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1.
Samples of the microbial community from Lake Michie, a mesotrophic reservoir in central North Carolina, were adapted to various levels (100 to 1,000 μg/liter) of natural humic acids in chemostats. The humic acids were extracted from water samples from Black Lake, a highly colored lake in the coastal plain of North Carolina. After adaptation, the microbial community was tested for its ability to degrade the monosubstituted phenols m-cresol, m-aminophenol, and p-chlorophenol. Adaptation to increasing levels of humic acids significantly reduced the ability of the microbial communities to degrade all three phenols. The decline in biodegradation was accompanied by a decrease in the number of specific compound degraders in the adapted communities. Short-term exposure of the community to increasing levels of humic acids had no significant effect on the ability of the community to degrade m-cresol. Thus the suppressive effect of humic acids on monosubstituted phenol metabolism was the result of long-term exposure to the humic materials. Increasing the levels of inorganic nutrients fed to the chemostats during the humic acid adaptation had little effect on the suppressive influence of the humic acids, indicating that nutrient limitation was probably not responsible for the metabolic suppression. The results of the study suggest that long-term exposure to humic acids can reduce the ability of microbial communities to respond to monosubstituted phenols.  相似文献   

2.
The adaptation of a mixed aquatic microbial community to phenol was examined in microcosms receiving phenol as a sole carbon source. Extended exposure (adaptation) to phenol resulted in adaptation of the microbial community to the structurally related aromatic compounds m-cresol, m-aminophenol, and p-chlorophenol. The increased biodegradation potential of the phenol-adapted microbial community was accompanied by a concurrent increase in the number of microorganisms able to degrade the three test compounds. Thus, adaptation to the three test chemicals was likely a growth-related result of extended exposure to phenol. The results indicate that adaptation to a single chemical may increase the assimilative capacity of an aquatic environment for other related chemicals even in the absence of adaptation-inducing levels of those materials.  相似文献   

3.
The ability of subsurface microbial communities to adapt to the biodegradation of xenobiotic compounds was examined in aquifer solids samples from a pristine aquifer. An increase in the rates of mineralization of radiolabeled substrates with exposure was used as an indication of adaptation. For some compounds, such as chlorobenzene and 1,2,4-trichlorobenzene, slight mineralization was observed but no adaptation was apparent during incubations of over 8 months. Other compounds demonstrated three patterns of response. For m-cresol, m-aminophenol, and aniline intermediate rates of biodegradation and a linear increase in the percent mineralized with time were observed. Phenol, p-chlorophenol, and ethylene dibromide were rapidly metabolized initially, with a nonlinear increase in the percent mineralized with time, indicating that the community was already adapted to the biodegradation of these compounds. Only p-nitrophenol demonstrated a typical adaptation response. In different samples of soil from the same layer in the aquifer, the adaptation period to p-nitrophenol varied from a few days to as long as 6 weeks. In most cases the concentration of xenobiotic added, over the range from a few nanograms to micrograms per gram, made no difference in the response. Most-probable-number counts demonstrated that adaptation is accompanied by an increase in specific degrader numbers. This study has shown that diverse patterns of response occur in the subsurface microbial community.  相似文献   

4.
The ability of subsurface microbial communities to adapt to the biodegradation of xenobiotic compounds was examined in aquifer solids samples from a pristine aquifer. An increase in the rates of mineralization of radiolabeled substrates with exposure was used as an indication of adaptation. For some compounds, such as chlorobenzene and 1,2,4-trichlorobenzene, slight mineralization was observed but no adaptation was apparent during incubations of over 8 months. Other compounds demonstrated three patterns of response. For m-cresol, m-aminophenol, and aniline intermediate rates of biodegradation and a linear increase in the percent mineralized with time were observed. Phenol, p-chlorophenol, and ethylene dibromide were rapidly metabolized initially, with a nonlinear increase in the percent mineralized with time, indicating that the community was already adapted to the biodegradation of these compounds. Only p-nitrophenol demonstrated a typical adaptation response. In different samples of soil from the same layer in the aquifer, the adaptation period to p-nitrophenol varied from a few days to as long as 6 weeks. In most cases the concentration of xenobiotic added, over the range from a few nanograms to micrograms per gram, made no difference in the response. Most-probable-number counts demonstrated that adaptation is accompanied by an increase in specific degrader numbers. This study has shown that diverse patterns of response occur in the subsurface microbial community.  相似文献   

