The role of marine fungi in the microbial loop

海洋食物网在很大程度上是由固碳、初级生产和有机物再矿化的相互作用推动的。这些有机物质化学成分多样，以溶解、吸附或聚集的形式存在。它们被广泛的异养微生物降解。细菌在这一过程中的作用是相对较好的。它们以互补的分解策略形成代谢亚群，产生所谓的代谢行会。虽然海洋真菌普遍存在于海洋微生物群落中，但它们在微生物环路中的作用在很大程度上仍不清楚。微生物环中真菌是否与细菌相互作用以及如何与细菌相互作用影响着海洋碳转化的效率，因此具有很高的科学价值。在这里，我们假设(1)真菌和细菌根据可用的有机碳源形成特定的代谢公会，(2)从而通过跨王国相互作用增加公会的降解潜力。这是通过时间序列体外实验来研究的。为此，将在地理上不同的浮游植物水华事件期间对海水进行采样，并将其浓缩为真菌和细菌的微生物接种剂。该接种物将被用来接种不同的溶解有机底物，代表浮游植物的分泌物，以建立特定的代谢协会。然后，通过标签测序和LC-MS和核磁共振对其降解产物进行化学分析，对这些行业协会进行系统发育分析。

Marine food webs are largely driven by the interplay of carbon fixation, primary production, and remineralization of organic matter. These organic substances are chemically diverse and occur in dissolved, adsorbed or aggregated forms. They are degraded by a wide range of heterotrophic microorganisms. The role of bacteria in this process is comparatively well understood. They form metabolic subpopulations with complementary decomposition strategies, resulting in so-called metabolic guilds. Although marine fungi are ubiquitously present in pelagic microbial communities, their role in the microbial loop is still largely unknown. Whether and how fungi interact with bacteria in the microbial loop influences the efficiency of marine carbon transformation and is thus of high scientific value. Here we hypothesize that (1) fungi and bacteria form specific metabolic guilds depending on the available organic carbon source, and (2) thus increase the degradation potential of the guild via interkingdom interactions. This is investigated with time series in-vitro experiments. For this purpose, seawater will be sampled during geographically different phytoplankton bloom events and concentrated to a microbial inoculum of fungi and bacteria. The inoculum will be used to inoculate different dissolved organic substrates, representative of phytoplankton exudates, to establish specific metabolic guilds. These guilds will then be studied for phylogenetic analysis by tag-sequencing and chemical analyses by LC-MS and NMR of their degradation products.