In order to get biological drugs with no resistance or toxic side effects and to reduce the use of antibiotics, a strain of Baci//us subtilis was isolated from animal intestine, and the isolate was identified by molec...In order to get biological drugs with no resistance or toxic side effects and to reduce the use of antibiotics, a strain of Baci//us subtilis was isolated from animal intestine, and the isolate was identified by molecular biological method; in vitro an- tibacterial test of the isolate was performed using agar diffusion method; the optimal fermentation condition of the isoJate was screened by conventional culture method; the antibacterial crude protein of the isolate was extracted by saturated ammonium sulfate method; the physicochemical properties of antibacterial crude protein was de- tected by comparison method; The results showed that the isolate was B. subti/is, which had antibacterial effects on Staphy/ococcus aureus, streptococcus and swine erysipelas. The fermentation effect of the isolate was the best under the condition of temperature 30 ~C, pH 7, liquid volume 75 ml/250 ml, inoculation volume 20% and culture time 48 h. The antibacterial effect of the isolate was the best when extract- ed by 80% saturated ammonium sulfate. The antibacterial crude protein had strong resistance to heat and acid. Organic solvent and UV irradiation had some influences on antibacterial crude protein. Proteases had hydrolytic effects on antibacterial crude protein. The isolated B. subti/is can be used to prevent and control the diseases caused by S. aureus, streptococcus and swine erysipelas, and can regulate intesti- nal microecology by adding into expanded feeds.展开更多
[Objective] The stability of antimicrobial active ingredients of Bacillus subtilis B26 was studied. [Method] The Fermentation broth of B. subtilis B26 was passed through porous membrane after centrifugation,70% （NH4...[Objective] The stability of antimicrobial active ingredients of Bacillus subtilis B26 was studied. [Method] The Fermentation broth of B. subtilis B26 was passed through porous membrane after centrifugation,70% （NH4）2SO2 was used to carry out precipitation,and the sterile crude extracts with resistance against Fusarium decemcellulare Brick were still obtained after dialysis. Plate coated perforated method was adopted to detect the treatment stability towards crude extracts on temperature,pH,ultraviolet radiation,organic solvents and protease. [Result] The inhibition diameter of crude extracts of B. subtilis B26 after treatment at 100 ℃ was 78.2% of the treatment at room temperature,but the crude extracts of B. subtilis B26 completely lost their activity after treatment at 121 ℃; the crude extracts of B. subtilis B26 all had antimicrobial activity in the pH value range of 3-10,and the antimicrobial activity was the largest when the pH value was 7.0; when the crude extract of B. subtilis B26 was irradiated by UV light （power 20 W） for 80 min from 40 cm distance away,the antimicrobial activity of which was 78.1% of the control; when it was treated with ether,chloroform,methanol and acetone for 30 min,the antimicrobial activities of crude extracts of B. subtilis B26 were 96.4%,85.7%,82.1% and 81.5% of the control,respectively; when it was treated with proteinase K,trypsin and pepsin,the inhibition diameters of crude extracts of B. subtilis B26 were 15.2,16.2 and 16.3 mm,the antimicrobial activities were 76.7%,81.8% and 83.3% of the control,respectively. [Conclusion] The crude extracts of B. subtilis B26 had higher antimicrobial stability.展开更多
Marine microorganisms are a new source of natural antifouling compounds. In this study, two bacterial strains, Kytococcus sedentarius QDG-B506 and Bacillus cereus QDG-B509, were isolated from a marine biofilm and iden...Marine microorganisms are a new source of natural antifouling compounds. In this study, two bacterial strains, Kytococcus sedentarius QDG-B506 and Bacillus cereus QDG-B509, were isolated from a marine biofilm and identified. The bacteria fermentation broth could exert inhibitory effects on the growth of Skeletonema costatum and barnacle larvae. A procedure was employed to extract and identify the antifouling compounds. Firstly, a toxicity test was conducted by graduated pH and liquid-liquid extraction to determine the optimal extraction conditions. The best extraction conditions were found to be pH 2 and 100% petroleum ether. The EC50 value of the crude extract of K. sedentarius against the test microalgae was 236.7 ± 14.08 μg mL-1, and that of B. cereus was 290.6 ± 27.11 μg mL-1. Secondly, HLB SPE columns were used to purify the two crude extracts. After purification, the antifouling activities of the two extracts significantly increased: the EC50 of the K. sedentarius extract against the test microalgae was 86.4 ± 3.71 μg mL-1, and that of B. cereus was 92.6 ± 1.47 μg mL-1. These results suggest that the metabolites produced by the two bacterial strains are with high antifouling activities and they should be fatty acid compounds. Lastly, GC-MS was used for the structural elucidation of the compounds. The results show that the antifouling compounds produced by the two bacterial strains are myristic, palmitic and octadecanoic acids.展开更多
