为研究太湖蓝藻在越冬与复苏时期群落结构的时空变化规律,于2008年11月,2009年2月,2009年4月,在太湖富营养化较严重的湖区选取8个采样点(梅梁湾、竺山湾、贡湖湾、大浦、西太湖、南太湖、湖心和湖湾交汇处),分3层采水样,过滤并提取样品...为研究太湖蓝藻在越冬与复苏时期群落结构的时空变化规律,于2008年11月,2009年2月,2009年4月,在太湖富营养化较严重的湖区选取8个采样点(梅梁湾、竺山湾、贡湖湾、大浦、西太湖、南太湖、湖心和湖湾交汇处),分3层采水样,过滤并提取样品DNA经PCR扩增蓝藻16S rDNA序列,采用T-RFLP(末端标记的限制性酶切片段长度多样性)技术分析蓝藻群落结构和多样性变化。共得到87个不同的T-RFs(末端限制性酶切片段),表明太湖蓝藻具有丰富的基因多样性。T-RF相对丰度和聚类分析结果表明,太湖蓝藻群落结构在垂直空间上相似性较高,相似度>50%;在水平空间,与Microcystis spp.对应的信号峰在8个采样点均为最强峰(相对丰度为17.7%-47.5%)。竺山湾蓝藻多样性最低,西太湖最高,但其余采样点间蓝藻群落和Shannon多样性指数没有显著差异(P>0.05)。Microcystis相对丰度与Shannon多样性指数呈显著负相关(皮尔逊相关系数为-0.958)。在时间尺度上,相似性分析(Analysis of similarity,ANOSIM)结果显示太湖蓝藻群落结构存在极显著差异(P<0.01)。春季复苏时蓝藻多样性最高,秋季衰亡时最低。聚类分析表明样品聚成两大特征类群,秋季衰亡时样品独自聚为1支,而春季复苏期和冬季越冬期样品彼此混杂。展开更多
An annual investigation on phytoplankton communities was conducted to reveal the effects of nutrients on phytoplankton assemblages in Lake Taihu,East China. A total of 78 phytoplankton taxa were identified. Phytoplank...An annual investigation on phytoplankton communities was conducted to reveal the effects of nutrients on phytoplankton assemblages in Lake Taihu,East China. A total of 78 phytoplankton taxa were identified. Phytoplankton biomass was higher in the northern part of the lake than in the southern part. Cyanobacteria and Bacillariophyta alternated dominance in the northern area,where algal blooms often appear,and co-dominated in the southern area. In the northern part,the proportions of cyanobacteria and Bacillariophyta varied significantly in total biovolume,both along the phosphorus(P) gradient,and between total nitrogen levels(≤3 mg/L and >3 mg/L TN). The proportions of cyanobacteria and Bacillariophyta had no signif icant variations in total biovolume along P and N(nitrogen) gradients in the southern part. Correlation analysis and CCA results revealed that P was the key factor regulating phytoplankton community structure. Nitrogen was also important for the phytoplankton distribution pattern. It was concluded that nutrient structure was heterogeneous in space and shaped the distribution pattern of phytoplankton in the lake. Both exogenous P and internally sourced Prelease needs to be considered. N reduction should be considered simultaneously with P control to efficiently reduce eutrophication and algal blooms.展开更多
In this study, the 454 pyrosequencing technology was used to analyze the DNA of the Microcystis aeruginosa symbiosis system from cyanobacterial algal blooms in Taihu Lake, China. We generated 183 228 reads with an ave...In this study, the 454 pyrosequencing technology was used to analyze the DNA of the Microcystis aeruginosa symbiosis system from cyanobacterial algal blooms in Taihu Lake, China. We generated 183 228 reads with an average length of 248 bp. Running the 454 assembly algorithm over our sequences yielded 22 239 significant contigs. After excluding the M. aeruginosa sequences, we obtained 1 322 assembled contigs longer than 1 000 bp. Taxonomic analysis indicated that four kingdoms were represented in the community: Archaea (n = 9; 0.01%), Bacteria (n = 98 921; 99.6%), Eukaryota (n = 373; 3.7%), and Viruses (n = 18; 0.02%). The bacterial sequences were predominantly Alphaproteobacteria (n = 41 805; 83.3%), Betaproteobacteria (n = 5 254; 10.5%) and Gammaproteobacteria (n = 1 180; 2.4%). Gene annotations and assignment of COG (clusters of orthologous groups) functional categories indicate that a large number of the predicted genes are involved in metabolic, genetic, and environmental information processes. Our results demonstrate the extraordinary diversity of a microbial community in an ectosymbiotic system and further establish the tremendous utility of pyrosequencing.展开更多
