Microbial Contributions to Arsenic Transformation in the Gut

摘要(项目3：Pawel Kiela、Paul Carini和Albert Barberán) 提取经济金属后留下的遗留尾矿经常与共生元素一起富集 对邻近社区和社区造成严重健康危害的污染物，如砷 生态系统。砷的摄入与糖尿病、多种癌症和心血管疾病有关。 精神错乱。砷毒性的作用方式尚不清楚；然而，毒性的程度与 As代谢物的价态和甲基化状态(例如，三价As物种iAsIII、MMAIII和DMAIII是两种 细胞毒性是iAsV的两倍；甲基化的五价砷的细胞毒性比ASV低10倍)。胆量 微生物群是AS在宿主中的主要接触点，因为口服是主要的接触 路线。此外，体外研究已经证明了人类结肠微生物区系的生物转化能力。 IAS既有更多的有毒形式，也有更少的毒性形式。因此，准确的风险评估需要了解 肠道微生物群对宿主的生物可及性和物种形成的体前贡献。这个 本提案的总体目标是：1)将老鼠内脏的组成与背景联系起来 微生物组具有代谢砷的功能和2)评估定义为- 改变微生物群落以影响体内糖尿病暴露后的结果。这个 多学科团队将采用一种独特的方法来确定组成之间的特定关联 肠道微生物组，其隔离和/或转化As的遗传和功能能力，以及其 作为对AS暴露的反应，加重或减轻宿主糖尿病结果。常规微生物分类学 (16S rRNA基因扩增子图谱)和功能基因(鸟枪式元基因组)分析将鉴定 宿主性别、年龄和砷暴露对小鼠粪便群落组成的影响。这项分子分析将 与相同粪便群落的基于功能的高通量培养分析相结合，以便于 设计了120个不同的合成微生物群落(Syncoms)。每个平台的功能容量 将确定转换/隔离IAS的Syncom，并可能捕获以下新特性 微生物介导的AS生物转化，在使用分离的系统类型的研究中可能会遗漏。这个 SynComs将聚集在具有不同能力的功能行会中，以增加或减少AS负载 由主人亲身体验。这些Syncoms将在无菌小鼠身上进行测试，以评估特定的 具有明显AS生物转化能力的微生物联合体，可调节AS暴露对糖尿病的影响。 据推测，降低AS毒性和相关糖尿病后果的微生物群落 作为潜在的益生菌被开发。这一假说将通过验证正向能力来检验。 结果Syncoms可定植无特定病原体(SPF)的小鼠宿主并预防或减少糖尿病前期 IAsIII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.