Biotransformation and bioaccumulation of arsenic by Brevibacillus brevis isolated from arsenic contaminated region of West Bengal

Abstract

Microorganisms influence the fate of metals in environment. Increasing anthropogenic and geogenic activity had increase the risk of arsenic pollution and this has forced the future research area to involve microbes-metal toxicity to achieve bioremediation. The present study deals with the role of arsenite transforming bacteria and incorporates them into remediation design. Sample was collected from Haringhata in Nadia district which is a known arsenic contaminated zone. Out of six isolated bacteria one bacterium revealed as arsenic tolerant bacteria which shows molecular similarity with Brevibacillus brevis from 16s rRNA studies. It can tolerate upto 1000 mg/L of arsenite and 500 mg/L of arsenate. Both the arsenic species has toxic effects on its protein concentration. The strains can tolerate upto a certain limit after that their growth ceased. This strain can accumulate and also transform arsenite to arsenate. The transformation capacity of strain was assessed qualitatively and quantitatively. The strain can transform 90% of arsenite to arsenate. But the transformation capacity only reveals as detoxification mechanism and has no relation with their respiration. Morphological biochemical and molecular identification was done. As arsenate is absorbed into iron oxyhydroxides and get immobilize thus a remediation mechanism can be designed with this strain.

Isolation of Arsenic-Resistant Bacteria from Bengal Delta Sediments and their Efficacy in Arsenic Removal from Soil in Association withPteris vittata

“…However, another study (Banerjee et al 2013) reported that Brevibacillus brevis Strain S1 had tolerances of 500 mg L -1 and 1000 mg L -1 for arsenate and arsenite, respectively. This difference is likely due to the reduced condition of the soil, making arsenite predominant and thus, making the strain more tolerant of arsenite than of arsenate.…”

“…Similarly, in respect to bioaccumulation of arsenic, it was found that all three bacterial strains can accumulate arsenic but SS11 accumulated the most. Banerjee et al (2013) reported that Brevibacillus brevis strain S1 can accumulate a maximum of 27.1 mg L -1 of arsenic after 3 days of incubation. The heavy metal toxicity test also revealed that SS11 had greater metal tolerance than the other two strains, although all three showed tolerance against different heavy metals.…”

“…As stored intracellularly by bacteria can be estimated (Banerjee et al 2013), for which the bacterial isolates were grown in NB medium containing either 25 mg sodium arsenate or 10 mg Each day, 1 ml of the culture was removed and centrifuged at 10,000 rpm for 10 minutes to separate the media and bacterial biomass. The bacterial pellet was collected, treated with 65% nitric acid to digest the sample, and heated until colorless.…”

Fundamentals and Application Potential of Arsenic-Resistant Bacteria for Bioremediation in Rhizosphere: A Review

“…Release of As into the environment occurs predominantly due to both natural weathering processes and biological activities, thus broadening the As cycle with time and creating a global threat (Nickson et al, 2000;Smith et al, 2000;Chakraborty et al, 2002;Lloyd, 2002;Mukhopadhyay et al, 2002;Nordstrom, 2002;Bhattacharya et al, 2009;Banerjee et al, 2013). The most common available inorganic forms of As are arsenate [As(V)] and arsenite [As(III)] (Buchet and Lauwerys, 1981;Leonard, 1991;Mukhopadhyay et al, 2002).…”

“…The occurrence of different As forms and their mobility in soil depends on several environmental factors (Woolson, 1977). Groundwater with As at hazardous concentrations is widely used for domestic purposes and for irrigating field crops as well in different regions, especially in the Bengal-delta, China, Taiwan, Vietnam, the US, Argentina, Chile, and Mexico (Brammer, 2008;Banerjee et al, 2013). Irrigation of agricultural fields with such groundwater increases the concentration of As in crop fields, creating potential risk for biomagnification by entering into the food chain (Rahman et al, 2007;2008;Bhattacharya et al, 2009).…”