Objective To isolate, incubate, and identify 4-chlorophenol-degrading complex bacteria, determine the tolerance of these bacteria to phenolic derivatives and study their synergetic metabolism as well as the aboriginal...Objective To isolate, incubate, and identify 4-chlorophenol-degrading complex bacteria, determine the tolerance of these bacteria to phenolic derivatives and study their synergetic metabolism as well as the aboriginal microbes and co-metabolic degradation of mixed chlorophenols in river water. Methods Microbial community of complex bacteria was identified by plate culture observation techniques and Gram stain method. Bacterial growth inhibition test was used to determine the tolerance of complex bacteria to toxicants. Biodegradability of phenolic derivatives was determined by adding 4-chlorophenol-degrading bacteria in river water. Results The complex bacteria were identified as Mycopiana, Alcaligenes, Pseudomonas, and Flavobacterium. The domesticated complex bacteria were more tolerant to phenolic derivatives than the aboriginal bacteria from Qinhuai River. The biodegradability of chlorophenols, dihydroxybenzenes and nitrophenols under various aquatic conditions was determined and compared. The complex bacteria exhibited a higher metabolic efficiency on chemicals than the aboriginal microbes, and the final removal rate of phenolic derivatives was increased at least by 55% when the complex bacteria were added into river water. The metabolic relationship between dominant mixed bacteria and river bacteria was studied. Conclusion The complex bacteria domesticated by 4-chlorophenol can grow and be metabolized to take other chlorophenols, dihydroxybenzenes and nitrophenols as the sole carbon and energy source. There is a synergetic metabolism of most compounds between the aboriginal microbes in river water and the domesticated complex bacteria, 4- chlorophenol-degrading bacteria can co-metabolize various chlorophenols in fiver water.展开更多
We study the photo-oxidation of bacteriochlorophylls （BChls） in peripheral light harvesting complexes （LH2） from rhodobacter sphaeroides by using the steady absorption and the femtosecond pump-probe measurement, t...We study the photo-oxidation of bacteriochlorophylls （BChls） in peripheral light harvesting complexes （LH2） from rhodobacter sphaeroides by using the steady absorption and the femtosecond pump-probe measurement, to realize the detailed dynamics of LH2 in the presence of photo-oxidation. The experimental results reveal that BChl-B850 radical cations may act as an additional channel to compete with the unoxidized BChl-B850 molecules for rapidly releasing the excitation energy, while the B800→B850 energy transfer rate is almost unaffected in the oxidation process.展开更多
Purpose: Currently, bacteriological examinations of implant treatments target periodontopathic bacteria such as red complex bacteria, including Porphyromonas gingivalis, and detect them qualitatively or quantitatively...Purpose: Currently, bacteriological examinations of implant treatments target periodontopathic bacteria such as red complex bacteria, including Porphyromonas gingivalis, and detect them qualitatively or quantitatively. However, it seems that those examinations do not reflect the peri-implant tissue conditions precisely, because periodontopathic bacteria are also frequently detected from healthy peri-implant sites. The purpose of the present study was to investigate bacteria species most involved in peri-implantitis using a PCR method. Methods: Polymerase chain reaction (PCR) primers in this study were designed based on partial sequences of 16S rDNA of bacteria species involved in peri-implantitis that were described in numerous previous studies. Peri-implant sulcus fluid (PISF) samples were collected from thirty periodontally healthy patients with implants (HI) and thirty patients with peri-implantitis (PI). Each detection frequency of bacteria species in PISFs of both groups was investigated using a PCR method, and was compared using Fisher’s exact test. Results: In PI group, detection frequencies of Corynebacterium durum, Fretibacterium fastidiosum and Slackia exigua were significantly higher than those of HI group (p P. gingivalis and Tannerella forsythia belonging to red complex were frequently detected in the PISF samples of HI group (p > 0.05). Conclusion: It was suggested that monitoring C. durum and F. fastidiosum levels in PISF samples was useful as a clinical indicator for the evaluation of peri-implant tissue conditions.展开更多
土壤砷污染是全球共同面临的环境问题,砷与土壤有机质结合形成的二元络合物[OM-As(Ⅴ)]是砷在土壤中的主要赋存形式之一。然而,在土壤砷还原菌作用下,OM-As(Ⅴ)中砷的迁移转化过程及机制目前仍不明确。研究以OM-As(Ⅴ)为对象,将其与典...土壤砷污染是全球共同面临的环境问题,砷与土壤有机质结合形成的二元络合物[OM-As(Ⅴ)]是砷在土壤中的主要赋存形式之一。然而,在土壤砷还原菌作用下,OM-As(Ⅴ)中砷的迁移转化过程及机制目前仍不明确。研究以OM-As(Ⅴ)为对象,将其与典型砷还原菌Desulfitobacterium sp.DJ-3共同培养,通过液相化学分析及同步辐射技术,系统分析络合态砷的还原释放过程。结果显示,DJ-3菌株显著促进了OM-As(Ⅴ)中砷的还原(67%)和释放(25%)。砷K-边X射线吸收近边结构(X-ray Absorption Near the Edge Structure,XANES)光谱的线性组合拟合(Linear Combination Fitting,LCF)结果显示,DJ-3菌株能直接将有机质络合态As(Ⅴ)还原为络合态As(Ⅲ),144 h后50%的砷以OM-As(Ⅲ)的形式存在,且该过程会导致部分络合态As(Ⅲ)释放为游离态As(Ⅲ)。研究首次揭示了砷还原菌对二元络合物OM-As(Ⅴ)中砷的还原释放机制,为全面了解土壤砷的迁移转化作用提供了科学依据。展开更多
