Sharma Pratishtha, Iqbal Mohd Zobair, Chandra Ram
Department of Environmental Microbiology, School of Earth and Environmental Science, Babasaheb Bhimrao Ambedkar University, (A Central University), Lucknow, 226025, Uttar Pradesh, India.
World J Microbiol Biotechnol. 2025 Aug 26;41(9):314. doi: 10.1007/s11274-025-04528-y.
Tannery sludge has highly toxic heavy metals like chromium (Cr), posing environmental and health risks. This research investigates the potential of Dactyloctenium aegyptium (L.) Willd. and the associated rhizobacterial communities for bacterial-assisted phytoremediation of tannery sludge, having 6403.16 ± 0.71 mg/kg Cr. The analyses of culturable bacterial communities resulted in the exploration of two highly potent plant growth-promoting strains (CRB2 and CRB5), out of the six culturable strains obtained. SEM imaging depicted robust bacterial colonization on the plant root surface, confirming active plant-microbe interaction. D. aegyptium showed significant Cr accumulation (4936 ± 1.34 mg/kg) within the tissues, followed by substantial translocation to shoots and leaves (TF = 1.01). With a BCF of 1.66 for Cr, D. aegyptium bespeaks evident hyperaccumulation potential. TEM imaging revealed the granular metal deposition in the plant tissues. Post-plant growth, the sludge exhibited an 80.3% reduction in Cr concentration, alongside enhanced physicochemical properties (reduced pH, increased organic matter, reduced metal content). Furthermore, metagenomics analyses showed that the growth of D. aegyptium drastically changed rhizobacterial communities, decreasing species richness and increasing functional pathways associated with stress responses and metal tolerance. Important genes (copA, czcA, nirA), enzymes (dioxygenases, trimethylamine-N-oxide reductase), and proteins (CsgE, DsbG), essential for the nitrogen cycle, chromium detoxification, and plant-microbe associations, were found to be involved in metabolic pathways. The study amalgamates morphophysiological and advanced metagenomic approaches to put forth an understanding of species-specific plant-microbe interactions for the development of scalable and sustainable remediation and engineering of rhizospheric microbiomes for eco-restoration of heavy metal-polluted industrial sites.
制革污泥含有高毒性重金属，如铬（Cr），对环境和健康构成风险。本研究调查了埃及龙爪稷（Dactyloctenium aegyptium (L.) Willd.）及其相关根际细菌群落对含6403.16±0.71 mg/kg铬的制革污泥进行细菌辅助植物修复的潜力。对可培养细菌群落的分析发现了两种高效的植物生长促进菌株（CRB2和CRB5），这是从获得的六种可培养菌株中筛选出来的。扫描电子显微镜成像显示细菌在植物根表面大量定殖，证实了植物与微生物之间的活跃相互作用。埃及龙爪稷在组织内显示出显著的铬积累（4936±1.34 mg/kg），随后大量转运到茎和叶中（转运系数TF = 1.01）。对于铬，埃及龙爪稷的生物富集系数为1.66，表明其具有明显的超积累潜力。透射电子显微镜成像揭示了植物组织中的颗粒状金属沉积。植物生长后，污泥中的铬浓度降低了80.3%，同时理化性质得到改善（pH值降低、有机质增加、金属含量降低）。此外，宏基因组学分析表明，埃及龙爪稷的生长极大地改变了根际细菌群落，降低了物种丰富度，并增加了与应激反应和金属耐受性相关的功能途径。参与氮循环、铬解毒和植物-微生物相互作用所必需的重要基因（copA、czcA、nirA）、酶（双加氧酶、三甲胺-N-氧化物还原酶）和蛋白质（CsgE、DsbG）被发现参与了代谢途径。该研究结合形态生理学和先进的宏基因组学方法，以理解物种特异性的植物-微生物相互作用，从而开发可扩展且可持续的修复方法，并对根际微生物群落进行工程改造，以实现重金属污染工业场地的生态恢复。