5.
The adaptation of an anaerobic culture (anaerobic sludge) to a specific substrate brings significant changes to its microbial population. These changes can be described by the sludge's ability to treat various substrates such as carbohydrates or proteins or "intermediate" products of anaerobic metabolism such as L-lactic, propionic, and acetic acids. The activity of the sludge with respect to a specific substrate is a critical parameter, because the anaerobic degradability of wastewaters depends strongly on it. This work examines and quantifies the differentiation of two anaerobic sludges of the same origin, following an adaptation period of about 18 months to lactose and gelatin, respectively. The acclimation has a significant effect on the maximum specific utilization rates of various compounds and on their apparent consumption kinetics. It is noticeable, however, that even if the anaerobic cultures were not exposed to a specific substrate for a prolonged period of time (more than a year), they still kept the ability of hydrolyzing or degrading it. In addition, the acclimation has an unquestionable effect on the stoichiometry of the production of volatile fatty acids and L-lactate. Finally, from codigestion experiments it is shown that codigestion of lactose and gelatin appears to have no effect on their hydrolysis kinetics in any of the lactose or gelatin acclimated cultures; specifically, the hydrolysis kinetics remained the same as calculated when lactose or gelatin were the only fed substrates. Similarly, the kinetics of L-lactate and D-glucose biodegradation seemed to be unchanged. On the other hand, codigestion has a significant effect on the production of L-lactic, propionic, and acetic acids, which can be attributed to the increased hydrogen production accompanying gelatin biodegradation.  相似文献   

6.
Lengthy adaptation periods in laboratory studies evaluating the potential for contaminant biodegradation in natural or engineered environments may indicate that the native microbial communities are not metabolizing the contaminants in situ. In this study, we characterized the adaptation period preceding the biodegradation of 3-chlorobenzoate in anaerobic communities derived from lake sediment and wastewater sludge digesters. The importance of alternative mechanisms of adaptation of the anaerobic communities to 3-chlorobenzoate was evaluated by monitoring the concentrations of metabolic substrates and products as well as the levels of total small subunit (SSU) rRNA and SSU rRNA from populations thought to be important in 3-chlorobenzoate mineralization. The anaerobic environments from which the 3-chlorobenzoate-degrading communities were derived contained different levels of endogenous substrates. Increasing methane levels in the digester and sediment communities and decreasing chemical oxygen demand concentrations in the sediment community during the adaptation periods revealed that endogenous substrates were preferentially utilized relative to 3-chlorobenzoate. Methane and chemical oxygen demand concentrations leveled off concomitantly with the onset of 3-chlorobenzoate biodegradation, suggesting that depletion of the preferentially degraded endogenous substrates stimulated 3-chlorobenzoate metabolism. Consistent with these observations, adaptation to 3-chlorobenzoate occurred more rapidly in digester samples that were depleted of endogenous substrates compared to samples that contained high levels of these biodegradable compounds. Other potential adaptation mechanisms, e.g., genetic change or selective population enrichment, appeared to be less important based on the reproducibility and relative lengths of the adaptation events, trends in the SSU rRNA levels, and/or amplification of SSU rRNA genes from key populations.  相似文献   

7.
Lengthy adaptation periods in laboratory studies evaluating the potential for contaminant biodegradation in natural or engineered environments may indicate that the native microbial communities are not metabolizing the contaminants in situ. In this study, we characterized the adaptation period preceding the biodegradation of 3-chlorobenzoate in anaerobic communities derived from lake sediment and wastewater sludge digesters. The importance of alternative mechanisms of adaptation of the anaerobic communities to 3-chlorobenzoate was evaluated by monitoring the concentrations of metabolic substrates and products as well as the levels of total small subunit (SSU) rRNA and SSU rRNA from populations thought to be important in 3-chlorobenzoate mineralization. The anaerobic environments from which the 3-chlorobenzoate-degrading communities were derived contained different levels of endogenous substrates. Increasing methane levels in the digester and sediment communities and decreasing chemical oxygen demand concentrations in the sediment community during the adaptation periods revealed that endogenous substrates were preferentially utilized relative to 3-chlorobenzoate. Methane and chemical oxygen demand concentrations leveled off concomitantly with the onset of 3-chlorobenzoate biodegradation, suggesting that depletion of the preferentially degraded endogenous substrates stimulated 3-chlorobenzoate metabolism. Consistent with these observations, adaptation to 3-chlorobenzoate occurred more rapidly in digester samples that were depleted of endogenous substrates compared to samples that contained high levels of these biodegradable compounds. Other potential adaptation mechanisms, e.g., genetic change or selective population enrichment, appeared to be less important based on the reproducibility and relative lengths of the adaptation events, trends in the SSU rRNA levels, and/or amplification of SSU rRNA genes from key populations.  相似文献   

