Effects of acute exposures of 2,4,6-trinitrotoluene and inorganic lead on the fecal microbiome of the green anole (Anolis carolinensis)

Microbiome studies focused on ecologically relevant vertebrate models like reptiles have been limited. Because of their relatively small home range, fast maturation, and high fecundity, lizards are an excellent reptilian terrestrial indicator species. For this study we used the green anole, Anolis carolinensis, to assess the impact of military relevant contaminants on fecal microbiome composition. Fourteen day sub-acute exposures were conducted via oral gavage with 2,4,6-Trinitrotoluene (TNT) and inorganic lead at doses of 60 mg/kg and 20 mg/kg of body weight, respectively. Body weights and food consumption were monitored and fecal samples were collected for high-throughput 16S rRNA gene amplicon sequencing and analytical chemistry at days 0 and 15. At the end of the study, liver and gut were harvested for body burden data. Chemical analysis confirmed accumulation of TNT, TNT transformation products, and lead in liver tissue and fecal samples. Bacterial community analysis of fecal material revealed significant differences between day 0 and day 15 of TNT exposed anoles with an operational taxonomic unit (OTU) within the genus Erwinia representing 32% of the microbial community in TNT exposed anoles. Predictable changes in gut microbiome composition could offer an easily assayed, noninvasive biomarker for specific chemical exposure providing enhanced scientific support to risk assessments on military installations.

以具有生态相关性的脊椎动物模型（如爬行动物）为对象的微生物组 (microbiome) 研究迄今仍较为有限。蜥蜴因其活动范围相对狭小、成熟速度快且繁殖力强，成为优质的爬行动物陆生指示物种。本研究以卡罗莱纳安乐蜥（Anolis carolinensis）为研究对象，旨在评估军事相关污染物对其粪便微生物组组成的影响。本研究通过经口灌胃方式，分别以60mg/kg体重、20mg/kg体重的剂量对受试个体开展为期14天的亚急性暴露实验，暴露物为2,4,6-三硝基甲苯（TNT）与无机铅。研究期间分别于第0天和第15天监测受试个体的体重与摄食量，并采集粪便样本用于高通量16S rRNA基因扩增子测序及化学分析；实验结束时采集肝脏与肠道组织以获取体内污染物负荷数据。化学分析结果证实，TNT、TNT转化产物及铅在肝脏组织与粪便样本中均发生蓄积。粪便样本的细菌群落分析显示，经TNT暴露的安乐蜥在第0天与第15天的群落结构存在显著差异；其中欧文氏菌属（Erwinia）下的一个操作分类单元（operational taxonomic unit，OTU）在TNT暴露组的微生物群落中占比达32%。肠道微生物组组成的可预测变化，可作为针对特定化学暴露的便捷检测型非侵入性生物标志物，为军事设施的风险评估提供更为坚实的科学支撑。