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
A new bacterial strain DMT-7 capable of selectively desulfurizing dibenzothiophene（DBT） was isolated from diesel contaminated soil.The DMT-7 was characterized and identified as Lysinibacillus sphaericus DMT-7（NCBI ...A new bacterial strain DMT-7 capable of selectively desulfurizing dibenzothiophene（DBT） was isolated from diesel contaminated soil.The DMT-7 was characterized and identified as Lysinibacillus sphaericus DMT-7（NCBI GenBank Accession No.GQ496620） using 16S rDNA gene sequence analysis.The desulfurized product of DBT,2-hydroxybiphenyl（2HBP）,was identified and confirmed by high performance liquid chromatography analysis and gas chromatography-mass spectroscopy analysis respectively.The desulfurization kinetics revealed that DMT-7 started desulfurization of DBT into 2HBP after the lag phase of 24 hr,exponentially increasing the accumulation of 2HBP up to 15 days leading to approximately 60% desulfurization of the DBT.However,further growth resulted into DBT degradation.The induced culture of DMT-7 showed shorter lag phase of 6 hr and early onset of stationary phase within 10 days for desulfurization as compared to that of non-induced culture clearly indicating the inducibility of the desulfurization pathway of DMT-7.In addition,Lysinibacillus sphaericus DMT-7 also possess the ability to utilize broad range of substrates as sole source of sulfur such as benzothiophene,3,4-benzo DBT,4,6-dimethyl DBT,and 4,6-dibutyl DBT.Therefore,Lysinibacillus sphaericus DMT-7 could serve as model system for efficient biodesulfurization of diesel and petrol.展开更多
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A new bacterial strain DMT-7 capable of selectively desulfurizing dibenzothiophene（DBT） was isolated from diesel contaminated soil.The DMT-7 was characterized and identified as Lysinibacillus sphaericus DMT-7（NCBI GenBank Accession No.GQ496620） using 16S rDNA gene sequence analysis.The desulfurized product of DBT,2-hydroxybiphenyl（2HBP）,was identified and confirmed by high performance liquid chromatography analysis and gas chromatography-mass spectroscopy analysis respectively.The desulfurization kinetics revealed that DMT-7 started desulfurization of DBT into 2HBP after the lag phase of 24 hr,exponentially increasing the accumulation of 2HBP up to 15 days leading to approximately 60% desulfurization of the DBT.However,further growth resulted into DBT degradation.The induced culture of DMT-7 showed shorter lag phase of 6 hr and early onset of stationary phase within 10 days for desulfurization as compared to that of non-induced culture clearly indicating the inducibility of the desulfurization pathway of DMT-7.In addition,Lysinibacillus sphaericus DMT-7 also possess the ability to utilize broad range of substrates as sole source of sulfur such as benzothiophene,3,4-benzo DBT,4,6-dimethyl DBT,and 4,6-dibutyl DBT.Therefore,Lysinibacillus sphaericus DMT-7 could serve as model system for efficient biodesulfurization of diesel and petrol.
