Isolation and characterization of arsenic resistant bacteria from tannery wastes and agricultural soils in Thailand

Abstract

Highly arsenic resistant bacteria (27 isolates), which had a minimum inhibitory concentrations (MICs) for arsenite and arsenate of ≥ 40 mM and > 400 mM, respectively, were isolated from tannery wastes and agricultural soils collected in Central Thailand. On the basis of the morphological, cultural, physiological and biochemical characteristics, and on the principal ubiquinone component and 16S rRNA gene sequence analyses, they were identified as nine isolates each of Klebsiella (Groups 1 and 8) and Acinetobacter (Groups 2, 3 and 7), four isolates each of Pseudomonas (Groups 4 and 6) and Comamonas (Group 5), and one isolate of Enterobacter (Group 9). From these 27 isolates, only one isolate, A3-3 from the genus Comamonas, appeared potentially capable of oxidizing arsenite to arsenate, as determined by silver nitrate staining of arsenite agar plates after colony growth.

Arsenic interception by cell wall of bacteria observed with surface-enhanced Raman scattering

“…However, no redox transformation of As occurred (results are not shown). In agreement with previous reports, As resistance without a redox-based metabolism is relatively common (Chitpirom, et al, 2009). The As-resistant bacteria in our study may develop As resistance mechanisms by minimizing the amount of As entering the cell (Chowdhury et al, 2009).…”

“…They were identified as belonging to four genera capable of tolerating high As concentrations (Chitpirom, et al, 2009;Escalante et al, 2009). Among the four genera, Pseudomonas is the most widely reported genus detected in As contaminated soils (Achour et al, 2007;Escalante, et al, 2009;Huang et al, 2010), As-free soils (Jackson et al, 2005), and natural groundwater (Liao et al, 2011).…”

“…The MIC of As(III) and As(V) for each bacteria was determined in to be the range 10 to 500 mM; however, these values could not directly compare with other reports because of the differences in growth conditions (Chitpirom, et al, 2009;Jackson, et al, 2005;Liao, et al, 2011;Pepi, et al, 2011). To screen for bacteria that could regulate and change As oxidation states, As speciation was determined using HPLC-AFS.…”

“…As-resistant microorganisms are referred to multiple genus including Bacillus, Klebsiella, Acinetobacter, Pseudomonas, Comamonas, Enterobacter (Chitpirom, et al, 2009), Campylobacter (Wang, et al, 2009), Leptospirillum (Tuffin et al, 2006), Aeromonas, Aureobacterium, Escherichia, Micrococcus, Rhodococcus, and Stenotrophomonas (Anderson and Cook, 2004;Clausen, 2000). Among these microorganisms, a well known efflux-based resistance mechanism is attributed to the presence of As resistance genes, such as arsR, arsA, arsB, arsC, arsD, arsH, arsM, and TnLfArs.…”

“…One gram of soil sample or 1 ml of groundwater sample was added into 10 ml of a chemically-defined liquid medium (CDM), and incubated at 30°C with shaking (200 rpm) in the dark for 48 h. The CDM consisted of three kinds of nutrients (Chitpirom et al, 2009) supplemented with arsenite (NaAsO 2 : 0, 5, 10, and 20 mM) or arsenate (Na 3 AsO 4 : 0, 5, 10, and 20 mM) at pH 7.0. The culture was expanded by subculturing twice.…”