基金supported by 973 Program (No. 2008CB418203)New Century Excellent Talents in University (No. 05-0481)
文摘Objective To isolate, incubate, and identify 4-chlorophenol-degrading complex bacteria, determine the tolerance of these bacteria to phenolic derivatives and study their synergetic metabolism as well as the aboriginal microbes and co-metabolic degradation of mixed chlorophenols in river water. Methods Microbial community of complex bacteria was identified by plate culture observation techniques and Gram stain method. Bacterial growth inhibition test was used to determine the tolerance of complex bacteria to toxicants. Biodegradability of phenolic derivatives was determined by adding 4-chlorophenol-degrading bacteria in river water. Results The complex bacteria were identified as Mycopiana, Alcaligenes, Pseudomonas, and Flavobacterium. The domesticated complex bacteria were more tolerant to phenolic derivatives than the aboriginal bacteria from Qinhuai River. The biodegradability of chlorophenols, dihydroxybenzenes and nitrophenols under various aquatic conditions was determined and compared. The complex bacteria exhibited a higher metabolic efficiency on chemicals than the aboriginal microbes, and the final removal rate of phenolic derivatives was increased at least by 55% when the complex bacteria were added into river water. The metabolic relationship between dominant mixed bacteria and river bacteria was studied. Conclusion The complex bacteria domesticated by 4-chlorophenol can grow and be metabolized to take other chlorophenols, dihydroxybenzenes and nitrophenols as the sole carbon and energy source. There is a synergetic metabolism of most compounds between the aboriginal microbes in river water and the domesticated complex bacteria, 4- chlorophenol-degrading bacteria can co-metabolize various chlorophenols in fiver water.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10274013 and 10374020.
文摘We study the photo-oxidation of bacteriochlorophylls （BChls） in peripheral light harvesting complexes （LH2） from rhodobacter sphaeroides by using the steady absorption and the femtosecond pump-probe measurement, to realize the detailed dynamics of LH2 in the presence of photo-oxidation. The experimental results reveal that BChl-B850 radical cations may act as an additional channel to compete with the unoxidized BChl-B850 molecules for rapidly releasing the excitation energy, while the B800→B850 energy transfer rate is almost unaffected in the oxidation process.
文摘Purpose: Currently, bacteriological examinations of implant treatments target periodontopathic bacteria such as red complex bacteria, including Porphyromonas gingivalis, and detect them qualitatively or quantitatively. However, it seems that those examinations do not reflect the peri-implant tissue conditions precisely, because periodontopathic bacteria are also frequently detected from healthy peri-implant sites. The purpose of the present study was to investigate bacteria species most involved in peri-implantitis using a PCR method. Methods: Polymerase chain reaction (PCR) primers in this study were designed based on partial sequences of 16S rDNA of bacteria species involved in peri-implantitis that were described in numerous previous studies. Peri-implant sulcus fluid (PISF) samples were collected from thirty periodontally healthy patients with implants (HI) and thirty patients with peri-implantitis (PI). Each detection frequency of bacteria species in PISFs of both groups was investigated using a PCR method, and was compared using Fisher’s exact test. Results: In PI group, detection frequencies of Corynebacterium durum, Fretibacterium fastidiosum and Slackia exigua were significantly higher than those of HI group (p P. gingivalis and Tannerella forsythia belonging to red complex were frequently detected in the PISF samples of HI group (p > 0.05). Conclusion: It was suggested that monitoring C. durum and F. fastidiosum levels in PISF samples was useful as a clinical indicator for the evaluation of peri-implant tissue conditions.
文摘土壤砷污染是全球共同面临的环境问题,砷与土壤有机质结合形成的二元络合物[OM-As(Ⅴ)]是砷在土壤中的主要赋存形式之一。然而,在土壤砷还原菌作用下,OM-As(Ⅴ)中砷的迁移转化过程及机制目前仍不明确。研究以OM-As(Ⅴ)为对象,将其与典型砷还原菌Desulfitobacterium sp.DJ-3共同培养,通过液相化学分析及同步辐射技术,系统分析络合态砷的还原释放过程。结果显示,DJ-3菌株显著促进了OM-As(Ⅴ)中砷的还原(67%)和释放(25%)。砷K-边X射线吸收近边结构(X-ray Absorption Near the Edge Structure,XANES)光谱的线性组合拟合(Linear Combination Fitting,LCF)结果显示,DJ-3菌株能直接将有机质络合态As(Ⅴ)还原为络合态As(Ⅲ),144 h后50%的砷以OM-As(Ⅲ)的形式存在,且该过程会导致部分络合态As(Ⅲ)释放为游离态As(Ⅲ)。研究首次揭示了砷还原菌对二元络合物OM-As(Ⅴ)中砷的还原释放机制,为全面了解土壤砷的迁移转化作用提供了科学依据。
