Plant growth-promoting Bacillus cereus MCC3402 facilitates rice seedling growth under arsenic-spiked soil

Abstract

Microorganisms can solve the global problem of arsenic (As) contamination in soil and water, by eliminating the hazardous metalloid from contaminated habitats. A native As-resistant PMM6 strain was isolated from the tainted agricultural field in Durgapur, India. Following phenotypic investigations, fatty acid methyl ester analysis, and 16S rDNA sequence-based homology, it was identified as Bacillus cereus. Various analytical techniques such as atomic absorption spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray fluorescence, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy studies revealed a positive correlation between the strain's resistance properties against arsenate (75 mM) and arsenite (25 mM) and the biosorption and bioaccumulation of arsenic. The strain exhibited several important plant growth-promoting traits, including indole-3-acetic acid production (110.0±0.33μg/mL), 1-aminocyclopropane-1-carboxylate deaminase activity (2334.2±1.90 nm α-ketobutyrate/mg protein/h), phosphate solubilization, and siderophore production (68.0±2%). These traits facilitated the growth augmentation of rice seedlings under As stress, both in terms of physiological and biochemical parameters. Compared to uninoculated soil, the use of strain PMM6 helped to reduce As mobilization and oxidative stress in rice seedlings growing in As-spiked soil. Therefore, strain PMM6 holds the potential as bioremediator to restore As-contaminated agricultural lands while also promoting the growth of rice seedlings. It could thus be utilized in the bioremediation of As-contaminated agricultural lands in the near future.