8.
The capacity to utilize carbon substrates is fundamental to the functioning of heterotrophic microbial communities in aquatic environments. Carbon-source utilization within the water column, however, is not a bulk property because microbial communities are patchily distributed on suspended organic aggregates (i.e., marine snow, marine aggregates, river aggregates, organic detritus, and bioflocs). In this study, Biolog Ecoplates were used to evaluate the metabolic capacity of heterotrophic bacterial communities associated with aggregates compared to communities in the surrounding water. Overall, aggregate-associated microbial communities demonstrated higher levels of metabolism, metabolic versatility, and functional redundancy, and a more consistent pattern of carbon-source utilization compared with water-associated communities. In addition, aggregate-associated communities more effectively exploited available resources, including representatives from several biochemical guilds and nitrogen-containing carbon sources. Within the aggregate-associated microbial community, metabolic activity was significantly higher in the presence of polymers, amino acids, and carbohydrates relative to amines and carboxylic acids. In comparison, metabolic activity of water-associated communities exceeded a threshold value for only two of the five guilds (polymers and carbohydrates) evaluated. These results suggest that compared with their free-living counterparts, aggregate-associated communities have a greater capacity to respond to a wider array of carbon inputs. Results also underscore the importance of targeting organic aggregates to better understand the role of microbial processes in ecosystem functioning.  相似文献   

9.
An internal loop airlift reactor (ILALR) is developed and studied for biodegradation of phenol/m-cresol as single and dual substrate systems under batch and fed batch operation using an indigenous mixed microbial strain, predominantly Pseudomonas sp. The results showed that the culture could degrade phenol/m-cresol completely at a maximum concentration of 600mgl(-1) and 400mgl(-1), respectively. Batch ILALR study has revealed that phenol has been preferentially degraded by the microbial culture rather than m-cresol probably owing to the toxic effect of the later. Sum kinetic model evaluated the interaction between the phenol/m-cresol in dual substrate system, which resulted in a high coefficient of determination (R(2)) value >0.98). The fed batch results showed that the strain was able to degrade phenol/m-cresol with maximum individual concentrations 600mgl(-1) each in 26h and 37h, respectively. Moreover for fed batch operation, degradation rates increased with increase in feed concentration without any lag in the degradation profile.  相似文献   

10.
刺参池塘底质微生物群落功能多样性的季节变化   总被引:4,自引:0,他引:4  
闫法军  田相利  董双林  阳钢  刘瑞娟  张凯 《生态学报》2014,34(11):2996-3006
利用BIOLOG技术和冗余分析(Redundancy analysis,RDA)方法对刺参(Apostichopus japonicus)养殖池塘底质环境(底泥、附着基)微生物群落功能多样性的季节变化及其与环境因子的关系进行了研究。结果表明:(1)刺参池塘底泥和附着基微生物对碳源总量和单类碳源的利用均具有显著的季节变化,总体表现为春、夏、秋季节高于冬季,其中,底泥微生物利用比例较高的碳源类型为聚合物、糖类、羧酸和氨基酸,附着基微生物利用比例较高的碳源类型为聚合物、糖类、氨基酸和胺。(2)主成分分析表明,刺参池塘底泥和附着基微生物碳代谢方式均具有显著的季节变化。底泥中,与主成分显著相关的碳源有18种,其中与主成分1显著相关的主要是糖类、羧酸和氨基酸,与主成分2显著相关的主要是聚合物和糖类;附着基中,与主成分显著相关的碳源有22种,其中与主成分1显著相关的主要是聚合物、糖类、羧酸和氨基酸,与主成分2显著相关的是羧酸。(3)刺参池塘底泥和附着基微生物多样性指数Shannon、McIntosh、Simpson和S-E均匀度均存在显著的季节变化,但不同指数之间的变化有较大差异。(4)RDA分析表明,TP、NO3-N和PO4-P是影响底泥微生物功能多样性季节变化的主要因素,SOM、NO3-N和TN是影响附着基微生物功能多样性季节变化的主要因素。结论认为,刺参池塘底泥和附着基微生物功能多样性具有显著的不同的季节变化,这些变化与环境因子具有很好的相关性。  相似文献   

