Integrative Taxonomy and Microbial Ecology Research Group, Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, India.
Department of Thematic Studies, Environmental Change, Linköping University, Linköping, Sweden.
Microbiologyopen. 2018 Oct;7(5):e00594. doi: 10.1002/mbo3.594. Epub 2018 Mar 25.
Elevated levels of arsenic (As) in aquifers of South East Asia have caused diverse health problems affecting millions of people who drink As-rich groundwater and consume various contaminated agriculture products. The biogeochemical cycling and mobilization/immobilization of As from its mineral-bound phase is controlled by pH, oxic/anoxic conditions, and different microbial processes. The increased As flux generated from ongoing biogeochemical processes in the subsurface in turn affects the in situ microbial communities. This study analyzes how the indigenous arsenite-oxidizing bacteria combat As stress by various biophysical alterations and self-adaptation mechanisms. Fifteen arsenite-oxidizing bacterial strains were isolated and identified using a polyphasic approach. The bacterial strains isolated from these aquifers belong predominantly to arsenite-oxidizing bacterial groups. Of these, the membrane-bound phospholipid fatty acids (PLFA) were characterized in seven selected bacterial isolates grown at different concentrations of As(III) in the medium. One of the significant findings of this study is how the increase in external stress can induce alteration of membrane PLFAs. The change in fatty acid saturation and alteration of their steric conformation suggests alteration of membrane fluidity due to change in As-related stress. However, different bacterial groups can have different degrees of alteration that can affect sustainability in As-rich aquifers of the Bengal Delta Plain.
东南亚含水层中砷（As）含量升高，导致了大量健康问题，影响了饮用富含砷地下水和食用各种受污染农产品的数百万人。As 从其矿物结合相的生物地球化学循环和迁移/固定受到 pH 值、需氧/缺氧条件以及不同微生物过程的控制。地下持续进行的生物地球化学过程产生的增加的 As 通量反过来又会影响原位微生物群落。本研究分析了土著亚砷酸盐氧化菌如何通过各种生物物理变化和自我适应机制来应对砷胁迫。使用多相方法分离和鉴定了 15 株亚砷酸盐氧化细菌菌株。从这些含水层中分离出的细菌菌株主要属于亚砷酸盐氧化细菌群。在培养基中不同浓度的 As(III)下生长的七种选定的细菌分离株中，对其膜结合磷脂脂肪酸（PLFA）进行了特征描述。这项研究的一个重要发现是，外部应激的增加如何导致膜 PLFA 的改变。脂肪酸饱和度的变化和它们的立体构型的改变表明，由于与 As 相关的应激的变化，膜流动性发生了变化。然而，不同的细菌群可能会有不同程度的改变，这可能会影响孟加拉三角洲平原富砷含水层的可持续性。
