Statistical experimental designs were used to optimize the process of phenol degradation by Candida tropicalis Z-04, isolated from phenol-degrading aerobic granules. The most important factors influencing phenol degra...Statistical experimental designs were used to optimize the process of phenol degradation by Candida tropicalis Z-04, isolated from phenol-degrading aerobic granules. The most important factors influencing phenol degradation （p 〈 0.05）, as identified by a two-level Plackett-Burman design with 11 variables, were yeast extract, phenol, inoculum size, and temperature. Steepest ascent method was undertaken to determine the optimal regions of these four significant factors. Central composite design （CCD） and response surface analysis were adopted to further investigate the mutual interactions between these variables and to identify their optimal values that would generate maximum phenol degradation. The analysis results indicated that interactions between yeast extract and temperature, phenol and temperature, inocuhim size and temperature affected the response variable （phenol degradation） significantly. The predicted results showed that the maximum removal efficiency of phenol （99.10%） could be obtained under the optimum conditions of yeast extract 0.41 g/L, phenol 1.03 g/L, inoculum size 1.43% （V/V） and temperature 30.04℃. These predicted values were further verified by validation experiments. The excellent correlation between predicted and experimental values confirmed the validity and practicability of this statistical optimum strategy. This study indicated the excellent ability of C. tropicalis Z-04 in degrading high-strength phenol. Optimal conditions obtained in this experiment laid a solid foundation for further use of this microorganism in the treatment of highstrength phenol effluents.展开更多
Objective To summarize the recent findings on the epidemiology of medically important, opportunistic invasive fungal infections （IFIs） in China and discuss the relevant social, economical reasons and medical factors...Objective To summarize the recent findings on the epidemiology of medically important, opportunistic invasive fungal infections （IFIs） in China and discuss the relevant social, economical reasons and medical factors. Data sources We performed a comprehensive search of both English and Chinese literatures of opportunistic IFIs from China up to April 2012. Study selection Relevant literatures involving researches and cases/case sedes were identified, retrieved and reviewed. Results The incidence of opportunistic IFIs in China was steadily increasing. The incidence and mortality of IFIs were different in patients with various underlying conditions/diseases, from 4.12% to 41.18% and 9.8% to 60.0%, respectively. Candida species, Aspergillus species and Cryptococcus neoformans species complex were the most frequent isolated pathogens. Other uncommon opportunistic IFIs were also been reported, including trichosporonosis, mucormycosis, hyalohyphomycosis （hyaline hyphomycetes） and phaeohyphomycosis （dematiaceous hyphomycetes）. Reports of Chinese patients differed from those of many other countries as there were a higher number of patients without identifiable underlying diseases/conditions. Conclusions Because of the rapid economic development, changing population structure and a growing number of immunocompromised hosts with risk factors, today opportunistic IFIs in China have a significant impact on public health, associated with high morbidity/mortality and higher care costs. Now information related to the epidemiology of opportunistic IFIs in China is still sparse, so we need more organized groups of clinical scientists performing related researches to help the clinicians to obtain more accurate epidemiological characteristics.展开更多
Background The cytochrome P450 lanosterol 14a-demethylase （Ergllp） encoded by ERG11 gene is the primary target for azole antifungals. Changes in azole affinity of this enzyme caused by amino acid substitutions have ...Background The cytochrome P450 lanosterol 14a-demethylase （Ergllp） encoded by ERG11 gene is the primary target for azole antifungals. Changes in azole affinity of this enzyme caused by amino acid substitutions have been reported as a mechanism of azole antifungal resistance. This study aimed to investigate the relationship between amino acid substitutions in Erg11 p from fluconazole resistant Candida a/bicans （C. albicans） isolates and their cross-resistance to azoles. Methods Mutations in ERG11 gene were screened in 10 clinical isolates of fluconazole resistant C. albicans strains. DNA sequence of ERG11 was determined by PCR based DNA sequencing. Results In the 10 isolates, 19 types of amino acid substitutions were found, of which 10 substitutions （F72S, F103L, F1451, F198L, G206D, G227D, N349S, F416S, F422L and T482A） have not been reported previously. Mutations in ERG11 gene were detected in 9 isolates of fluconazole resistant C. albicans, but were not detected in 1 isolate. Conclusions Although no definite correlation was found between the type of amino acid substitutions in Ergllp and the phenotype of cross-resistance to azoles, the substitutions F72S, F1451 and G227D in our study may be highly associated with resistance to azoles because of their special location in Erg11p.展开更多
