Mutualistic interactions within microbial assemblages provide a survival strategy under extreme conditions; however, little is known about the complexity of interaction networks in multipartite, free-living communities. In the present study, the interplay within algae-dominated microbial communities exposed to harsh environmental influences in the Austrian Alps was assessed in order to reveal the interconnectivity of eukaryotic and prokaryotic inhabitants. All analyzed snowfields harbored distinct microbial communities. Network analyses revealed that mutual exclusion prevailed among microalgae in the alpine environment, while bacteria were mainly positively embedded in the interaction networks. Especially members of Proteobacteria, with a high prevalence of Oxalobacteraceae, Pseudomonadaceae, and Sphingomonadaceae showed genus-specific co-occurrences with distinct microalgae. Co-cultivation experiments with algal and bacterial isolates confirmed beneficial interactions that were predicted based on the bioinformatic analyses; they resulted in up to 2.6-fold more biomass for the industrially relevant microalga Chlorella vulgaris, and up to 4.6-fold increase in biomass for the cryophilic Chloromonas typhlos. Our findings support the initial hypothesis that microbial communities exposed to adverse environmental conditions in alpine systems harbor inter-kingdom supportive capacities. The insights into mutualistic inter-kingdom interactions and the ecology of microalgae within complex microbial communities provide explanations for the prevalence and resilience of such assemblages in alpine environments.

中文翻译：

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高山雪藻的微生物组显示出特定的界际连通性和具有支持能力的藻类-细菌相互作用。

微生物组合内的相互作用提供了极端条件下的生存策略；然而，人们对多方、自由生活社区中交互网络的复杂性知之甚少。在本研究中，评估了暴露于奥地利阿尔卑斯山恶劣环境影响的以藻类为主的微生物群落之间的相互作用，以揭示真核生物和原核生物居民的相互联系。所有分析的雪地都含有不同的微生物群落。网络分析表明，高寒环境中微藻之间普遍存在互斥，而细菌主要正嵌入相互作用网络中。特别是变形菌的成员，草酸杆菌科、假单胞菌科、和鞘氨醇单胞菌科与不同的微藻类表现出属特异性的共生。藻类和细菌分离物的共培养实验证实了基于生物信息学分析预测的有益相互作用；它们使工业相关的微藻小球藻的生物量增加了 2.6 倍，而低温的伤寒氯单胞菌的生物量增加了 4.6 倍。我们的研究结果支持最初的假设，即高山系统中暴露于不利环境条件的微生物群落具有跨界支持能力。对复杂微生物群落中的互惠互利的王国间相互作用和微藻生态学的见解为这种组合在高山环境中的普遍性和恢复力提供了解释。藻类和细菌分离物的共培养实验证实了基于生物信息学分析预测的有益相互作用；它们使工业相关的微藻小球藻的生物量增加了 2.6 倍，而低温的伤寒氯单胞菌的生物量增加了 4.6 倍。我们的研究结果支持最初的假设，即高山系统中暴露于不利环境条件的微生物群落具有跨界支持能力。对复杂微生物群落中的互惠互利的王国间相互作用和微藻生态学的见解为这种组合在高山环境中的普遍性和恢复力提供了解释。藻类和细菌分离物的共培养实验证实了基于生物信息学分析预测的有益相互作用；它们使工业相关的微藻小球藻的生物量增加了 2.6 倍，而低温的伤寒氯单胞菌的生物量增加了 4.6 倍。我们的研究结果支持最初的假设，即高山系统中暴露于不利环境条件的微生物群落具有跨界支持能力。对复杂微生物群落中的互惠互利的王国间相互作用和微藻生态学的见解为这种组合在高山环境中的普遍性和恢复力提供了解释。