Sugitha S, Abirami G
Department of Biotechnology, School of Life Sciences, Vels Institute of Science Technology and Advanced Studies, Pallavaram, Chennai, Tamil Nadu, India.
Biodegradation. 2025 Jul 18;36(4):63. doi: 10.1007/s10532-025-10163-z.
The present study investigates the physicochemical, heavy metal, and microbiological characteristics of water and sediment samples from the Buckingham Canal, Chennai, to assess environmental pollution and explore the bioremediation potential of native bacterial isolates. The water and sediment samples revealed the concentration of heavy metals in the sequence Zn > Mn > Pb > Cu > Cr and Zn > Mn > Cu > Cr > Pb. Among 25 isolates, BCSS04 showed exceptional resistance, tolerating up to 2100 ppm (Pb), 1900 ppm (Zn, Mn, and Cr), and 1300 ppm (Cu), identified as Proteus mirabilis through 16S rRNA sequencing (GenBank accession: PP980976.1). Molecular analysis confirmed the presence of the pbrA gene, while antibiotic susceptibility profiling revealed multidrug resistance, suggesting potential co-selection of metal and antibiotic resistance traits. Growth profiling under metal-induced stress revealed the highest bacterial growth under Mn (0.654 to 0.996) and Pb (0.623 to 0.984). Uptake studies confirmed efficient biosorption capabilities, with peak Pb and Zn uptake reaching 4.23 and 4.21 mg/g, respectively, at 100 ppm. Bioaccumulation assays supported these findings, with maximum accumulation rates for Zn (69.67%) and Pb (67.11%) at 100 ppm, gradually decreasing with increasing concentrations due to saturation or stress effects. SEM and FTIR analyses demonstrated structural and biochemical changes in Proteus mirabilis under metal stress. Molecular docking further revealed strong interactions between heavy metals against Metallothionein SmtA exhibited the strongest interaction with Zn (binding energy: -9.8 kcal/mol), involving eight active residues (TYR A:18, GLY A:53, ASP A:73, ASP A:50, GLU A:55, ARG A:26, HIS A:119, GLY A:52). The integrated physiological, biochemical, and molecular insights affirm the potential of Proteus mirabilis as a promising candidate for bioremediation of heavy metal-contaminated environments.
本研究调查了钦奈白金汉运河水和沉积物样本的物理化学、重金属及微生物特征，以评估环境污染并探索本地细菌分离株的生物修复潜力。水和沉积物样本显示重金属浓度顺序为Zn＞Mn＞Pb＞Cu＞Cr以及Zn＞Mn＞Cu＞Cr＞Pb。在25株分离株中，BCSS04表现出非凡的抗性，可耐受高达2100 ppm（Pb）、1900 ppm（Zn、Mn和Cr）以及1300 ppm（Cu），通过16S rRNA测序（GenBank登录号：PP980976.1）鉴定为奇异变形杆菌。分子分析证实了pbrA基因的存在，而抗生素敏感性分析显示其具有多重耐药性，表明金属抗性和抗生素抗性特征可能存在共同选择。金属诱导胁迫下的生长分析表明，在Mn（0.654至0.996）和Pb（0.623至0.984）存在时细菌生长最高。摄取研究证实了其高效的生物吸附能力，在100 ppm时，Pb和Zn的最大摄取量分别达到4.23和4.21 mg/g。生物累积试验支持了这些发现，在100 ppm时，Zn（69.67%）和Pb（67.11%）的最大累积率最高，由于饱和或胁迫效应，随着浓度增加逐渐降低。扫描电子显微镜（SEM）和傅里叶变换红外光谱（FTIR）分析表明，金属胁迫下奇异变形杆菌发生了结构和生化变化。分子对接进一步揭示了重金属与金属硫蛋白SmtA之间的强相互作用，SmtA与Zn的相互作用最强（结合能：-9.8 kcal/mol），涉及八个活性残基（TYR A:18、GLY A:53、ASP A:73、ASP A:50、GLU A:55、ARG A:26、HIS A:119、GLY A:52）。综合的生理、生化和分子研究结果证实，奇异变形杆菌有潜力成为重金属污染环境生物修复的理想候选菌株。
