Data from: Photoautotrophic symbiont and geography are major factors affecting highly structured and diverse bacterial communities in the lichen microbiome

Although common knowledge dictates that the lichen thallus is formed solely by a fungus (mycobiont) that develops a symbiotic relationship with an alga and/or cyanobacterium (photobiont), the non-photoautotrophic bacteria found in lichen microbiomes are increasingly regarded as integral components of lichen thalli. For this study, comparative analyses were conducted on lichen-associated bacterial communities to test for effects of photobiont-types (i.e., green algal vs. cyanobacterial), mycobiont-types, and large-scale spatial distances (from tropical to arctic latitudes). Amplicons of the 16S (SSU) rRNA gene were examined using both Sanger sequencing of cloned fragments and barcoded pyrosequencing. Rhizobiales is typically the most abundant and taxonomically diverse order in lichen microbiomes; however, overall bacterial diversity in lichens is shown to be much higher than previously reported. Members of Acidobacteriaceae, Acetobacteraceae, Brucellaceae, and sequence group LAR1 are the most commonly found groups across the phylogenetically and geographically broad array of lichens examined here. Major bacterial community trends are significantly correlated with differences in large-scale geography, photobiont-type, and mycobiont-type. The lichen as a microcosm represents a structured, unique microbial habitat with greater ecological complexity and bacterial diversity than previously appreciated and can serve as a model system for studying larger ecological and evolutionary principles.

尽管学界普遍认知认为，地衣体（lichen thallus）仅由与藻类和/或蓝细菌（cyanobacterium）形成共生关系的真菌共生体（mycobiont）构成，但在地衣微生物组（lichen microbiomes）中发现的非光自养细菌（non-photoautotrophic bacteria）正日益被视为地衣体不可或缺的组成部分。
本研究对地衣相关细菌群落开展比较分析，以探究光合共生体类型（photobiont-type，即绿藻与蓝细菌两类）、真菌共生体类型以及大尺度空间距离（从热带至北极纬度）的影响效应。
本研究通过克隆片段桑格测序（Sanger sequencing）与带条形码焦磷酸测序（barcoded pyrosequencing）两种方法，对16S（SSU）rRNA基因（16S (SSU) rRNA gene）的扩增子进行了检测。
根瘤菌目（Rhizobiales）通常是地衣微生物组中丰度最高、分类学多样性最丰富的类群；然而研究显示，地衣中整体细菌多样性远高于此前的报道结果。
酸杆菌科（Acidobacteriaceae）、醋杆菌科（Acetobacteraceae）、布鲁氏菌科（Brucellaceae）以及序列类群LAR1的成员，是本次研究涵盖的系统发育与地理分布跨度极大的各类地衣中最常见的类群。
细菌群落的主要组成趋势与大尺度地理环境、光合共生体类型以及真菌共生体类型的差异显著相关。
地衣作为微型生态系统（microcosm），代表了一种结构化的独特微生物生境，其生态复杂性与细菌多样性均远超此前的认知，可作为研究更大尺度生态与进化原理的模式系统。