Attermeyer Katrin, Tittel Jörg, Allgaier Martin, Frindte Katharina, Wurzbacher Christian, Hilt Sabine, Kamjunke Norbert, Grossart Hans-Peter
Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) Berlin, Experimental Limnology, Alte Fischerhütte 2, 16775, Stechlin, Germany,
Microb Ecol. 2015 Feb;69(2):361-71. doi: 10.1007/s00248-014-0549-4. Epub 2014 Dec 17.
The fate of allochthonous dissolved organic carbon (DOC) in aquatic systems is primarily controlled by the turnover of heterotrophic bacteria. However, the roles that abiotic and biotic factors such as light and DOC release by aquatic primary producers play in the microbial decomposition of allochthonous DOC is not well understood. We therefore tested if light and autochthonous DOC additions would increase allochthonous DOC decomposition rates and change bacterial growth efficiencies and community composition (BCC). We established continuous growth cultures with different inocula of natural bacterial communities and alder leaf leachates (DOCleaf) with and without light exposure before amendment. Furthermore, we incubated DOCleaf together with autochthonous DOC from lysed phytoplankton cultures (DOCphyto). Our results revealed that pretreatments of DOCleaf with light resulted in a doubling of bacterial growth efficiency (BGE), whereas additions of DOCphyto or combined additions of DOCphyto and light had no effect on BGE. The change in BGE was not accompanied by shifts in the phylogenetic structure of the BCC, but BCC was influenced by the DOC source. Our results highlight that a doubling of BGE is not necessarily accompanied by a shift in BCC and that BCC is more strongly affected by resource properties.
水生系统中异源溶解有机碳（DOC）的归宿主要受异养细菌周转的控制。然而，诸如光照和水生初级生产者释放的DOC等非生物和生物因素在异源DOC微生物分解中所起的作用尚未得到充分了解。因此，我们测试了添加光照和自源DOC是否会提高异源DOC的分解速率，并改变细菌生长效率和群落组成（BCC）。我们建立了连续生长培养体系，使用不同接种量的天然细菌群落和桤木叶浸出液（DOCleaf），在添加前分别进行有光照和无光照处理。此外，我们将DOCleaf与来自裂解浮游植物培养物的自源DOC（DOCphyto）一起孵育。我们的结果表明，光照预处理DOCleaf会使细菌生长效率（BGE）提高一倍，而添加DOCphyto或同时添加DOCphyto和光照对BGE没有影响。BGE的变化并未伴随着BCC系统发育结构的改变，但BCC受DOC来源的影响。我们的结果突出表明，BGE提高一倍不一定伴随着BCC的改变，并且BCC受资源属性的影响更大。
