Objective:To explore the larvicidal and pupicidal activity of Euphorbia hirta（E.hirta） leaf extract and Bacillus sphaericus（B.sphaericus） against the malarial vector.Anopheles siephensi（An. stephensi）.Methods:Th...Objective:To explore the larvicidal and pupicidal activity of Euphorbia hirta（E.hirta） leaf extract and Bacillus sphaericus（B.sphaericus） against the malarial vector.Anopheles siephensi（An. stephensi）.Methods:The larvicidal and pupicidal activity was assayed against An.stephensi at various concentrations ranging from（75-375 ppm） under the laboratory as well as field conditions. The LC<sub>50</sub> and LC<sub>90</sub> value of the E.hirta leaf extract was determined by probit analysis.Results: The plant extract showed larvicidal effects after 24 h of exposure;however,the highest larval mortality was found in the methanol extract of E.hirta against the first to fourth instars larvae and pupae of values LC<sub>50</sub>=137.40,172.65,217.81,269.37 and 332.39 ppm;B.sphaericus against the first to fourth instars larvae and pupae of values LC<sub>50</sub>= 44.29,55.83,68.51,82.19 and 95.55 ppm, respectively.Moreover,combined treatment of values of LC<sub>50</sub>= 79.13,80.42,86.01,93.00 and 98.12 ppm,respectively.No mortality was observed in the control.Conclusions:These results suggest methanol leaf extracts of E.hirta and B.sphaericus have potential to be used as an ideal ecofriendly approach for the control of the malarial vector.An.stephensi as target species of vector control programs.This study provides the first report on the combined mosquito larvicidal and pupicidal activity of this plant crude extract and bacterial toxin against An.stephensi mosquitoes.展开更多
Objective Assessment of the bacterium L. sphaericus as a dual-action candidate for biological control of mosquito-borne diseases and bioremediation of toxic metals. Methods Larvae of the mosquito, C quinquefasciatus, ...Objective Assessment of the bacterium L. sphaericus as a dual-action candidate for biological control of mosquito-borne diseases and bioremediation of toxic metals. Methods Larvae of the mosquito, C quinquefasciatus, were first evaluated for metal tolerance and then exposed to 5 ppm cadmium, chromium, arsenic, and lead in assays together with seven strains of L. sphaericus. A probit regression analysis was used to estimate the LCso of Cd, Cr, As, and Pb to C. quinquefosciatus. An analysis of covariance and multifactorial ANOVA examined the metal biosorption and larvicidal properties of the seven strains of L. sphaericus. Results We found that L. sphaericus adsorbed the toxic metal ions and was toxic against mosquito larvae. The L. sphoericus strain 111（3）7 resulted in a larvae mortality of over 80% for all the tested metals. This strain also exhibited the capacity to adsorb 76% of arsenic, 32% of lead, 25% of chromium, and 7% of cadmium. Conclusion This study found combined metal adsorption and larval toxicity associated with three strains of L. sphaericus [111（3）7, OT4b.31, and CBAM5]. This suggests that a combination of these strains shows strong dual potential for biological control of mosquitos in heavy metal-contaminated areas and remediate the heavy metal contamination as well.展开更多
