Department of Microbiology, University of Dhaka, Dhaka, 1000, Bangladesh.
Institute of Tissue Banking and Biomaterial Research, Atomic Energy Research Establishment, Savar, Dhaka, 1349, Bangladesh.
BMC Microbiol. 2023 Aug 30;23(1):241. doi: 10.1186/s12866-023-02980-0.
Arsenic (As) and its species are major pollutants in ecological bodied including groundwater in Bangladesh rendering serious public health concern. Bacteria with arsenotrophic genes have been found in the aquifer, converting toxic arsenite [As (III)] to less toxic arsenate [As (V)] that is easily removed using chemical and biological trappers. In this study, genomic and metagenomic approaches parallel to culture-based assay (Graphical abstract) have made it possible to decipher phylogenetic diversity of groundwater arsenotrophic microbiomes along with elucidation of their genetic determinants.
Seventy-two isolates were retrieved from six As-contaminated (average As concentration of 0.23 mg/L) groundwater samples from Munshiganj and Chandpur districts of Bangladesh. Twenty-three isolates harbored arsenite efflux pump (arsB) gene with high abundance, and ten isolates possessing arsenite oxidase (aioA) gene, with a wide range of minimum inhibitory concentration, MIC (2 to 32 mM), confirming their role in arsenite metabolism. There was considerable heterogeneity in species richness and microbial community structure. Microbial taxa from Proteobacteria, Firmicutes and Acidobacteria dominated these diversities. Through these combinatorial approaches, we have identified potential candidates such as, Pseudomonas, Acinetobacter, Stenotrophomonas, Achromobacter, Paraburkholderia, Comamonas and Klebsiella and associated functional genes (arsB, acr3, arsD, arsH, arsR) that could significantly contribute to arsenite detoxification, accumulation, and immobilization.
Culture-dependent and -independent shotgun metagenomic investigation elucidated arsenotrophic microbiomes and their functions in As biogeochemical transformation. These findings laid a foundation for further large-scale researches on the arsenotrophic microbiomes and their concurrent functions in As biogeochemical transformation in As-contaminated areas of Bangladesh and beyond.
砷（As）及其化合物是包括孟加拉国地下水在内的生态系统中的主要污染物，引起了严重的公共健康关注。在含水层中发现了具有砷营养基因的细菌，它们将有毒的亚砷酸盐[As（III）]转化为毒性较小的砷酸盐[As（V）]，很容易用化学和生物捕集剂去除。在这项研究中，基因组和宏基因组方法与基于培养的测定平行进行（示意图），使得有可能破译地下水砷营养微生物组的系统发育多样性，并阐明其遗传决定因素。
从孟加拉国蒙希甘杰和昌德布尔地区的六个受砷污染（平均砷浓度为 0.23mg/L）的地下水样本中回收了 72 株分离株。23 株分离株携带高丰度的亚砷酸盐外排泵（arsB）基因，10 株分离株携带亚砷酸盐氧化酶（aioA）基因，最低抑菌浓度（MIC）范围很宽，从 2 到 32mM，证实了它们在亚砷酸盐代谢中的作用。物种丰富度和微生物群落结构存在相当大的异质性。这些多样性主要由变形菌门、厚壁菌门和酸杆菌门的微生物类群组成。通过这些组合方法，我们已经确定了一些潜在的候选者，如假单胞菌、不动杆菌、嗜麦芽寡养单胞菌、寡养单胞菌、副伯克霍尔德菌、丛毛单胞菌和克雷伯氏菌，以及相关的功能基因（arsB、acr3、arsD、arsH、arsR），它们可以显著促进亚砷酸盐的解毒、积累和固定。
基于培养的和非培养的鸟枪法宏基因组研究阐明了砷营养微生物组及其在砷生物地球化学转化中的功能。这些发现为进一步在孟加拉国和其他受砷污染地区进行大规模的砷营养微生物组及其在砷生物地球化学转化中的并发功能研究奠定了基础。