基金supported by the National Natural Science Foundation of China (No.50778110)
文摘Statistical experimental designs were used to optimize the process of phenol degradation by Candida tropicalis Z-04, isolated from phenol-degrading aerobic granules. The most important factors influencing phenol degradation （p 〈 0.05）, as identified by a two-level Plackett-Burman design with 11 variables, were yeast extract, phenol, inoculum size, and temperature. Steepest ascent method was undertaken to determine the optimal regions of these four significant factors. Central composite design （CCD） and response surface analysis were adopted to further investigate the mutual interactions between these variables and to identify their optimal values that would generate maximum phenol degradation. The analysis results indicated that interactions between yeast extract and temperature, phenol and temperature, inocuhim size and temperature affected the response variable （phenol degradation） significantly. The predicted results showed that the maximum removal efficiency of phenol （99.10%） could be obtained under the optimum conditions of yeast extract 0.41 g/L, phenol 1.03 g/L, inoculum size 1.43% （V/V） and temperature 30.04℃. These predicted values were further verified by validation experiments. The excellent correlation between predicted and experimental values confirmed the validity and practicability of this statistical optimum strategy. This study indicated the excellent ability of C. tropicalis Z-04 in degrading high-strength phenol. Optimal conditions obtained in this experiment laid a solid foundation for further use of this microorganism in the treatment of highstrength phenol effluents.
基金This study was supported by grants from the National Natural Science Foundation of China （No. 31050014） and Academicion Consulting Projects from Chinese Academy of Engineering （No. 2012xy22）.
文摘Objective To summarize the recent findings on the epidemiology of medically important, opportunistic invasive fungal infections （IFIs） in China and discuss the relevant social, economical reasons and medical factors. Data sources We performed a comprehensive search of both English and Chinese literatures of opportunistic IFIs from China up to April 2012. Study selection Relevant literatures involving researches and cases/case sedes were identified, retrieved and reviewed. Results The incidence of opportunistic IFIs in China was steadily increasing. The incidence and mortality of IFIs were different in patients with various underlying conditions/diseases, from 4.12% to 41.18% and 9.8% to 60.0%, respectively. Candida species, Aspergillus species and Cryptococcus neoformans species complex were the most frequent isolated pathogens. Other uncommon opportunistic IFIs were also been reported, including trichosporonosis, mucormycosis, hyalohyphomycosis （hyaline hyphomycetes） and phaeohyphomycosis （dematiaceous hyphomycetes）. Reports of Chinese patients differed from those of many other countries as there were a higher number of patients without identifiable underlying diseases/conditions. Conclusions Because of the rapid economic development, changing population structure and a growing number of immunocompromised hosts with risk factors, today opportunistic IFIs in China have a significant impact on public health, associated with high morbidity/mortality and higher care costs. Now information related to the epidemiology of opportunistic IFIs in China is still sparse, so we need more organized groups of clinical scientists performing related researches to help the clinicians to obtain more accurate epidemiological characteristics.
文摘Background The cytochrome P450 lanosterol 14a-demethylase （Ergllp） encoded by ERG11 gene is the primary target for azole antifungals. Changes in azole affinity of this enzyme caused by amino acid substitutions have been reported as a mechanism of azole antifungal resistance. This study aimed to investigate the relationship between amino acid substitutions in Erg11 p from fluconazole resistant Candida a/bicans （C. albicans） isolates and their cross-resistance to azoles. Methods Mutations in ERG11 gene were screened in 10 clinical isolates of fluconazole resistant C. albicans strains. DNA sequence of ERG11 was determined by PCR based DNA sequencing. Results In the 10 isolates, 19 types of amino acid substitutions were found, of which 10 substitutions （F72S, F103L, F1451, F198L, G206D, G227D, N349S, F416S, F422L and T482A） have not been reported previously. Mutations in ERG11 gene were detected in 9 isolates of fluconazole resistant C. albicans, but were not detected in 1 isolate. Conclusions Although no definite correlation was found between the type of amino acid substitutions in Ergllp and the phenotype of cross-resistance to azoles, the substitutions F72S, F1451 and G227D in our study may be highly associated with resistance to azoles because of their special location in Erg11p.