Cellulase is an enzyme produced by fungi, bacteria, protozoa and termite, that hydrolyze cellulose. They are known for their diverse applications in industry and medicine. The aim of this study is to purify and invest...Cellulase is an enzyme produced by fungi, bacteria, protozoa and termite, that hydrolyze cellulose. They are known for their diverse applications in industry and medicine. The aim of this study is to purify and investigate cellulolytic properties of cellulase enzyme produced by Bacillus sphaericus CE-3 isolated from refuse dump in Nnamdi Azikiwe University, Awka, Nigeria. Enzyme was produced by submerged fermentation at 30°C for 30 h. The enzyme was purified to homogeneity by dialysis in 4M sucrose solution, ion-exchange chromatography on Q-Sepharose FF and by hydrophobic interaction chromatography on Phenyl Sepharose CL-4B. The relative molecular mass of the enzyme was estimated using SDS-Polyacrylamide gel electrophoresis. Effects of temperature, pH and metals on enzyme activity and stability and the relative rate of hydrolysis of various substrates were also studied. The Purification fold for the enzyme was 7.8, with 66.4 μ/mg specific activity protein and overall yield of 35.8. The relative molecular mass range of the enzyme was estimated between 22.3 kDa - 26.3 kDa. The enzyme was optimally active at pH 9.0 and 40°C, stable at pH 9.0 and unusually retained over 90% activity between 50°C - 100°C after 30 min incubation. It was strongly activated by Mn2+ but inhibited by Ba2+, Co2+, Hg2+, Pb2+, Cu2+, Sr2+, Fe2+, Ca2+ and Zn2+. The cellulase displayed high catalytic activity with untreated sawdust, followed by carboxymethyl cellulose, while sodium hydroxide treated sawdust was the least hydrolyzed. Since the enzyme is thermo-stable, alkalophilic and could utilize natural wastes like sawdust as substrate, it is obvious that it would be of great use in textile, starch processing and pulp and paper industries.展开更多
Objective: To isolate, characterize and evaluate toxicity of Bacillus sphaericus(B. sphaericus) from beach area of Lombok Island.Methods: Soil was collected from determined locations and suspended in sterile physiolog...Objective: To isolate, characterize and evaluate toxicity of Bacillus sphaericus(B. sphaericus) from beach area of Lombok Island.Methods: Soil was collected from determined locations and suspended in sterile physiological saline water. After heat shock was applied, suspension was spread on NYSM agar medium. Colonies grown were then observed and isolated. Colony, cell morphology,and biochemical/physiological characteristics were tested and compared to B. sphaericus2362 as standard. Initial toxicity testing was done against three species of mosquito larvae(Culex quinquefasciatus, Anopheles aconitus and Aedes aegypti) and isolates that showed more than 50% larvae killing will be assayed to obtain LC_(50) and LC_(90)values within 48 h.PCR technique were conducted to obtain 16 s r DNA amplicon for sequencing and to detect toxin-expressing genes(using multiplex PCR).Results: Twenty isolates of B. sphaericus have been collected from 20 determined locations and their characteristics were in agreement with standard B. sphaericus characteristics. Bioassay testing showed that four isolates(namely isolate MNT, SLG, TJL2 and PLG) were mildly toxic against all larvae. The rests were either low toxic or non-toxic at all.Phylogenetic analysis showed that all four isolates were clustered with other known mildly and highly toxic strains. The multiplex PCR result showed four toxic isolates owned 1–2bands from Bin toxin genes and three bands from Mtx toxin genes, whereas 16 isolates with low to non-toxic characteristics showed only three bands from Mtx toxin genes.Conclusions: Four toxic isolates of B. sphaericus were isolated from beach area of Lombok Island. They showed mild toxicity against larvae of three mosquito species.展开更多
