The soil surface of drylands can typically be colonized by cyanobacteria and other microbes, forming biological soil crusts or ‘biocrusts’. Biocrusts provide critical benefits to ecosystems and are a common component of the largely arid and semi-arid Australian continent. Yet, their distribution and the parameters that shape their microbial composition have not been investigated. We present here the first detailed description of Australia's biocrust microbiome assessed from 15 sites across the continent using 16S rRNA sequencing. The most abundant bacterial phyla from all sites were Cyanobacteria, Proteobacteria, Actinobacteria, Chloroflexi and Bacteroidetes. Cyanobacterial communities from northern regions were more diverse and unclassified cyanobacteria were a noticeable feature of northern biocrusts. Segregation between northern and southern regions was largely due to the differential abundance of Microcoleus spp., with M. paludosus dominating in the north and M. vaginatus dominating in the south. The geographical shifts in bacterial composition and diversity were correlated to seasonal temperatures and summer rainfall. Our findings provide an initial reference for sampling strategies to maximize access to bacterial genetic diversity. As hubs for essential ecosystem services, further investigation into biocrusts in arid and semi-arid regions may yield discoveries of genetic mechanisms that combat increases in warming due to climate change.

中文翻译：

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气候决定了澳大利亚生物土壤结皮（生物结皮）中的微生物群落组成和多样性

旱地的土壤表面通常会被蓝藻和其他微生物定殖，形成生物土壤结皮或“生物结皮”。生物结壳为生态系统提供了重要的好处，并且是大部分干旱和半干旱澳大利亚大陆的常见组成部分。然而，尚未研究它们的分布和影响其微生物组成的参数。我们在这里首次详细描述了使用 16S rRNA 测序从整个大陆的 15 个地点评估的澳大利亚生物结壳微生物组。来自所有地点的最丰富的细菌门是蓝藻门、变形杆菌门、放线菌门、Chloroflexi 和拟杆菌门。来自北部地区的蓝藻群落更加多样化，未分类的蓝藻是北部生物结壳的一个显着特征。Microcoleus spp.，与M。paludosus在北部占主导地位，而M . 阴道在南方占主导地位。细菌组成和多样性的地理变化与季节性温度和夏季降雨相关。我们的研究结果为采样策略提供了初步参考，以最大限度地获取细菌遗传多样性。作为基本生态系统服务的枢纽，对干旱和半干旱地区生物结壳的进一步调查可能会发现对抗气候变化引起的变暖加剧的遗传机制。