Isolation and Characterization of Arsenic-Tolerable Bacteria from Groundwater and Their Implementation on Rice Seedling's Shoot and Root Enhancement

Abstract

Arsenic exerts detrimental impacts on primary metabolism in plants, leading to reduced crop yield. Some arsenic-resistant plant growth-promoting bacteria (PGPB) help plants by providing some plant hormones to sustain their growth and development under arsenic stress. Here, seven different species of Bacillus were isolated from arsenic-contaminated groundwater of West Bengal, India. Those species were capable of growing in the presence of > 3.12 g/L arsenate (AsV) and > 0.65 g/L arsenite (AsIII) salts and also resist different heavy metals like Cu²⁺, Fe²⁺, Co²⁺, Zn²⁺, Pb²⁺, etc. They were susceptible to multiple groups of antibiotics like beta-lactam, aminoglycosides, etc. All species were capable of detoxifying arsenite and influenced rice seedlings' growth in the presence of arsenic salts by their capabilities like nitrogen-fixing ability, phosphate solubilization, indole 3-acetic acid (IAA), gibberellic acid (GA), proline production, etc. Most species helped enhance root and shoot lengths under arsenic stress. These primary findings suggest that those Bacillus spp. could be used as potential bio-fertilizers in arsenic-contaminated agricultural fields.