Department of Ecological Studies, University of Kalyani, Kalyani, Nadia, 741235, West Bengal, India.
Department of Ecological Studies, University of Kalyani, Kalyani, Nadia, 741235, West Bengal, India; International Centre for Ecological Engineering, University of Kalyani, Kalyani, 741235, West Bengal, India.
J Environ Manage. 2019 Nov 15;250:109530. doi: 10.1016/j.jenvman.2019.109530. Epub 2019 Sep 12.
This work aimed at elucidating the role of bacteria present in the gut of the earthworm Metaphire posthuma in plant growth promotion and toxic trace elements (TTEs) bioremediation. We isolated and identified three bacterial strains Bacillus safensis (MF 589718), Bacillus flexus (MF 589717) and Staphylococcus haemolyticus (MF 589719) among which the Bacillus strains appeared to be significantly more potent than the Staphylococcus strain (P < 0.05) in promoting plant growth and removing TTE (Cr(VI), Cu(II) and Zn(II)) from aqueous media. These strains exhibited several plant growth promoting traits (e.g., indole acetic acid (IAA), gibberellic acid (GA) and ammonium ion production, 1-aminocyclopropane- 1-carboxylic acid (ACC) deaminase activity, and phosphate solubilizing potential). In a pot trial, the gut isolates improved Vigna radiata seed germination, and enhanced the leaf area (30-79%), total chlorophyll content (26-67%) and overall root-shoot biomass (32-83%) as compared to the control. Bacillus safensis and Bacillus flexus were equipotent in removing Cr(VI) (40.5 and 40.3%) from aqueous media; the former triumphed for Zn(II) removal (52.8%), while the latter performed better for Cu(II) removal (43.5%). The gut isolates successfully solubilized phosphate even in TTE-contaminated conditions. The results demonstrate that the earthworm's enteric bacteria possess inherent plant growth promoting, TTE resistance and phosphate solubilization (even under TTE stress) properties which can be further explored for their application in sustainable crop production and environmental management.
本研究旨在阐明环节动物赤子爱胜蚓肠道细菌在促进植物生长和修复有毒痕量元素（TTEs）方面的作用。我们从赤子爱胜蚓肠道中分离并鉴定了三株细菌，分别为芽孢杆菌（MF589718）、柔韧芽孢杆菌（MF589717）和溶血葡萄球菌（MF589719）。其中芽孢杆菌在促进植物生长和从水介质中去除 TTE（Cr(VI)、Cu(II)和 Zn(II)）方面比溶血葡萄球菌更为有效（P<0.05）。这些菌株表现出几种促进植物生长的特性（如吲哚乙酸（IAA）、赤霉素（GA）和铵离子的产生、1-氨基环丙烷-1-羧酸（ACC）脱氨酶活性和磷酸溶解能力）。在盆栽试验中，与对照组相比，肠道分离物提高了豇豆种子的发芽率，并分别提高了叶片面积（30-79%）、总叶绿素含量（26-67%）和整体根-茎生物量（32-83%）。芽孢杆菌和柔韧芽孢杆菌在从水介质中去除 Cr(VI)方面同样有效（分别为 40.5%和 40.3%）；前者在去除 Zn(II)方面表现出色（52.8%），而后者在去除 Cu(II)方面效果更好（43.5%）。肠道分离物即使在 TTE 污染的条件下也能成功溶解磷酸盐。研究结果表明，蚯蚓肠道细菌具有固有的促进植物生长、TTE 抗性和溶解磷酸盐的特性（即使在 TTE 胁迫下），这些特性可以进一步探索其在可持续作物生产和环境管理中的应用。
