Microorganisms capable of solubilizing and mineralizing phosphorus （P） pools in soils are considered vital in promoting P bioavallability. The study was conducted to screen and isolate inorganic P-solubilizing bacte...Microorganisms capable of solubilizing and mineralizing phosphorus （P） pools in soils are considered vital in promoting P bioavallability. The study was conducted to screen and isolate inorganic P-solubilizing bacteria （IPSB） and organic P-mineralizing bacteria （OPMB） in soils taken from subtropical flooded and temperate non-flooded soils, and to compare inorganic P-solubilizing and organic P-solubilizing abilities between IPSB and OPMB. Ten OPMB strains were isolated and identified as Bacillus cereus and Bacillus megaterium, and five IPSB strains as B. megaterium, Burkholderia caryophyUi, Pseudomonas cichorii, and Pseudomonas syringae. P-solubilizing and -mineralizing abilities of the strains were measured using the methods taking cellular P into account. The IPSB strains exhibited inorganic P-solubilizing abilities ranging between 25.4-41.7 μg P mL^-1 and organic P-mineralizing abilities between 8.2-17.8μg P mL^-1. Each of the OPMB strains also exhibited both solubilizing and mineralizing abilities varying from 4.4 to 26.5 μg P mL^-1 and from 13.8 to 62.8 μg P mL^-1, respectively. For both IPSB and OPMB strains, most of the P mineralized from the organic P source was incorporated into the bacterial cells as cellular P. A significantly negative linear correlation （P 〈 0.05） was found between culture pH and P solubilized from inorganic P by OPMB strains. The results suggested that P solubilization and mineralization could coexist in the same bacterial strain.展开更多
An important filamentous industrial fungus,Rhizopus cohnii(R.cohnii),was used as an efficient biosorbent for removing cadmium from wastewater.The sorption conditions,such as pH,the dose of biomass and the initial conc...An important filamentous industrial fungus,Rhizopus cohnii(R.cohnii),was used as an efficient biosorbent for removing cadmium from wastewater.The sorption conditions,such as pH,the dose of biomass and the initial concentration of cadmium were examined.Two kinds of adsorption models were applied to simulate the biosorption data.The uptake of cadmium was higher in weak acid condition than in strong acid condition.Nearly no sorption of cadmium occurred when the pH value was lower than 2.0. Biosorption isothermal data could be well simulated by both Langmuir and Freundlich models.Langmuir simulation of the biosorption showed that the maximum uptake of cadmium was 40.5 mg/g(0.36 mmol/g)in the optimal conditions,which was higher than many other adsorbents,including biosorbents and activated carbon.In addition,the reusability results showed that after five times of sorption and desorption process,the sorption capacity of R.cohnii could still maintain nearly 80%,confirming its practical application in cadmium treatment.Fourier transform infrared spectrum revealed that carboxyl,amino and hydroxyl groups on biosorbent R.cohnii surface were responsible for the biosorption of cadmium.展开更多
Resistance in insect pests against the endotoxin of Bacillus thuringiensis （Berliner） （Bt） is a major threat to the usefulness of this biopesticide, both used as traditional formulations and in transgenic crops. A...Resistance in insect pests against the endotoxin of Bacillus thuringiensis （Berliner） （Bt） is a major threat to the usefulness of this biopesticide, both used as traditional formulations and in transgenic crops. A crucial requirement for the development of successful resistance management strategies is a molecular understanding of the nature and inheritance of resistance mechanisms. This information can be used to design management strategies that will delay or counteract Bt resistance. The best known Bt resistance mechanism is inactivation of brush border membrane receptors. This type of resistance has a largely recessive mode of inheritance, which has enabled the design of resistance management approaches involving high dose and refuge strategies. Recent observations suggest that other resistance mechanisms are possible, including a mechanism that sequesters the toxin in the gut lumen through inducible immune reactions. The elevated immune status associated with tolerance to the toxin can be transmitted to subsequent generations by a maternal effect, which has implications for resistance management in the field. The high dose/refuge strategy may not be appropriate for the management of these alternative resistance mechanisms and other strategies have to be developed if inducible dominant resistance or tolerance mechanisms occur frequently in the field.展开更多
基金the Scientific Research Foundation for the Returned Overseas Chinese Scholars, the Ministry of Education of the P.R. China.
