Investigation of Arsenic-Resistant, Arsenite-Oxidizing Bacteria for Plant Growth Promoting Traits Isolated From Arsenic Contaminated Soils

Abstract

The menace of arsenic (As) pollution being severe warrants opting for low cost microbial remediation strategies. The present study of identifying suitable bacterial strains led to isolation of eleven As-tolerant strains from the As contaminated rhizosphere soils of West Bengal, India. They were found to oxidize/reduce 55%-31.6% of 5 mM As(III) and 73%-37.6% of 5 mM As(V) within 12 hrs. The four isolates (BcAl-1, JN 73, LAR-2 and AR-30) had high level of As(III) oxidase activity along with higher level of As(V) and As(III) resistance. The presence of aoxB gene was observed in these four As(III) oxidizing isolates. Evaluation of plant growth promoting characteristics revealed that BcAl-1 (Burkholderia cepacia), JN73 (Burkholderia metallica), AR-30 (Burkholderia cenocepacia) and LAR-2 (Burkholderia sp) had enormous plant growth-promoting characteristics (PGP), including ability to solubilize phosphate, siderophore production, indole acetic acid like molecules production, ACC deaminase production and nodule formation under As stressed condition. BcAl-1 and JN73 emerged as the most promising traits in As removal as well as plant growth promotion.