their cells of hyphae were expanded to ellipsoid or globular structure in the top or middle cell of hyphae, some hyphae were broken off, and the cytoplasm oozed out of the cells so that most of hyphae became crinkle and shriveled.
文摘The process described in the present work uses air supplementation in a fluidized bed reactor containing Bacillus firmus strain 37 immobilized on active bovine bone charcoal, to produce by batch fermentation the enzyme CGTase (cyclomaltodextrin-glucanotransferase). Three different aeration rates were evaluated. The maximum CGTase activity was achieved after 120 hours of fermentation with aeration rate of 2 vvm and was equal to 2.48 U/mL. When 0.5 and 1 vvm were used the enzymatic activities achieved 1.1 and 0.57 U/mL, respectively. Bovine bone charcoal was characterized in terms of surface area, pore size and volume. To the best of our knowledge, the immobilization of microorganism cells in bovine bone charcoal for CGTase production has not been reported in the literature. Our results showed that fluidized bed reactor allows retaining high concentration of biomass, improving biomass-substrate contact and operation at low residence times, which resulted in improved enzyme production. Therefore, the process as proposed has great potential for industrial development.
