Characterization of arsenic resistant bacteria from arsenic rich groundwater of West Bengal, India

Abstract

Sixty-four arsenic (As) resistant bacteria isolated from an arsenic rich groundwater sample of West Bengal were characterized to investigate their potential role in subsurface arsenic mobilization. Among the isolated strains predominance of genera Agrobacterium/Rhizobium, Ochrobactrum and Achromobacter which could grow chemolitrophically and utilize arsenic as electron donor were detected. Higher tolerance to As(3+) [maximum tolerable concentration (MTC): ≥10 mM], As(5+) (MTC: ≥100 mM) and other heavy metals like Cu(2+), Cr(2+), Ni(2+) etc. (MTC: ≥10 mM), presence of arsenate reductase and siderophore was frequently observed among the isolates. Ability to produce arsenite oxidase and phosphatase enzyme was detected in 50 and 34 % of the isolates, respectively. Although no direct correlation among taxonomic identity of bacterial strains and their metabolic abilities as mentioned above was apparent, several isolates affiliated to genera Ochrobactrum, Achromobacter and unclassified Rhizobiaceae members were found to be highly resistant to As(3+) and As(5+) and positive for all the test properties. Arsenate reductase activity was found to be conferred by arsC gene, which in many strains was coupled with arsenite efflux gene arsB as well. Phylogenetic incongruence between the 16S rRNA and ars genes lineages indicated possible incidence of horizontal gene transfer for ars genes. Based on the results we propose that under the prevailing low nutrient condition inhabitant bacteria capable of using inorganic electron donors play a synergistic role wherein siderophores and phosphatase activities facilitate the release of sediment bound As(5+), which is subsequently reduced by arsenate reductase resulting into the mobilization of As(3+) in groundwater.

Taurine resumed neuronal differentiation in arsenite-treated N2a cells through reducing oxidative stress, endoplasmic reticulum stress, and mitochondrial dysfunction

“…Notably, Agency for Toxic Substances and Disease Registry ranked As as the most hazard element in USA based on toxicity and hazard to human in 2011 (ATSDR 2011). Although As compounds could be used as respiratory metabolites in few species of bacteria, there are accumulating studies indicating that As is tremendously poisonous to human, and increased environmental As level has become more and more an emergent issue in the world (Sarkar et al 2013).…”

Dissimilatory Arsenate Reduction and In Situ Microbial Activities and Diversity in Arsenic-rich Groundwater of Chianan Plain, Southwestern Taiwan

“…It is possible that the endospore-forming capability of Firmicutes enabled them to survive under unfavorable (As-contaminated) conditions. Bacterial populations in As-rich groundwater were characterized not only by their potential abilities of As reduction, oxidation, and resistance but also by their potential abilities for m i n e r a l w e a t h e r i n g , c h e m o l i t h o t r o p h i c o r chemolithoautotrophic mode of metabolism, and potential to grow as heterotrophically utilizing multiple electron donors and acceptors [5,[42][43][44]. Members of the genera Acinetobacter, Herbaspirillum, Bacillus, Nitrospira, Arthrobacter, and Sphingomonas detected in the As-rich groundwater (Fig.…”

“…Although often isolated as heterotrophs, these bacteria can grow under aerobic or anaerobic oligotrophic environments using energy and reducing power from oxidation of various inorganic elements during CO 2 fixation or other anaerobic reactions [5,10,45]. Several bacterial strains of these genera have been reported in As-contaminated environments [5,9,10,19,44]; most of them exhibit weathering activity, which in turn influences As mobility [43]. The genera Acinetobacter and Bacillus dominated in the groundwater have been reported as potential dissimilatory As reducers in As-contaminated environments [9,10,46].…”

“…The genera Acinetobacter and Bacillus dominated in the groundwater have been reported as potential dissimilatory As reducers in As-contaminated environments [9,10,46]. In addition, bacterial genera like Acinetobacter, Herbaspirillum, Bacillus, and Massilia isolated from groundwater were reported to resist elevated concentration of As [44]. Metabolic robustness of these genera to withstand elevated concentration of As and to grow aerobically and anaerobically utilizing diverse electron donors and acceptors signified their potential in As biogeochemical cycling [44].…”

“…In addition, bacterial genera like Acinetobacter, Herbaspirillum, Bacillus, and Massilia isolated from groundwater were reported to resist elevated concentration of As [44]. Metabolic robustness of these genera to withstand elevated concentration of As and to grow aerobically and anaerobically utilizing diverse electron donors and acceptors signified their potential in As biogeochemical cycling [44]. Enumerations of different microbial activities in As-rich groundwater were achieved by MPN methods.…”