为建立潜育化稻田微生物改良技术,采用MWMM(modified wolfe’s mineral medium)培养基富集微好氧FeOB,结合16S rRNA测序等技术鉴定菌株种类,分别采用100 mL 10^(6)(T1)、10^(7)(T2)、10^(8)(T3)CFU/mL菌株发酵液处理潜育化水稻土,评价...为建立潜育化稻田微生物改良技术,采用MWMM(modified wolfe’s mineral medium)培养基富集微好氧FeOB,结合16S rRNA测序等技术鉴定菌株种类,分别采用100 mL 10^(6)(T1)、10^(7)(T2)、10^(8)(T3)CFU/mL菌株发酵液处理潜育化水稻土,评价菌株对潜育化水稻土壤的还原性物质、土壤养分、氮循环功能基因丰度和水稻秧苗生长的影响,并利用16S rRNA高通量测序技术评价该菌株对土壤微生态的影响。结果显示:筛选到的对Fe^(2+)具有较强氧化作用的FeOB为球形赖氨酸芽孢杆菌WH07(Lysinibacillus sphaericus WH07);相比于CK,土壤氧化还原电位(Eh)显著提高(P<0.05),并由负电位转为正电位;T1、T2、T3处理土壤还原性物质总量分别减少26.47%、41.53%、53.19%,亚铁含量分别减少0.37%、21.50%、50.09%,亚锰含量分别减少7.84%、21.57%、37.25%。土壤碱解氮含量分别显著增加15.50%、27.38%、48.90%(P<0.05),速效磷分别显著增加12.52%、17.34%、27.38%(P<0.05),速效钾分别显著增加11.56%、17.20%、19.34%(P<0.05),有机质分别显著增加8.66%、22.22%、45.05%(P<0.05),pH显著分别增加3.40%、8.94%、16.99%(P<0.05)。土壤AOAamoA基因丰度分别增加11.94%、14.68%、33.83%,nosZ基因丰度分别增加42.97%、75.78%、118.75%,nifH基因丰度分别增加38.29%、51.05%、216.13%,UreC基因丰度分别增加16.74%、54.51%、60.94%。水稻株高分别增加5.44%、10.98%、36.00%,叶龄分别增加10.21%、23.42%、36.94%,鲜质量增加分别12.61%、22.52%、28.38%,白根数分别增加10.14%、32.92%、46.81%。土壤微生物多样性指数Chao1和Shannon指数相比于CK均显著降低(P<0.05)。门水平上相对丰度前10的土壤细菌中,有8个显著下调(P<0.05),如Proteobacteria等、2个(Bacteroidetes和Firmicutes)显著上调。在相对丰度前50的属中,3个处理分别有20、19、22个属显著上调(P<0.05),包括Macellibacteroides等6个FeOB;25个属在3个处理中均显著下调(P<0.05),包括MBNT15等4个铁还原菌。调控网络分析显示菌株WH07潜在地与FeOB协同改善土壤理化性质和生物活性,最终促进了秧苗生长。结果表明,应用菌株WH07显著改善了潜育化水稻土壤理化性质,改变了土壤微生物群落结构和功能。展开更多
基金Defence Research & Development Organisation-Life Sciences Research Board, Ministry of Defence,Govt.of India,New Delhi,for providing financial support for the present work
文摘Objective:To explore the larvicidal and pupicidal activity of Euphorbia hirta（E.hirta） leaf extract and Bacillus sphaericus（B.sphaericus） against the malarial vector.Anopheles siephensi（An. stephensi）.Methods:The larvicidal and pupicidal activity was assayed against An.stephensi at various concentrations ranging from（75-375 ppm） under the laboratory as well as field conditions. The LC<sub>50</sub> and LC<sub>90</sub> value of the E.hirta leaf extract was determined by probit analysis.Results: The plant extract showed larvicidal effects after 24 h of exposure;however,the highest larval mortality was found in the methanol extract of E.hirta against the first to fourth instars larvae and pupae of values LC<sub>50</sub>=137.40,172.65,217.81,269.37 and 332.39 ppm;B.sphaericus against the first to fourth instars larvae and pupae of values LC<sub>50</sub>= 44.29,55.83,68.51,82.19 and 95.55 ppm, respectively.Moreover,combined treatment of values of LC<sub>50</sub>= 79.13,80.42,86.01,93.00 and 98.12 ppm,respectively.No mortality was observed in the control.Conclusions:These results suggest methanol leaf extracts of E.hirta and B.sphaericus have potential to be used as an ideal ecofriendly approach for the control of the malarial vector.An.stephensi as target species of vector control programs.This study provides the first report on the combined mosquito larvicidal and pupicidal activity of this plant crude extract and bacterial toxin against An.stephensi mosquitoes.
