Microbiology Laboratory, Department of Botany, Burdwan University, 713104, West Bengal, India.
Microbiology Laboratory, Department of Botany, Burdwan University, 713104, West Bengal, India; Department of Botany, Government General Degree College, Singur, West Bengal, 712409, India.
J Hazard Mater. 2018 Jun 5;351:317-329. doi: 10.1016/j.jhazmat.2018.03.009. Epub 2018 Mar 7.
Heavy metal resistant PGPR mediated bioremediation, phytostimulation and stress alleviation is an eco-friendly method for sustainable agriculture in the metal contaminated soil. The isolation of such PGPR is highly demanding to reduce heavy metals in contaminated cultivated fields for agricultural benefit. The present study was successful to isolate a potent multi-heavy metal resistant PGPR strain, identified as Enterobacter aerogenes strain K6 based on MALDI-TOF MS, FAME analysis and 16S rDNA sequence homology, from rice rhizosphere contaminated with a variety of heavy metals/metalloid near industrial area. The strain exhibited high degree of resistance to Cd, Pb and As upto 4000 μg/mL, 3800 μg/mL and 1500 μg/mL respectively. Intracellular Cd accumulation of this strain was evidenced by AAS-SEM-TEM-EDX-XRF studies. Moreover, it showed several important PGP traits like IAA production, nitrogen fixation, phosphate solubilization, ACC deaminase activity even under high Cd stress (upto 3000 μg/mL). The combined effect of Cd resistance and PGP activities of this strain was manifested to the significant (p < 0.05) growth promotion of rice seedling under Cd stress by reducing oxidative stress (through antioxidants), stress ethylene and Cd uptake in seedlings. Thus K6 strain conferred Cd-tolerance in rice seedlings and could be applied as PGPR in contaminated fields.
耐重金属植物根际促生菌介导的生物修复、植物刺激和减轻胁迫是受污染土壤中可持续农业的一种环保方法。为了减少受污染农田中的重金属以促进农业生产，对这类 PGPR 的分离要求很高。本研究成功地从受多种重金属/类金属污染的水稻根际土壤中分离到一株具有多耐重金属能力的 PGPR 菌株，根据 MALDI-TOF MS、FAME 分析和 16S rDNA 序列同源性，将其鉴定为 Aerogenes 属的 Enterobacter aerogenes 菌株 K6。该菌株对 Cd、Pb 和 As 的抗性程度分别高达 4000μg/mL、3800μg/mL 和 1500μg/mL。通过 AAS-SEM-TEM-EDX-XRF 研究证实了该菌株对 Cd 的细胞内积累。此外，它还表现出几种重要的 PGP 特性，如 IAA 生产、固氮、溶磷、ACC 脱氨酶活性，甚至在高 Cd 胁迫下（高达 3000μg/mL）也是如此。该菌株的 Cd 抗性和 PGP 活性的综合作用表现为在 Cd 胁迫下显著（p<0.05）促进了水稻幼苗的生长，通过降低幼苗中的氧化应激（通过抗氧化剂）、胁迫乙烯和 Cd 摄取来实现。因此，K6 菌株赋予了水稻幼苗对 Cd 的耐受性，可作为受污染土壤中的 PGPR 使用。
