Section for Microbiology, Department of Biology, Aarhus University, Ny Munkegade 114, 8000 Aarhus C, Denmark.
Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology (BIUST), Botswana.
FEMS Microbiol Ecol. 2022 Mar 9;98(2). doi: 10.1093/femsec/fiac015.
Host-symbiont interactions may form obligatory or facultative associations that are context dependent. Long-term studies on microbiome composition from wild populations should assess the temporal and spatial dynamics of host-microbe associations. We characterized the temporal and spatial variation in the bacterial microbiome composition in six populations of the social spider Stegodyphus dumicola for 2.5 years, using 16S rRNA gene amplicon sequencing of whole spiders. Individuals within a nest exhibit highly similar microbiomes, which remain stable over several generations and are not predictably affected by seasonal variation in temperature or humidity. This stability in nest microbiome is likely due to social transmission, whereas drift-like processes during new nest foundations explain variation in host microbiomes between nests. This is supported by the lack of obligate symbionts (i.e. no symbionts are present in all spider individuals). Quantitative PCR analyses showed that the bacterial load of individual spiders is stable in healthy nests but can increase dramatically in perishing nests. These increases are not driven by specific bacterial taxa but likely caused by loss of host immune control under deteriorating conditions. Spider nests show an annual survival rate of approximately 45%, but nest death is not correlated to microbiome composition, and the bacteria found in S. dumicola are not considered to be high virulence pathogens.
宿主-共生体相互作用可能形成依赖于环境的强制性或兼性共生关系。对野生种群微生物组组成的长期研究应评估宿主-微生物共生体的时空动态。我们使用整个蜘蛛的 16S rRNA 基因扩增子测序，对六种社会性蜘蛛 Stegodyphus dumicola 的细菌微生物组组成进行了 2.5 年的时间和空间变化特征分析。巢内个体具有高度相似的微生物组，这些微生物组在几代内保持稳定，不受温度或湿度季节性变化的可预测影响。这种巢内微生物组的稳定性可能是由于社会性传播所致，而在新巢建立过程中的漂移样过程则解释了巢间宿主微生物组的变化。这是因为缺乏强制性共生体（即没有共生体存在于所有蜘蛛个体中）。定量 PCR 分析表明，健康巢中个体蜘蛛的细菌负荷稳定，但在腐烂巢中会急剧增加。这些增加不是由特定的细菌类群驱动的，而可能是由于宿主免疫控制在恶化条件下丧失所致。蜘蛛巢每年的存活率约为 45%，但巢的死亡与微生物组组成无关，而且在 S. dumicola 中发现的细菌不被认为是高毒力病原体。
