土著菌群与蚯蚓肠道菌群共享核心物种协同抵御灭蚁灵胁迫研究

Keystone Species of Soil Indigenous Flora and Earthworm Intestinal Flora Help to Resist Mirex Stress

采集实际场地中不同浓度梯度(0~27.7 mg/kg)灭蚁灵污染土壤,设置蚯蚓土培试验,采用高通量测序技术,分析蚯蚓肠道菌群和土著菌群的结构和功能;通过MetagenomeSeq分析、LEfSe(linear discriminant analysis effect size)分析和随机森林(random forests)分析以及网络分析,识别其核心类群。发现:灭蚁灵胁迫下蚯蚓肠道菌群相较土著菌群的结构、组成受到的扰动更显著(P<0.05);②不同浓度梯度灭蚁灵胁迫下,蚯蚓肠道菌群和土著菌群组合存在稳定的核心物种,主要为气单胞菌属(Aeromonas)、黄杆菌属(Flavobacterium)、盖勒氏菌属(Gallerella)、微枝形杆菌属(Microvirga)、地杆菌属(Pedobacter)、亨氏菌(Ramlibacter)、Zavarzinella;③这些核心种群在互作网络的平均度中心性、紧密中心性、特征向量中心性分别为136.72、0.44、0.52,均高于非核心种群的对应指标(91.52、0.42、0.33),表明核心种群具有更高的网络连通性,且此类核心种群具有碳氮转化和农药降解能力,说明蚯蚓肠道菌群和土著菌群可以通过共享核心物种与其他微生物联系紧密,具备发挥农药降解代谢的潜在功能,实现协同抵御土壤中灭蚁灵胁迫。

In this study,soils with different mirex concentrations(0–27mg/kg)were collected to set up earthworm inoculation trials.High-throughput sequencing was used to analyze the structure and function of earthworm intestinal and soil indigenous microbial communities.Meanwhile,the keystone microbial taxa were identified through network analysis.The results obtained here found that 1)The structure and composition of the earthworm intestinal bacteria varied more significantly than those of the soil indigenous bacteria(P<0.05);2)The keystone bacteria remained stable in the worm gut and the soil despite varying mirex concentration,which was mainly consisted of Aeromonas,Flavobacterium,Gallerella,Microvirga,Pedobacter,Ramlibacter,Zavarzinella;3)The keystone bacteria had higher network connectivity than the rest bacteria,whose mean degree centrality,closeness centrality,eigenvector centrality values were 136.7,0.44 and 0.52,respectively,clearly higher than those in the rest bacteria(91.52,0.42 and 0.33,respectively).In addition,the keystone bacteria were closely involved in the carbon/nitrogen transformation and pesticide degradation,which not only protect the keystone bacteria from mirex toxicity,but might also assist other bacteria in relieving pesticide toxicity.