Ávila Marcelo P, Staehr Peter A, Barbosa Francisco A R, Chartone-Souza Edmar, Nascimento Andréa M A
Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brazil.
Department of Bioscience, Aarhus University, Frederiksborgvej 399, Box 358, 4000 Roskilde, Denmark.
FEMS Microbiol Ecol. 2017 Jan 1;93(1). doi: 10.1093/femsec/fiw218.
Bacteria are highly important for the cycling of organic and inorganic matter in freshwater environments; however, little is known about the diversity of bacterioplankton in tropical systems. Studies on carbon and nutrient cycling in tropical lakes suggest a very different seasonality from that of temperate climates. Here, we used 16S rRNA gene next-generation sequencing (NGS) to investigate seasonal changes in bacterioplankton communities of two tropical lakes, which differed in trophic status and mixing regime. Our findings revealed seasonally and depth-wise highly dynamic bacterioplankton communities. Differences in richness and structure appeared strongly related to the physicochemical characteristics of the water column, especially phosphate, pH and oxygen. Bacterioplankton communities were dominated by common taxonomic groups, such as Synechococcus and Actinobacteria acI, as well as rare and poorly characterized taxa such as 'Candidatus Methylacidiphilum' (Verrucomicrobia). Stratification and oxygen depletion during the rainy season promoted the occurrence of anoxygenic phototrophic and methanotrophic bacteria important for carbon and nutrient cycling. Differences in lake mixing regime were associated with seasonal beta diversity. Our study is the first attempt to use NGS for cataloging the diversity of bacterioplankton communities in Brazilian lakes and thus contributes to the ongoing worldwide endeavor to characterize freshwater lake bacterioplankton signatures.
细菌对于淡水环境中有机和无机物质的循环极为重要；然而，对于热带系统中浮游细菌的多样性却知之甚少。对热带湖泊碳和养分循环的研究表明，其季节性与温带气候截然不同。在此，我们利用16S rRNA基因下一代测序（NGS）技术，研究了两个营养状态和混合机制不同的热带湖泊浮游细菌群落的季节变化。我们的研究结果揭示了浮游细菌群落在季节和深度上具有高度动态性。丰富度和结构的差异似乎与水柱的理化特征密切相关，尤其是磷酸盐、pH值和氧气。浮游细菌群落主要由常见的分类群主导，如聚球藻属和放线菌acI，以及罕见且特征不明的类群，如“嗜酸甲基杆菌候选菌属”（疣微菌门）。雨季的分层和氧气消耗促进了对碳和养分循环至关重要的厌氧光合细菌和甲烷营养细菌的出现。湖泊混合机制的差异与季节性β多样性相关。我们的研究首次尝试利用NGS技术对巴西湖泊浮游细菌群落的多样性进行编目，从而为全球正在进行的表征淡水湖泊浮游细菌特征的努力做出贡献。