11.
The influence of spatial and temporal environmental variations on rates of organic pollutant biodegradation were assessed by using heterotrophic uptake kinetics. These studies were conducted at three sites, representing the gradient from freshwater to estuarine to marine systems. Of the compounds tested, total uptake Vmax rates decreased in the order of nitrilotriacetic acid, m-cresol, chlorobenzene, and 1,2,4-trichlorobenzene. In general, the freshwater site exhibited the highest uptake rates, with somewhat lower rates at the estuarine site. Rates at the marine site were much lower than at the other sites, except during the winter. Metabolic rates at both the freshwater and estuarine areas were significantly decreased during periods of low water temperature. Rates at the marine site were relatively uniform throughout the year. Linear regression analysis was used to compare m-cresol biodegradation rates to characteristics of the microbial community, which included direct microscopic counts, CFU counts, and cellular incorporation of amino acids. The observed rates did not consistently correlate well with any of the measured characteristics of the microbial community.  相似文献   

12.
不同干扰方式下松江湿地土壤微生物群落结构和功能特征   总被引:1,自引:0,他引:1  
以松江湿地为研究对象,采用磷脂脂肪酸(PLFA)和BIOLOG微平板法,系统分析4种干扰方式(农业、工业、旅游和保护)对湿地土壤微生物群落结构和功能的影响。结果表明,微生物对碳源利用能力由强到弱依次为:滨江湿地(保护)金河湾湿地(旅游)白鱼泡湿地(旅游)太阳岛湿地(旅游)呼兰河口湿地(农业)阿什河湿地(工业)。松江湿地土壤微生物对羧酸类、糖类和氨基酸类碳源利用率较高,而对多聚物类、酚类和胺类的利用率较低,其中羧酸类和糖类是影响微生物群落代谢功能的敏感碳源。松江湿地土壤微生物以细菌为主,占总PLFA的69.72%—80.97%,真菌次之(9. 20%—23. 51%),放线菌最少(6.77%—9.82%); Shannon多样性指数以滨江湿地最高(2.994),阿什河湿地最低(2.881)。RDA分析表明,受工业、农业干扰的阿什河湿地和呼兰河口湿地微生物群落结构与TN、NO_3~--N和NH_4~+-N呈显著正相关(P0.05);受旅游干扰的太阳岛湿地微生物群落结构与pH呈显著正相关;而同样受旅游干扰的白鱼泡和金河湾湿地微生物群落结构与p H呈显著负相关;受保护的滨江湿地微生物群落结构主要受TC/TN影响。  相似文献   

13.
The catabolic and energy metabolism capacities during spotted wolffish (Anarhichas minor) embryogenesis were investigated. We assessed the embryo's ability to catabolize proteins (trypsin-like proteases) and lipids (triglyceride lipase) and examined the development of metabolic capacities using enzymatic assays: ability to use carbohydrates (pyruvate kinase), amino acids (aspartate aminotransferase) and fatty acids (hydroxyacyl-CoA dehydrogenase) for energy production, and aerobic (citrate synthase) and anaerobic (lactate dehydrogenase) energy production. Functional enzymatic systems were detected from the eyed stage (350 degree-days), except for fatty acids, which was detected from 540 degree-days. To compare the development of 1) aerobic and anaerobic pathways and 2) the capacity to mobilize the different energy substrates, enzymatic ratios were calculated. Anaerobic capacity appeared to increase at a significantly higher rate than the aerobic capacity. Ratios revealing the relative capacity to use specific energy substrates showed a significantly slower increase during development in the capacity to use carbohydrates than amino acids and fatty acids. The end of embryogenesis was characterized by a significant decrease in the use of carbohydrates for aerobic energy production but an increasing capacity to use amino acids. Egg survival as affected by the variability in metabolic parameters is discussed.  相似文献   