文摘In order to get biological drugs with no resistance or toxic side effects and to reduce the use of antibiotics, a strain of Baci//us subtilis was isolated from animal intestine, and the isolate was identified by molecular biological method; in vitro an- tibacterial test of the isolate was performed using agar diffusion method; the optimal fermentation condition of the isoJate was screened by conventional culture method; the antibacterial crude protein of the isolate was extracted by saturated ammonium sulfate method; the physicochemical properties of antibacterial crude protein was de- tected by comparison method; The results showed that the isolate was B. subti/is, which had antibacterial effects on Staphy/ococcus aureus, streptococcus and swine erysipelas. The fermentation effect of the isolate was the best under the condition of temperature 30 ~C, pH 7, liquid volume 75 ml/250 ml, inoculation volume 20% and culture time 48 h. The antibacterial effect of the isolate was the best when extract- ed by 80% saturated ammonium sulfate. The antibacterial crude protein had strong resistance to heat and acid. Organic solvent and UV irradiation had some influences on antibacterial crude protein. Proteases had hydrolytic effects on antibacterial crude protein. The isolated B. subti/is can be used to prevent and control the diseases caused by S. aureus, streptococcus and swine erysipelas, and can regulate intesti- nal microecology by adding into expanded feeds.
基金Supported by National Natural Science Foundation of China (31070555)Research Projects for Students Studied Abroad in Shanxi Province(2008-119)+1 种基金Shanxi Agricultural research (20100311001-7)High School Special Project in Shanxi Province~~
文摘[Objective] The stability of antimicrobial active ingredients of Bacillus subtilis B26 was studied. [Method] The Fermentation broth of B. subtilis B26 was passed through porous membrane after centrifugation,70% （NH4）2SO2 was used to carry out precipitation,and the sterile crude extracts with resistance against Fusarium decemcellulare Brick were still obtained after dialysis. Plate coated perforated method was adopted to detect the treatment stability towards crude extracts on temperature,pH,ultraviolet radiation,organic solvents and protease. [Result] The inhibition diameter of crude extracts of B. subtilis B26 after treatment at 100 ℃ was 78.2% of the treatment at room temperature,but the crude extracts of B. subtilis B26 completely lost their activity after treatment at 121 ℃; the crude extracts of B. subtilis B26 all had antimicrobial activity in the pH value range of 3-10,and the antimicrobial activity was the largest when the pH value was 7.0; when the crude extract of B. subtilis B26 was irradiated by UV light （power 20 W） for 80 min from 40 cm distance away,the antimicrobial activity of which was 78.1% of the control; when it was treated with ether,chloroform,methanol and acetone for 30 min,the antimicrobial activities of crude extracts of B. subtilis B26 were 96.4%,85.7%,82.1% and 81.5% of the control,respectively; when it was treated with proteinase K,trypsin and pepsin,the inhibition diameters of crude extracts of B. subtilis B26 were 15.2,16.2 and 16.3 mm,the antimicrobial activities were 76.7%,81.8% and 83.3% of the control,respectively. [Conclusion] The crude extracts of B. subtilis B26 had higher antimicrobial stability.
基金supported by the National Basic Research Program of China (973 program, No. 2010CB735806)
文摘Marine microorganisms are a new source of natural antifouling compounds. In this study, two bacterial strains, Kytococcus sedentarius QDG-B506 and Bacillus cereus QDG-B509, were isolated from a marine biofilm and identified. The bacteria fermentation broth could exert inhibitory effects on the growth of Skeletonema costatum and barnacle larvae. A procedure was employed to extract and identify the antifouling compounds. Firstly, a toxicity test was conducted by graduated pH and liquid-liquid extraction to determine the optimal extraction conditions. The best extraction conditions were found to be pH 2 and 100% petroleum ether. The EC50 value of the crude extract of K. sedentarius against the test microalgae was 236.7 ± 14.08 μg mL-1, and that of B. cereus was 290.6 ± 27.11 μg mL-1. Secondly, HLB SPE columns were used to purify the two crude extracts. After purification, the antifouling activities of the two extracts significantly increased: the EC50 of the K. sedentarius extract against the test microalgae was 86.4 ± 3.71 μg mL-1, and that of B. cereus was 92.6 ± 1.47 μg mL-1. These results suggest that the metabolites produced by the two bacterial strains are with high antifouling activities and they should be fatty acid compounds. Lastly, GC-MS was used for the structural elucidation of the compounds. The results show that the antifouling compounds produced by the two bacterial strains are myristic, palmitic and octadecanoic acids.
