Arsenic resistance and accumulation by two bacteria isolated from a natural arsenic contaminated site

Abstract

Forty-three indigenous arsenic resistant bacteria were isolated from arsenic rich soil of Rajnandgaon district in the state of Chhattisgarh, India by enrichment culture technique. Among the isolates, two of the bacteria (As-9 and As-14) exhibited high resistance to As(V) [MIC ≥ 700 mM] and As(III) [MIC ≥ 10 mM] and were selected for further studies. Both these bacteria grew well in the presence of arsenic [20 mM As(V) and 5 mM As(III)], but the isolate As-14 strictly required arsenic for its survival and growth and was characterized as a novel arsenic dependent bacterium. The isolates contributed to 99% removal of arsenic from the growth medium which was efficiently accumulated in the cell. Quantitative estimation of arsenic through Atomic Absorption Spectrophotometer revealed that there was >60% accumulation of both As(V) and As(III) by the two isolates. Scanning Electron Microscopic analysis showed a fourfold increase in bacterial cell volume when grown in the presence of arsenic and the results of Transmission Electron Microscopy and energy-dispersive X-ray spectroscopy proved that such an alteration was due to arsenic accumulation. Such arsenic resistant bacteria with efficient accumulating property could be effectively applied in the treatment of arsenic contaminated water.

Alcaligenes faecalisassociated with Mimosa calodendron rizhosphere assist plant survival in arsenic rich soils

“…Similar data has been described by (Pandey and Bhatt, 2015) who showed increase in the area of one isolate as a positive response to As (V)-contaminated environment. The bioaccumulation of the isolated was confirmed by transmission electron microscopy (TEM) and EDX.…”

“…This morphology modification indicates metal accumulation and results from changes in the osmotic potential and cell turgor (Pandey and Bhatt, 2015).…”

Role of soil associated Exiguobacterium in reducing arsenic toxicity and promoting plant growth in Vigna radiata

“…based on16S rDNA gene sequence analysis (Gene Bank accession number: KC894600.1) [21] was used in the present study. The isolate was Gram positive, rod-shaped and resistant to high concentrations of As(V) (700 mM) and As(III) (180 mM).…”

Phosphate starvation response controls genes required to synthesize the phosphate analog arsenate

“…However, As V can be incorporated into arsenosugars and arsenolipids as a methylated pentavalent As-C bond, which is very stable and well documented in higher organisms (Dembitsky and Levitsky, 2004). Arsenic accumulation in bacteria also occurs (Takeuchi et al, 2007;Yan et al, 2014;Wang et al, 2015;Pandey and Bhatt, 2015) and in marine macroalgae is found as arsenohydrocarbons and arsenophospholipids (Francesconi and Kuehnelt, 2002;Francesconi, 2010;Raab et al, 2013). However, understanding why a microorganism accumulates arsenic or how it may use it remains to be understood.…”