Microbial Contributions to Arsenic Transformation in the Gut

摘要（项目3：Pawel Kiela、Paul卡里尼和Albert Barberán） 提取经济金属后留下的遗留尾矿经常富含共生金属， 对邻近社区造成严重健康危害的砷等污染物， 生态系统摄入砷与糖尿病、多种癌症和心血管疾病有关。 紊乱As毒性的作用方式尚不清楚;然而，毒性程度与 As代谢物的价态和甲基化状态（例如三价As物质，iAs III、MMAIII和DMAIII，是两种 细胞毒性比iAsV高10倍;甲基化五价砷的细胞毒性比AsV低10倍）。肠道 微生物组是宿主中As的主要接触点，因为口服摄入是主要暴露 路线此外，体外研究已经证明了人类结肠微生物群生物转化 对更多和更少毒性形式的免疫。因此，准确的风险评估需要了解 肠道微生物组对宿主As-负荷的生物可及性和物种形成的系统前贡献。的 该提议的总体目标是1）将小鼠肠道的组成置于背景中 微生物组及其代谢As的功能能力和2）评估定义As的能力- 转化微生物群落影响体内糖尿病的结果后，作为曝光。的 多学科团队将采用独特的方法来确定组成之间的具体关联 肠道微生物组，其隔离和/或转化As的遗传和功能能力， 无论是加重或减轻主机糖尿病的结果，以响应作为暴露。常规微生物分类 (16S rRNA基因扩增子分析）和功能基因（鸟枪宏基因组）分析将鉴定 宿主性别、年龄和砷暴露对小鼠粪便群落组成影响这种分子分析将 与相同粪便群落的基于功能的高通量培养分析相结合， 设计了120个不同的合成微生物群落（SynComs）。每个人的功能 将确定SynCom转换/隔离iA，并可能捕获 微生物介导的生物转化，可能会错过在研究中使用孤立的大肠杆菌类型。的 SynComs将聚集在功能性公会中，这些公会具有不同的能力来增加或减少As负载 主人的经历。这些SynComs将在无菌小鼠中进行测试，以评估特异性 微生物财团具有不同的生物转化能力，以调节糖尿病的结果作为曝光。 据推测，减少砷毒性和相关糖尿病结果的微生物群落可以被 被用作潜在的益生菌。这一假设将通过验证阳性- 结果SynComs定殖于无特定病原体（SPF）小鼠宿主并预防或减少糖尿病前病变 iAs III暴露的影响。

ABSTRACT (Project 3: Pawel Kiela, Paul Carini, and Albert Barberán) Legacy mine tailings that remain after extraction of economic metals are frequently enriched with co-occurring contaminants such as arsenic (As) that pose serious health hazards to neighboring communities and ecosystems. As-ingestion has been associated with diabetes, numerous cancers, and cardiovascular disorders. The mode of action for As toxicity is not clear; however, the degree of toxicity is associated with the valence and the methylation state of As metabolites (e.g. trivalent As species, iAsIII, MMAIII, and DMAIII ,are two times more cytotoxic than iAsV; methylated pentavalent arsenicals are 10-fold less cytotoxic than AsV). The gut microbiome is a primary point of contact for As in the host because oral ingestion is the principal exposure route. In addition, in vitro studies have demonstrated the capacity of human colon microbiota to biotransform iAs to both more and less toxic forms. Thus, accurate As risk assessment requires understanding of presystemic contributions by the gut microbiome to the bioaccessibility and speciation of the host As-load. The overall objectives of this proposal are to 1) contextualize the composition of the mouse gut microbiome with its functional capacity to metabolize As and to 2) evaluate the capacity of defined As- transforming microbial communities to affect in vivo diabetic outcomes following As exposure. The multidisciplinary team will employ a unique approach to identify specific associations between the composition of the gut microbiome, its genetic and functional capacity to sequester and/or transform As, and its capacity to either exacerbate or mitigate host diabetic outcomes in response to As exposure. Routine microbial taxonomic (16S rRNA gene amplicon profiling) and functional gene (shotgun metagenome) analyses will identify the impact of host sex, age and As-exposure on mouse fecal community composition. This molecular analysis will be combined with function-based high throughput culture analysis of the same fecal communities to facilitate the design of 120 distinct synthetic microbial communities (SynComs). The functional capacities of each SynCom to transform/sequester iAs will be identified and will potentially capture emergent properties of microbially-mediated As biotransformation that might be missed in studies using isolated phylotypes. The SynComs will be clustered in functional guilds with differing capacities to increase or decrease the As-load experienced by the host. These SynComs will be tested in germ-free mice to evaluate the capacity of specific microbial consortia with distinct As biotransformation capacities to modulate diabetic outcomes of As exposure. It is hypothesized that microbial communities that reduce As toxicity and associated diabetic outcomes can be exploited as potential probiotics. This hypothesis will be tested through verification of the ability of positive- outcome SynComs to colonize a specific pathogen free (SPF) mouse host and prevent or reduce pro-diabetic effects of iAsIII exposure.