Department of Microbiology and Biotechnology, University School of Sciences, Gujarat University, Ahmedabad, 380009, Gujarat, India.
Int Microbiol. 2023 Nov;26(4):1167-1183. doi: 10.1007/s10123-023-00366-w. Epub 2023 May 6.
The current study aimed to enhance exopolysaccharide production by Klebsiella variicolaSMHMZ46 isolated from the Zawar mines area in Udaipur, Rajasthan, India, by optimizing the medium with OFAT and a central composite design. The trial including sucrose (9.5%), casein hydrolysate (3%), and NaCl (0.5%) yielded the maximum EPS production as indicated by applying the CCD-RSM biostatistical program. The composition of exopolysaccharides produced by Klebsiella variicolaSMHMZ46 culture was characterized. Growth under Pb(II), Cd(II), and Ni(II) metal amended conditions induced EPS production relative to control. TLC was used for identifying the sugar residues of EPS, in addition to determination of both total carbohydrate and protein contents. According to FT-IR analysis, EPS can interact with metal ions via their functional chemical groups, thereby supporting their bioremediation potential. The metal removal efficiency of bacteria and their produced EPS in broth individually spiked with Pb(II), Ni(II), and Cd(II) was 99.18%, 97.60%, and 98.20%, respectively, and powdered EPS from contaminated water was 85.76%, 72.40%, and 71.53%, respectively. According to FEG-SEM observations, the surface morphology of EPS becomes rough, demonstrating sharp bumps after metal binding. A FEG-SEM analysis of the structure of EPS was performed; the surface structure of EPS (with metal) was more rigid than that of control EPS (without metal). The interaction between the EPS system and Pb(II) ions was investigated using FEG-SEM coupled with energy dispersive X-ray spectra, and a strong peak of C, O, and Pb elements was observed, indicating successful Pb adsorption. These findings suggest that EPS from Klebsiella variicolaSMHMZ46 has a good metal adsorbing nature and could be a promising biosorbent for metal bioremediation of contaminated water.
本研究旨在通过优化培养基（正交试验设计和中心复合设计）来提高从印度拉贾斯坦邦乌代浦的扎瓦尔矿区分离出的产黄克雷伯氏菌 SMHMZ46 的胞外多糖（EPS）产量。试验结果表明，在添加蔗糖（9.5%）、水解酪蛋白（3%）和 NaCl（0.5%）的培养基中，最大 EPS 产量最高。应用 CCD-RSM 生物统计程序表明，产黄克雷伯氏菌 SMHMZ46 培养物所产生的胞外多糖的组成。在 Pb(II)、Cd(II) 和 Ni(II)金属添加条件下的生长诱导 EPS 产量相对于对照增加。TLC 用于鉴定 EPS 的糖残基，除了确定总碳水化合物和蛋白质含量外。根据 FT-IR 分析，EPS 可以通过其功能化学基团与金属离子相互作用，从而支持其生物修复潜力。单独在含 Pb(II)、Ni(II) 和 Cd(II) 的菌液和 EPS 中加入重金属，细菌的金属去除效率分别为 99.18%、97.60%和 98.20%，从污染水中提取的 EPS 分别为 85.76%、72.40%和 71.53%。根据 FEG-SEM 观察，EPS 的表面形态变得粗糙，在金属结合后显示出尖锐的凸起。对 EPS 结构进行了 FEG-SEM 分析，结果表明 EPS（含金属）的表面结构比对照 EPS（不含金属）更硬。通过 FEG-SEM 结合能谱分析研究了 EPS 系统与 Pb(II)离子的相互作用，观察到 C、O 和 Pb 元素的强峰，表明成功吸附了 Pb。这些发现表明，产黄克雷伯氏菌 SMHMZ46 的 EPS 具有良好的金属吸附特性，可作为受污染水金属生物修复的有前途的生物吸附剂。