14.
Anaerobic microbial conversion of organic substrates to various biofuels is one of the alternative energy sources attracting the greatest attention of scientists. The advantages of biogas production over other technologies are the ability of methanogenic communities to degrade a broad range of substrates and concomitant benefits: neutralization of organic waste, reduction of greenhouse gas emission, and fertilizer production. Cellulose-containing materials are good substrate, but their full-scale utilization encounters a number of problems, including improvement of the quality and amount of biogas produced and maintenance of the stability and high efficiency of microbial communities. We review data on microorganisms that form methanogenic cellulolytic communities, enzyme complexes of anaerobes essential for cellulose fiber degradation, and feedstock pretreatment, as biodegradation is hindered in the presence of lignin. Methods for improving biogas production by optimization of microbial growth conditions are considered on the examples of biogas formation from various types of plant and paper materials: office paper and cardboard.  相似文献   

15.
运用Biolog EcoPlate技术, 对武夷山不同海拔植被带(常绿阔叶林(EBF)、针叶林(CF)、亚高山矮林(DF)、高山草甸(AM))土壤微生物群落多样性差异进行了研究。结果表明: 不同海拔植被带土壤微生物群落功能多样性差异显著。土壤平均颜色变化率(AWCD)随培养时间延长而逐渐增加, 同一深度土层的AWCD值随海拔升高而逐渐降低, 大小顺序依次为EFB > CF > DF > AM。同一海拔植被带, 不同深度土层的AWCD值总体趋势依次为0-10 cm > 10-25 cm > 25-40 cm。土壤微生物群落Simpson指数、Shannon-Wiener指数、丰富度指数和McIntosh指数的总体趋势为EBF最高, CF和DF次之, AM最低。不同海拔植被带土壤微生物对不同碳源利用强度存在较大差异, 其中EBF利用率最高, AM利用率最低, 碳水化合物和羧酸类碳源是各海拔植被带土壤微生物的主要碳源。主成分分析结果表明, 从31个因素中提取的与碳源利用相关的主成分1、主成分2分别能解释变量方差的75.27%和16.14%, 在主成分分离中起主要贡献作用的是胺类和氨基酸类碳源。土壤微生物群落多样性随着海拔上升、土层加深而逐渐下降的原因, 可能是生物量、林分凋落物、土壤养分、微小动物、植物根系等多种因素共同作用的结果。  相似文献   

16.
The kinetics of biodegradation of palm-derived fatty methyl and ethyl esters (Elaeis guineensis biodiesel) by a wild-type aerobic bacterial population was measured at 20 degrees C, as the rate of oxygen uptake by a manometric technique. The methyl and ethyl biodiesels were obtained by potassium-hydroxide catalysed trans-esterification of palm oil, respectively. The bacterial flora included the genera Bacillus, Proteus, Pseudomonas, Citrobacter and Enterobacter. The rate of oxygen uptake for palm biodiesel is similar to the quantity observed in the biodegradation of 1.0 mM solutions of simple substrates such as carbohydrates or amino acids. Palm methyl or ethyl biodiesel is subjected to facile aerobic biodegradation by wild-type bacteria commonly present in natural open environments. This result should lessen any environmental concern for its use as alternative fuel, solvent or lubricant.  相似文献   

17.
Several strains belonging to genera Pseudomonas and Achromobacter and characterized by the ability to degrade anionic surfactants were tested as potential bases of microbial biosensors for surfactant detection. For each strain the substrate specificity and stability of sensor signals were studied. The total amount of the substrates tested (including carbohydrates, alcohols, aromatics, organic acids, etc.) was equal to 60; the maximal signals were observed towards the anionic surfactants. The lower limit of detection for sodium dodecyl sulfate used as a model surfactant was in the field of 1 microM for all the strains. The created microbial biosensor model can extend the practical possibilities for rapid evaluation of surfactants in water media.  相似文献   