Silver carp is one of the most important planktivorous fish in Chinese aquaculture and plays a significant role controlling cyanobacterial blooms. A balanced gut microbiota is crucial for growth and health of the host...Silver carp is one of the most important planktivorous fish in Chinese aquaculture and plays a significant role controlling cyanobacterial blooms. A balanced gut microbiota is crucial for growth and health of the host because of its important roles in immune defense, digestion of complex carbohydrates, and production of enterocytes. In our study, the dominant bacterial and cellulolytic bacterial （Clostridium 1, Clostridium 111, Clostridium XIVab, and Fibrobacter） communities in the contents and mucus of the silver carp gut （foregut, midgut, and hindgut） were analyzed by denaturing gradient gel electrophoresis and quantitative polymerase chain reaction （qPCR） analyses. The results revealed that the dominant and cellulolytic bacterial communities were significantly different among gut regions as well as in contents and mucus. Bacterial diversity and richness in contents and mucus increased along the gut and were higher in contents than those in local mucus. A sequence analysis of gut samples exhibited the conservative phylotypes of Proteobacteria, Actinobacteria, and Firmicutes. The gut of silver carp harbored an abundance of cellulolytic bacteria, particularly Clostridium XIVab. The foregut segment had the highest proportions of the four cellulolytic bacteria, followed by the midgut and hindgut. However, the proportions of cellulolytic species in the silver carp gut was much lower than those in the terrestrial vertebrate gastrointestinal tract. We conclude that gut bacteria could help silver carp obtain energy from cyanobacteria, which may be why silver carp can maintain high growth rates during cyanobacterial blooms.展开更多
文摘为研究太湖蓝藻在越冬与复苏时期群落结构的时空变化规律,于2008年11月,2009年2月,2009年4月,在太湖富营养化较严重的湖区选取8个采样点(梅梁湾、竺山湾、贡湖湾、大浦、西太湖、南太湖、湖心和湖湾交汇处),分3层采水样,过滤并提取样品DNA经PCR扩增蓝藻16S rDNA序列,采用T-RFLP(末端标记的限制性酶切片段长度多样性)技术分析蓝藻群落结构和多样性变化。共得到87个不同的T-RFs(末端限制性酶切片段),表明太湖蓝藻具有丰富的基因多样性。T-RF相对丰度和聚类分析结果表明,太湖蓝藻群落结构在垂直空间上相似性较高,相似度>50%;在水平空间,与Microcystis spp.对应的信号峰在8个采样点均为最强峰(相对丰度为17.7%-47.5%)。竺山湾蓝藻多样性最低,西太湖最高,但其余采样点间蓝藻群落和Shannon多样性指数没有显著差异(P>0.05)。Microcystis相对丰度与Shannon多样性指数呈显著负相关(皮尔逊相关系数为-0.958)。在时间尺度上,相似性分析(Analysis of similarity,ANOSIM)结果显示太湖蓝藻群落结构存在极显著差异(P<0.01)。春季复苏时蓝藻多样性最高,秋季衰亡时最低。聚类分析表明样品聚成两大特征类群,秋季衰亡时样品独自聚为1支,而春季复苏期和冬季越冬期样品彼此混杂。
基金Supported by the National Natural Science Foundation of China(No.31123001)the National Basic Research Program of China(973 Program)(No.2008CB418000)
文摘An annual investigation on phytoplankton communities was conducted to reveal the effects of nutrients on phytoplankton assemblages in Lake Taihu,East China. A total of 78 phytoplankton taxa were identified. Phytoplankton biomass was higher in the northern part of the lake than in the southern part. Cyanobacteria and Bacillariophyta alternated dominance in the northern area,where algal blooms often appear,and co-dominated in the southern area. In the northern part,the proportions of cyanobacteria and Bacillariophyta varied significantly in total biovolume,both along the phosphorus(P) gradient,and between total nitrogen levels(≤3 mg/L and >3 mg/L TN). The proportions of cyanobacteria and Bacillariophyta had no signif icant variations in total biovolume along P and N(nitrogen) gradients in the southern part. Correlation analysis and CCA results revealed that P was the key factor regulating phytoplankton community structure. Nitrogen was also important for the phytoplankton distribution pattern. It was concluded that nutrient structure was heterogeneous in space and shaped the distribution pattern of phytoplankton in the lake. Both exogenous P and internally sourced Prelease needs to be considered. N reduction should be considered simultaneously with P control to efficiently reduce eutrophication and algal blooms.