Chakraborty Anirban, DasGupta Chanchal K, Bhadury Punyasloke
Department of Life Science and Biotechnology, Jadavpur University, Kolkata, 700032, West Bengal, India.
Integrative Taxonomy and Microbial Ecology Research Group, Department of Biological Sciences and Centre for Climate and Environmental Studies, Indian Institute of Science Education and Research Kolkata, Mohanpur, Nadia, 741246, West Bengal, India.
Heliyon. 2020 Jan 2;6(1):e03089. doi: 10.1016/j.heliyon.2019.e03089. eCollection 2020 Jan.
High arsenic concentration in groundwater is a severe environmental problem affecting human health, particularly in countries of South and South-East Asia. The Bengal Delta Plain (BDP) distributed within India and Bangladesh is a major arsenic-affected region where groundwater is the primary source of drinking water. Previous studies have indicated that members of the bacterial class constitute a major fraction of the microbial community in many of the aquifers within this region. Bacteria belonging to this class are known to be involved in redox cycling of arsenic as well as other metals such iron and manganese, thereby impacting arsenic mobilization and immobilization. While microbial diversity in arsenic-contaminated environments is generally assessed using universal 16S rRNA gene primers, targeted evaluation of Betaproteobacteria diversity remains poorly constrained. In this study, bacterial diversity was investigated in the groundwater from two shallow aquifers (West Bengal, India) based on 16S rRNA gene clone libraries and sequencing using a custom-designed pair of primers specific to . Specificity of the primers was confirmed as well as by the absence of PCR amplification of other bacterial classes. Four major families (, , and ) were detected among which members of represented 59% and 71% of the total community in each aquifer. The four OTUs (operational taxonomic units; 97% sequence identity) within were close phylogenetic relatives of bacteria within the genus known to solubilize phosphate minerals. Additionally, the OTUs belonging to were closely related to the members of the genera and , known to oxidize iron under microaerophilic conditions. These results suggest that members of can potentially influence iron and phosphorus cycling which can influence biogeochemistry in arsenic-contaminated aquifers of the BDP.
地下水中的高砷浓度是一个严重的环境问题，影响着人类健康，特别是在南亚和东南亚国家。分布在印度和孟加拉国境内的恒河三角洲平原（BDP）是一个主要的砷污染地区，地下水是主要的饮用水源。先前的研究表明，细菌类群的成员在该地区许多含水层的微生物群落中占主要部分。已知属于此类的细菌参与砷以及其他金属（如铁和锰）的氧化还原循环，从而影响砷的迁移和固定。虽然通常使用通用的16S rRNA基因引物来评估砷污染环境中的微生物多样性，但对β-变形菌多样性的靶向评估仍然受到很大限制。在本研究中，基于16S rRNA基因克隆文库，并使用一对针对β-变形菌定制设计的引物进行测序，对来自两个浅层含水层（印度西孟加拉邦）的地下水细菌多样性进行了研究。引物的特异性通过与其他细菌类群的PCR扩增缺失得到证实。检测到四个主要科（伯克氏菌科、产碱菌科、丛毛单胞菌科和甲基杆菌科），其中伯克氏菌科的成员在每个含水层的总群落中分别占59%和71%。伯克氏菌科内的四个OTU（操作分类单元；97%序列同一性）与已知能溶解磷矿物的伯克氏菌属内的细菌是近缘系统发育亲属。此外，属于伯克氏菌科的OTU与在微需氧条件下已知能氧化铁的贪铜菌属和嗜酸菌属的成员密切相关。这些结果表明，伯克氏菌科的成员可能会影响铁和磷的循环，进而影响BDP砷污染含水层中的生物地球化学。
