Xie Guijuan, Tang Xiangming, Gong Yi, Shao Keqiang, Gao Guang
Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, China.
University of Chinese Academy of Sciences, Beijing, China.
Front Microbiol. 2020 Dec 4;11:593589. doi: 10.3389/fmicb.2020.593589. eCollection 2020.
Particles are hotspots of bacterial growth and nutrient recycling in aquatic ecosystems. In the study of particle-attached (PA) and/or free-living (FL) microbial assemblages, the first step is to separate particles from their surrounding water columns. Widely used collection techniques are filtration using different pore size filters, and centrifugation; however, it is unclear how the bacterial diversity, bacterial community structure (BCS) and taxonomic composition of PA assemblages are affected by different particle collection methods. To address this knowledge gap, we collected planktonic particles from eutrophic Lake Taihu, mesotrophic Lake Tianmu, and oligotrophic Lake Fuxian in China, using filtration with five pore size of filters (20, 10, 8.0, 5.0, and 3.0 μm), and centrifugation. Bacterial communities were then analyzed using Illumina MiSeq sequencing of the 16S rRNA gene. We found that PA collection method affected BCS significantly in all lakes. Centrifugation yielded the highest species diversity and lowest mean percentage of photoautotrophic in Lake Taihu, but not in the other two lakes, thus highlighting the potential compatibility of this method in the study of PA assemblage in eutrophic lakes. The high bacterial diversity and low relative percentage of was in samples retained on 5.0 μm filters in all lakes. These results suggest that collecting PA samples in lakes using filters with 5.0 μm pore size is the preferred protocol, if species diversity and heterotrophic bacteria are the top research priorities, when comparing bacterial communities in different trophic lakes at the same time. The present study offers the possibility of collecting PA samples using unified methods in oligotrophic to eutrophic lakes.
在水生生态系统中，颗粒是细菌生长和养分循环的热点。在研究附着于颗粒（PA）和/或自由生活（FL）的微生物群落时，第一步是将颗粒与周围的水柱分离。广泛使用的收集技术是使用不同孔径过滤器进行过滤和离心；然而，尚不清楚不同的颗粒收集方法如何影响PA群落的细菌多样性、细菌群落结构（BCS）和分类组成。为了填补这一知识空白，我们在中国的富营养化太湖、中营养化天目湖和贫营养化抚仙湖采集了浮游颗粒，使用了五种孔径的过滤器（20、10、8.0、5.0和3.0μm）进行过滤以及离心。然后使用16S rRNA基因的Illumina MiSeq测序分析细菌群落。我们发现，PA收集方法在所有湖泊中均对BCS有显著影响。离心法在太湖产生了最高的物种多样性和最低的光合自养生物平均百分比，但在其他两个湖泊中并非如此，这突出了该方法在富营养化湖泊PA群落研究中的潜在适用性。在所有湖泊中，5.0μm过滤器截留的样品中细菌多样性高且相对百分比低。这些结果表明，如果将物种多样性和异养细菌作为首要研究重点，同时比较不同营养状态湖泊中的细菌群落时，使用孔径为5.0μm的过滤器收集湖泊中的PA样品是首选方案。本研究提供了在贫营养到富营养湖泊中使用统一方法收集PA样品的可能性。