18.
氨基酸对青稞酒酿造微生物群落演替及风味代谢的驱动   总被引:1,自引:1,他引:0  
【背景】环境因素是微生物生长代谢的重要驱动因素,因此,解析其对白酒酿造过程中微生物群落演替的影响对青稞酒的可控化生产具有重要作用。氨基酸作为微生物生长代谢的重要营养底物以及环境因素,其对微生物群落演替的作用尚不明确。【目的】揭示环境因素对青稞酒发酵过程中微生物群落演替及风味代谢的驱动作用。【方法】通过气相色谱-质谱联用技术对比检测肚里黄和瓦蓝两种青稞原料酿造青稞酒过程中风味物质变化情况;采用高通量扩增子测序及多元统计分析比较两种青稞酒醅中微生物群落结构特征;结合蒙特卡洛置换检验确定环境因素对微生物的影响;通过模拟发酵对以上研究结果进行验证。【结果】肚里黄青稞酒醅中酯类化合物的含量及其发酵后期乳酸杆菌相对丰度和氨基酸含量显著低于瓦蓝酒醅(P<0.05);通过生物信息学分析发现,环境因素中游离氨基酸是青稞酒发酵过程微生物群落演替重要的推动因素,且乳酸杆菌相对丰度与游离氨基酸呈显著相关;模拟发酵实验证实了特定氨基酸不足会影响乳酸杆菌生长。【结论】揭示了青稞酒发酵过程中游离氨基酸对微生物群落组装的驱动作用,进而影响青稞酒的风味品质,为青稞酒的可控发酵提供理论基础。  相似文献   

19.
张海涵  唐明  陈辉  杜小刚  郑华 《生态学报》2007,27(12):5463-5470
利用BIOLOG代谢指纹方法分析了陕南商南和陕北安塞不同生态条件下油松菌根根际土壤微生物群落。结果表明,安塞油松和商南油松菌根根际微生物对糖类和氨基酸类碳源较易利用,商南油松菌根根际微生物总体上代谢碳源的种类和活性远大于安塞油松,而且对同类碳源的代谢商南油松的AWCD比安塞油松均高出2倍多。安塞油松菌根根际微生物以氨基酸类代谢群为优势类群,商南油松以糖类代谢群为优势类群。微生物群落多样性指数和微生物群落主成分分析(PCA)指标均表明商南油松和安塞油松菌根根际土壤微生物群落有明显不同,起分异作用的碳源主要为糖类,其次是羧酸类和氨基酸类。商南油松菌根根际土壤微生物群落AWCD极显著高于安塞油松(P〈0.01),细菌数量显著高于安塞油松(P〈0.05),Shannon指数和丰富度指数达极显著性差异(P〈0.01),商南油松和安塞油松菌根侵染率差异不显著,但菌根生物量差异达极显著水平(P〈0.01)。相关性分析表明,菌根生物量与丰富度指数、AWCD呈极显著正相关,与Shannon指数呈显著正相关,但是与菌根侵染率相关性不显著。在商南温暖潮湿丘陵区油松菌根根际微生物活性、群落大小和多样性高于安塞油松,在安塞黄土高原干旱区微生物群落稳定性强于商南油松。  相似文献   

20.
During crude oil extraction, the reduction in temperature and pressure results in the precipitation of paraffin wax that contains 20–40 carbon chain hydrocarbons. The paraffin wax may accumulate inside production tubes, pipelines, and processing facilities, and also in tankers during petroleum transportation. There are few bacterial strains that are able to degrade solid substrates. In the present study, the biodegradation of paraffin is evaluated using Rhodococcus erythropolis cells. This bacterium is able to grow using paraffin wax from an oil refinery plant as the sole carbon source. The cells grow as a thick biofilm over the solid substrate, make scale‐like structures that increase the area of the initially smooth surface of paraffin, produce biosurfactants, and become more negatively charged than ethanol‐ or glucose‐grown cells. When paraffin wax is supplied as microparticles, to increase the cell–substrate contact area and to simulate paraffin precipitation, the cells also adjust the composition of the fatty acids of the phospholipids of the cellular membrane to decrease its fluidity and paraffin biodegradation increases considerably. The study suggests that the phenotypic adaptation of R. erythropolis cells may be used to degrade paraffin wax under real conditions.  相似文献   

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