Contribution of large bacteria to bacterial biomass in a deep freshwater lake (Lake Biwa, Japan)
Contribution of large bacteria to bacterial biomass in a deep freshwater lake (Lake Biwa, Japan)
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DOI：
10.3354/ame01949
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发表时间：
2020-01-01
影响因子：
1.4
通讯作者：
Shimizu, Yoshihisa
中科院分区：
文献类型：
--
作者：
Shen, Shang;Shimizu, Yoshihisa
尽管细菌细胞体积在水生环境中的微生物生态学中的重要性，但关于细菌细胞体积的季节和空间变化的影响的文献仍然很少。我们用透射电子显微镜检查细菌细胞大小的季节和空间变化为18个月的2层（上层0.5米和下层60米）的日本琵琶湖，一个大而深的淡水湖。在分层期间，我们发现，细菌细胞体积在浅水层的范围为0.017至0.12 μ m（3）（中位数），而在浅水层的变化较小（0.016至0.033 μ m（3），中位数），远低于在浅水层。此外，在浅水层，细胞体积在分层期间大于在混合期间（高达5.7倍）。细胞体积的这些差异导致在浅水层和浅水层中的细菌生物量相当，尽管事实上，在浅水层中的细菌丰度比在浅水层中的低。我们还发现，较大的细菌，这是不太可能被吃过的异养nanoflagellates，在分层期间的浅水层的生物量增加。我们的数据表明，当细胞体积用作恒定参数值时，碳通量（例如细菌生产力）的估计需要谨慎解释。在深淡水湖中，细胞体积随季节和空间变化的差异可能在很大程度上影响估计。
Despite the importance of bacterial cell volume in microbial ecology in aquatic environments, literature regarding the effects of seasonal and spatial variations on bacterial cell volume remains scarce. We used transmission electron microscopy to examine seasonal and spatial variations in bacterial cell size for 18 mo in 2 layers (epilimnion 0.5 m and hypolimnion 60 m) of Lake Biwa, Japan, a large and deep freshwater lake. During the stratified period, we found that the bacterial cell volume in the hypolimnion ranged from 0.017 to 0.12 mu m(3) (median), whereas that in the epilimnion was less variable (0.016 to 0.033 mu m(3), median) and much lower than that in the hypolimnion. Additionally, in the hypolimnion, cell volume during the stratified period was greater than that during the mixing period (up to 5.7-fold). These differences in cell volume resulted in comparable bacterial biomass in the hypolimnion and epilimnion, despite the fact that there was lower bacterial abundance in the hypolimnion than in the epilimnion. We also found that the biomass of larger bacteria, which are not likely to be grazed by heterotrophic nanoflagellates, increased in the hypolimnion during the stratified period. Our data suggest that estimation of carbon flux (e.g. bacterial productivity) needs to be interpreted cautiously when cell volume is used as a constant parametric value. In deep freshwater lakes, a difference in cell volume with seasonal and spatial variation may largely affect estimations.