Glaser Karin, Albrecht Martin, Baumann Karen, Overmann Jörg, Sikorski Johannes
Applied Ecology and Phycology, Institute for Biological Sciences, University of Rostock, Rostock, Germany.
Department of Soil Science, Faculty of Agricultural and Environmental Science, University of Rostock, Rostock, Germany.
Front Microbiol. 2022 Mar 16;13:769767. doi: 10.3389/fmicb.2022.769767. eCollection 2022.
Biological soil crusts (biocrusts) harbor a diverse community of various microorganisms with microalgae as primary producers and bacteria living in close association. In mesic regions, biocrusts emerge rapidly on disturbed surface soil in forest, typically after clear-cut or windfall. It is unclear whether the bacterial community in biocrusts is similar to the community of the surrounding soil or if biocrust formation promotes a specific bacterial community. Also, many of the interactions between bacteria and algae in biocrusts are largely unknown. Through high-throughput-sequencing analysis of the bacterial community composition, correlated drivers, and the interpretation of biological interactions in a biocrust of a forest ecosystem, we show that the bacterial community in the biocrust represents a subset of the community of the neighboring soil. Bacterial families connected with degradation of large carbon molecules, like cellulose and chitin, and the bacterivore were more abundant in the biocrust compared to bulk soil. This points to a closer interaction and nutrient recycling in the biocrust compared to bulk soil. Furthermore, the bacterial richness was positively correlated with the content of mucilage producing algae. The bacteria likely profit from the mucilage sheaths of the algae, either as a carbon source or protectant from grazing or desiccation. Comparative sequence analyses revealed pronounced differences between the biocrust bacterial microbiome. It seems that the bacterial community of the biocrust is recruited from the local soil, resulting in specific bacterial communities in different geographic regions.
生物土壤结皮（生物结皮）中栖息着各种各样的微生物群落，其中微藻作为初级生产者，与细菌紧密共生。在中生地区，生物结皮通常在森林中受干扰的表层土壤上迅速形成，特别是在皆伐或风倒之后。目前尚不清楚生物结皮中的细菌群落是否与周围土壤的群落相似，或者生物结皮的形成是否促进了特定的细菌群落。此外，生物结皮中细菌与藻类之间的许多相互作用在很大程度上还不为人知。通过对森林生态系统生物结皮中细菌群落组成、相关驱动因素以及生物相互作用的高通量测序分析，我们发现生物结皮中的细菌群落是邻近土壤群落的一个子集。与纤维素和几丁质等大分子碳降解相关的细菌科以及食细菌动物在生物结皮中比在大块土壤中更为丰富。这表明与大块土壤相比，生物结皮中存在更紧密的相互作用和养分循环。此外，细菌丰富度与产生黏液的藻类含量呈正相关。细菌可能从藻类的黏液鞘中获取益处，要么作为碳源，要么作为防止被啃食或干燥的保护剂。比较序列分析揭示了生物结皮细菌微生物组之间的显著差异。生物结皮的细菌群落似乎是从当地土壤中招募而来的，这导致了不同地理区域存在特定的细菌群落。