基金funded by the Research Fund from the Science Faculty of the Universidad de Los Andes and Microbiological Research Center(CIMIC)
文摘Objective Assessment of the bacterium L. sphaericus as a dual-action candidate for biological control of mosquito-borne diseases and bioremediation of toxic metals. Methods Larvae of the mosquito, C quinquefasciatus, were first evaluated for metal tolerance and then exposed to 5 ppm cadmium, chromium, arsenic, and lead in assays together with seven strains of L. sphaericus. A probit regression analysis was used to estimate the LCso of Cd, Cr, As, and Pb to C. quinquefosciatus. An analysis of covariance and multifactorial ANOVA examined the metal biosorption and larvicidal properties of the seven strains of L. sphaericus. Results We found that L. sphaericus adsorbed the toxic metal ions and was toxic against mosquito larvae. The L. sphoericus strain 111（3）7 resulted in a larvae mortality of over 80% for all the tested metals. This strain also exhibited the capacity to adsorb 76% of arsenic, 32% of lead, 25% of chromium, and 7% of cadmium. Conclusion This study found combined metal adsorption and larval toxicity associated with three strains of L. sphaericus [111（3）7, OT4b.31, and CBAM5]. This suggests that a combination of these strains shows strong dual potential for biological control of mosquitos in heavy metal-contaminated areas and remediate the heavy metal contamination as well.
文摘Cellulase is an enzyme produced by fungi, bacteria, protozoa and termite, that hydrolyze cellulose. They are known for their diverse applications in industry and medicine. The aim of this study is to purify and investigate cellulolytic properties of cellulase enzyme produced by Bacillus sphaericus CE-3 isolated from refuse dump in Nnamdi Azikiwe University, Awka, Nigeria. Enzyme was produced by submerged fermentation at 30°C for 30 h. The enzyme was purified to homogeneity by dialysis in 4M sucrose solution, ion-exchange chromatography on Q-Sepharose FF and by hydrophobic interaction chromatography on Phenyl Sepharose CL-4B. The relative molecular mass of the enzyme was estimated using SDS-Polyacrylamide gel electrophoresis. Effects of temperature, pH and metals on enzyme activity and stability and the relative rate of hydrolysis of various substrates were also studied. The Purification fold for the enzyme was 7.8, with 66.4 μ/mg specific activity protein and overall yield of 35.8. The relative molecular mass range of the enzyme was estimated between 22.3 kDa - 26.3 kDa. The enzyme was optimally active at pH 9.0 and 40°C, stable at pH 9.0 and unusually retained over 90% activity between 50°C - 100°C after 30 min incubation. It was strongly activated by Mn2+ but inhibited by Ba2+, Co2+, Hg2+, Pb2+, Cu2+, Sr2+, Fe2+, Ca2+ and Zn2+. The cellulase displayed high catalytic activity with untreated sawdust, followed by carboxymethyl cellulose, while sodium hydroxide treated sawdust was the least hydrolyzed. Since the enzyme is thermo-stable, alkalophilic and could utilize natural wastes like sawdust as substrate, it is obvious that it would be of great use in textile, starch processing and pulp and paper industries.