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No. KSCX2-YW-G-073)
文摘In this study, the 454 pyrosequencing technology was used to analyze the DNA of the Microcystis aeruginosa symbiosis system from cyanobacterial algal blooms in Taihu Lake, China. We generated 183 228 reads with an average length of 248 bp. Running the 454 assembly algorithm over our sequences yielded 22 239 significant contigs. After excluding the M. aeruginosa sequences, we obtained 1 322 assembled contigs longer than 1 000 bp. Taxonomic analysis indicated that four kingdoms were represented in the community: Archaea (n = 9; 0.01%), Bacteria (n = 98 921; 99.6%), Eukaryota (n = 373; 3.7%), and Viruses (n = 18; 0.02%). The bacterial sequences were predominantly Alphaproteobacteria (n = 41 805; 83.3%), Betaproteobacteria (n = 5 254; 10.5%) and Gammaproteobacteria (n = 1 180; 2.4%). Gene annotations and assignment of COG (clusters of orthologous groups) functional categories indicate that a large number of the predicted genes are involved in metabolic, genetic, and environmental information processes. Our results demonstrate the extraordinary diversity of a microbial community in an ectosymbiotic system and further establish the tremendous utility of pyrosequencing.
基金Supported by the National Science and Technology Ministry(No.2014BAC09B02)the National Water Pollution Control and Management Technology Major Projects(No.2012ZX07101-002)
文摘Silver carp is one of the most important planktivorous fish in Chinese aquaculture and plays a significant role controlling cyanobacterial blooms. A balanced gut microbiota is crucial for growth and health of the host because of its important roles in immune defense, digestion of complex carbohydrates, and production of enterocytes. In our study, the dominant bacterial and cellulolytic bacterial （Clostridium 1, Clostridium 111, Clostridium XIVab, and Fibrobacter） communities in the contents and mucus of the silver carp gut （foregut, midgut, and hindgut） were analyzed by denaturing gradient gel electrophoresis and quantitative polymerase chain reaction （qPCR） analyses. The results revealed that the dominant and cellulolytic bacterial communities were significantly different among gut regions as well as in contents and mucus. Bacterial diversity and richness in contents and mucus increased along the gut and were higher in contents than those in local mucus. A sequence analysis of gut samples exhibited the conservative phylotypes of Proteobacteria, Actinobacteria, and Firmicutes. The gut of silver carp harbored an abundance of cellulolytic bacteria, particularly Clostridium XIVab. The foregut segment had the highest proportions of the four cellulolytic bacteria, followed by the midgut and hindgut. However, the proportions of cellulolytic species in the silver carp gut was much lower than those in the terrestrial vertebrate gastrointestinal tract. We conclude that gut bacteria could help silver carp obtain energy from cyanobacteria, which may be why silver carp can maintain high growth rates during cyanobacterial blooms.
