Neuenschwander Stefan M, Pernthaler Jakob, Posch Thomas, Salcher Michaela M
Limnological Station, Institute of Plant Biology, University of Zurich, Kilchberg, Switzerland.
Environ Microbiol. 2015 Mar;17(3):781-95. doi: 10.1111/1462-2920.12520. Epub 2014 Jun 30.
We studied the seasonal growth potential of opportunistic bacterial populations in Lake Zurich (Switzerland) by a series of grazer-free dilution culture assays. Pronounced shifts in the composition of the bacterial assemblages were observed within one doubling of total cell numbers, from initially abundant Actinobacteria to other fast-growing microbial lineages. Small populations with growth potentials far above community average were detected throughout the year with striking seasonal differences in their respective taxonomic affiliations. Members of Cytophaga-Flavobacteria (CF) were disproportionally proliferating only during phytoplankton blooms in spring and summer, while Beta- and Gammaproteobacteria showed superior growth at all other occasions. Growth rates of Alphaproteobacteria and esp. Sphingomonadaceae were significantly correlated to water temperatures and were far above community average in summer. Within the genus Flavobacterium, two species-like populations showed a tendency for fast growth in most experiments, while four others were exclusively proliferating either during a spring or during a summer phytoplankton bloom. Their high growth potentials but low in situ abundances hint at a tight control by bacterivorous grazers and at a consequently accelerated carbon flux to higher trophic levels.
我们通过一系列无食草动物的稀释培养试验，研究了瑞士苏黎世湖机会性细菌种群的季节性生长潜力。在总细胞数翻倍的过程中，观察到细菌群落组成发生了显著变化，从最初占优势的放线菌转变为其他快速生长的微生物谱系。全年都检测到了生长潜力远高于群落平均水平的小种群，其各自的分类归属存在显著的季节性差异。噬纤维菌-黄杆菌（CF）成员仅在春季和夏季浮游植物大量繁殖期间过度增殖，而β-和γ-变形菌在其他所有情况下都表现出更好的生长。α-变形菌尤其是鞘脂单胞菌科的生长速率与水温显著相关，且在夏季远高于群落平均水平。在黄杆菌属中，两个类似物种的种群在大多数实验中表现出快速生长的趋势，而另外四个种群仅在春季或夏季浮游植物大量繁殖期间增殖。它们的高生长潜力但原位丰度较低，这表明食细菌食草动物对其进行了严格控制，从而加速了碳向更高营养级的通量。