文摘Microorganisms capable of solubilizing and mineralizing phosphorus （P） pools in soils are considered vital in promoting P bioavallability. The study was conducted to screen and isolate inorganic P-solubilizing bacteria （IPSB） and organic P-mineralizing bacteria （OPMB） in soils taken from subtropical flooded and temperate non-flooded soils, and to compare inorganic P-solubilizing and organic P-solubilizing abilities between IPSB and OPMB. Ten OPMB strains were isolated and identified as Bacillus cereus and Bacillus megaterium, and five IPSB strains as B. megaterium, Burkholderia caryophyUi, Pseudomonas cichorii, and Pseudomonas syringae. P-solubilizing and -mineralizing abilities of the strains were measured using the methods taking cellular P into account. The IPSB strains exhibited inorganic P-solubilizing abilities ranging between 25.4-41.7 μg P mL^-1 and organic P-mineralizing abilities between 8.2-17.8μg P mL^-1. Each of the OPMB strains also exhibited both solubilizing and mineralizing abilities varying from 4.4 to 26.5 μg P mL^-1 and from 13.8 to 62.8 μg P mL^-1, respectively. For both IPSB and OPMB strains, most of the P mineralized from the organic P source was incorporated into the bacterial cells as cellular P. A significantly negative linear correlation （P 〈 0.05） was found between culture pH and P solubilized from inorganic P by OPMB strains. The results suggested that P solubilization and mineralization could coexist in the same bacterial strain.
基金Project(50830301) supported by the National Natural Science Foundation of ChinaProject(50725825) supported by the National Science Fund for Distinguished Young Scholars of China
文摘An important filamentous industrial fungus,Rhizopus cohnii(R.cohnii),was used as an efficient biosorbent for removing cadmium from wastewater.The sorption conditions,such as pH,the dose of biomass and the initial concentration of cadmium were examined.Two kinds of adsorption models were applied to simulate the biosorption data.The uptake of cadmium was higher in weak acid condition than in strong acid condition.Nearly no sorption of cadmium occurred when the pH value was lower than 2.0. Biosorption isothermal data could be well simulated by both Langmuir and Freundlich models.Langmuir simulation of the biosorption showed that the maximum uptake of cadmium was 40.5 mg/g(0.36 mmol/g)in the optimal conditions,which was higher than many other adsorbents,including biosorbents and activated carbon.In addition,the reusability results showed that after five times of sorption and desorption process,the sorption capacity of R.cohnii could still maintain nearly 80%,confirming its practical application in cadmium treatment.Fourier transform infrared spectrum revealed that carboxyl,amino and hydroxyl groups on biosorbent R.cohnii surface were responsible for the biosorption of cadmium.
文摘Resistance in insect pests against the endotoxin of Bacillus thuringiensis （Berliner） （Bt） is a major threat to the usefulness of this biopesticide, both used as traditional formulations and in transgenic crops. A crucial requirement for the development of successful resistance management strategies is a molecular understanding of the nature and inheritance of resistance mechanisms. This information can be used to design management strategies that will delay or counteract Bt resistance. The best known Bt resistance mechanism is inactivation of brush border membrane receptors. This type of resistance has a largely recessive mode of inheritance, which has enabled the design of resistance management approaches involving high dose and refuge strategies. Recent observations suggest that other resistance mechanisms are possible, including a mechanism that sequesters the toxin in the gut lumen through inducible immune reactions. The elevated immune status associated with tolerance to the toxin can be transmitted to subsequent generations by a maternal effect, which has implications for resistance management in the field. The high dose/refuge strategy may not be appropriate for the management of these alternative resistance mechanisms and other strategies have to be developed if inducible dominant resistance or tolerance mechanisms occur frequently in the field.
