Enviromicrobiology, Ecotoxicology and Ecotechnology Research Laboratory, Department of Ecological Studies, University of Kalyani, Nadia, Kalyani, 741235, West Bengal, India.
International Centre for Ecological Engineering, University of Kalyani, Kalyani, 741235, West Bengal, India.
Biodegradation. 2018 Aug;29(4):323-337. doi: 10.1007/s10532-018-9835-z. Epub 2018 May 22.
The aim was to isolate, characterize, and explore potentials of gut bacteria from the earthworm (Metaphire posthuma) and imply these bacteria for remediation of Cu(II) and Zn(II). An extracellular polymeric substance (EPS) producing gut bacteria (Bacillus licheniformis strain KX657843) was isolated and identified based on 16S rRNA sequencing and phylogenetic analysis. The strain showed maximum tolerance of 8 and 6 mM for Cu(II) and Zn(II) respectively. It removed 34.5% of Cu(II) and 54.4% of Zn(II) at 25 mg L after 72 and 96 h incubation respectively. The bacteria possessed a great potential to produce indole acetic acid (38.49 μg mL) at 5 mg mL L-tryptophan following 12 days incubation. The sterilized seeds of mung beans (Vigna radiata) displayed greater germination and growth under bacterium enriched condition. We observed that the bacterial strain phosphate solubilization ability with a maximum of 204.2 mg L in absence of Cu(II) and Zn(II). Endowed with biosurfactant property the bacterium exhibited 24% emulsification index. The bacterium offered significant potential of plant growth promotion, Cu(II) and Zn(II) removal, and as such this study is the first report on EPS producing B. licheniformis KX657843 from earthworm which can be applied as powerful tool in remediation programs of Cu(II) and Zn(II) contaminated sites.
目的是从蚯蚓（Metaphire posthuma）中分离、鉴定和探索肠道细菌的特性，并将这些细菌应用于 Cu(II) 和 Zn(II) 的修复。根据 16S rRNA 测序和系统发育分析，从蚯蚓肠道中分离出并鉴定出一种产胞外聚合物（EPS）的细菌（地衣芽孢杆菌 KX657843）。该菌株对 Cu(II) 和 Zn(II) 的最大耐受度分别为 8 和 6 mM。在 72 和 96 h 孵育后，该菌株分别在 25 mg L-1 时去除了 34.5%的 Cu(II)和 54.4%的 Zn(II)。该细菌在 5 mg mL L-tryptophan 条件下培养 12 天后，具有产生吲哚乙酸（38.49 μg mL）的巨大潜力。在细菌富集条件下，灭菌绿豆种子的发芽和生长情况更好。我们观察到，在没有 Cu(II) 和 Zn(II) 的情况下，该菌株的溶磷能力最大，可达 204.2 mg L-1。该细菌具有生物表面活性剂特性，其乳化指数为 24%。该细菌在促进植物生长、去除 Cu(II) 和 Zn(II) 方面具有显著潜力，因此，这是首次报道从蚯蚓中分离出产 EPS 的地衣芽孢杆菌 KX657843，可作为修复 Cu(II) 和 Zn(II) 污染场地的有力工具。
