School of Studies in Biotechnology, Pt. Ravishankar Shukla University, Raipur, 492 010, India.
Department of Microbiology and Biotechnology, Jnana Bharathi Campus, Bangalore University, Bengaluru, 560 056, India.
Arch Microbiol. 2020 Apr;202(3):567-578. doi: 10.1007/s00203-019-01773-2. Epub 2019 Nov 18.
Arsenic (As) resistant indigenous bacteria with discrete minimum inhibitory concentration values for arsenate [As(V)] and arsenite [As(III)] were isolated from the paddy fields of different regions of Chhattisgarh, India, following enrichment culture technique. Evaluation of the plant growth promoting (PGP) properties of the isolates revealed that two rod-shaped Gram-positive bacteria viz., ARP2 and ART2 acquired various PGP traits, including phosphate solubilization, production of siderophore, indole acetic acid, ammonia, and exopolysaccharide. Both the isolates significantly increased (40-80%) the root length of Oryza sativa L. even under As-exposure. Sequencing of 16S rRNA gene identified these isolates as Bacillus nealsonii strain ARP2 and Bacillus tequilensis strain ART2, respectively. Isolate ARP2 exhibited arsenate reductase activity thereby rapidly reduced As(V) into As(III), achieving a reduction rate of 37.5 μM min. Alike, strain ART2 was capable of oxidizing As(III) into As(V) via arsenite oxidase enzyme, and revealed the oxidation rate of 21.8 μM min. Quantitative estimation of As through atomic absorption spectrophotometer revealed that the isolates ARP2 and ART2 removed 93 ± 0.2% and 77 ± 0.14% of As(V) and As(III), respectively, from As-containing culture media. The FTIR analysis showed the interaction of As with the cell membrane and was further confirmed by SEM and TEM techniques, which marked the increase in cell volume owing to successive accumulation of As. The As-resistant and PGP properties of above two isolates demonstrates their potentiality for sustainable bioremediation of As, and establishment of flora in As-rich environment.
从印度恰蒂斯加尔邦不同地区的稻田中，采用富集培养技术，分离出了对砷酸盐 [As(V)] 和亚砷酸盐 [As(III)] 具有离散最小抑制浓度值的耐砷土著细菌。对这些分离物的植物促生长 (PGP) 特性的评估表明，两种杆状革兰氏阳性细菌，即 ARP2 和 ART2，获得了各种 PGP 特性，包括磷酸盐溶解、产生铁载体、吲哚乙酸、氨和胞外多糖。在砷暴露下，这两种分离物都显著增加了（40-80%）Oryza sativa L. 的根长。16S rRNA 基因测序将这两个分离物分别鉴定为 Bacillus nealsonii 菌株 ARP2 和 Bacillus tequilensis 菌株 ART2。分离物 ARP2 表现出砷酸盐还原酶活性，从而迅速将 As(V)还原为 As(III)，还原率为 37.5 μM min。同样，菌株 ART2 能够通过亚砷酸盐氧化酶将 As(III)氧化为 As(V)，并表现出 21.8 μM min 的氧化率。原子吸收分光光度计定量测定砷表明，分离物 ARP2 和 ART2 分别从含砷培养基中去除了 93 ± 0.2%和 77 ± 0.14%的 As(V)和 As(III)。FTIR 分析表明砷与细胞膜相互作用，并通过 SEM 和 TEM 技术进一步证实，这标志着由于砷的连续积累，细胞体积增加。上述两种分离物的耐砷和 PGP 特性表明它们具有可持续生物修复砷和在砷丰富环境中建立菌群的潜力。