基金Supported by Ministry of Education and Culture Republic of Indonesia,Directorate General of Higher Education(DGHE)scholarship batch 2012(Grant No.2625/E4.4/2012)
文摘Objective: To isolate, characterize and evaluate toxicity of Bacillus sphaericus(B. sphaericus) from beach area of Lombok Island.Methods: Soil was collected from determined locations and suspended in sterile physiological saline water. After heat shock was applied, suspension was spread on NYSM agar medium. Colonies grown were then observed and isolated. Colony, cell morphology,and biochemical/physiological characteristics were tested and compared to B. sphaericus2362 as standard. Initial toxicity testing was done against three species of mosquito larvae(Culex quinquefasciatus, Anopheles aconitus and Aedes aegypti) and isolates that showed more than 50% larvae killing will be assayed to obtain LC_(50) and LC_(90)values within 48 h.PCR technique were conducted to obtain 16 s r DNA amplicon for sequencing and to detect toxin-expressing genes(using multiplex PCR).Results: Twenty isolates of B. sphaericus have been collected from 20 determined locations and their characteristics were in agreement with standard B. sphaericus characteristics. Bioassay testing showed that four isolates(namely isolate MNT, SLG, TJL2 and PLG) were mildly toxic against all larvae. The rests were either low toxic or non-toxic at all.Phylogenetic analysis showed that all four isolates were clustered with other known mildly and highly toxic strains. The multiplex PCR result showed four toxic isolates owned 1–2bands from Bin toxin genes and three bands from Mtx toxin genes, whereas 16 isolates with low to non-toxic characteristics showed only three bands from Mtx toxin genes.Conclusions: Four toxic isolates of B. sphaericus were isolated from beach area of Lombok Island. They showed mild toxicity against larvae of three mosquito species.
文摘为建立潜育化稻田微生物改良技术,采用MWMM(modified wolfe’s mineral medium)培养基富集微好氧FeOB,结合16S rRNA测序等技术鉴定菌株种类,分别采用100 mL 10^(6)(T1)、10^(7)(T2)、10^(8)(T3)CFU/mL菌株发酵液处理潜育化水稻土,评价菌株对潜育化水稻土壤的还原性物质、土壤养分、氮循环功能基因丰度和水稻秧苗生长的影响,并利用16S rRNA高通量测序技术评价该菌株对土壤微生态的影响。结果显示:筛选到的对Fe^(2+)具有较强氧化作用的FeOB为球形赖氨酸芽孢杆菌WH07(Lysinibacillus sphaericus WH07);相比于CK,土壤氧化还原电位(Eh)显著提高(P<0.05),并由负电位转为正电位;T1、T2、T3处理土壤还原性物质总量分别减少26.47%、41.53%、53.19%,亚铁含量分别减少0.37%、21.50%、50.09%,亚锰含量分别减少7.84%、21.57%、37.25%。土壤碱解氮含量分别显著增加15.50%、27.38%、48.90%(P<0.05),速效磷分别显著增加12.52%、17.34%、27.38%(P<0.05),速效钾分别显著增加11.56%、17.20%、19.34%(P<0.05),有机质分别显著增加8.66%、22.22%、45.05%(P<0.05),pH显著分别增加3.40%、8.94%、16.99%(P<0.05)。土壤AOAamoA基因丰度分别增加11.94%、14.68%、33.83%,nosZ基因丰度分别增加42.97%、75.78%、118.75%,nifH基因丰度分别增加38.29%、51.05%、216.13%,UreC基因丰度分别增加16.74%、54.51%、60.94%。水稻株高分别增加5.44%、10.98%、36.00%,叶龄分别增加10.21%、23.42%、36.94%,鲜质量增加分别12.61%、22.52%、28.38%,白根数分别增加10.14%、32.92%、46.81%。土壤微生物多样性指数Chao1和Shannon指数相比于CK均显著降低(P<0.05)。门水平上相对丰度前10的土壤细菌中,有8个显著下调(P<0.05),如Proteobacteria等、2个(Bacteroidetes和Firmicutes)显著上调。在相对丰度前50的属中,3个处理分别有20、19、22个属显著上调(P<0.05),包括Macellibacteroides等6个FeOB;25个属在3个处理中均显著下调(P<0.05),包括MBNT15等4个铁还原菌。调控网络分析显示菌株WH07潜在地与FeOB协同改善土壤理化性质和生物活性,最终促进了秧苗生长。结果表明,应用菌株WH07显著改善了潜育化水稻土壤理化性质,改变了土壤微生物群落结构和功能。
