Findings reveal that the enhanced desilication by BM3 is associated with coordinated metabolic reprogramming and a more reactive EPS-mineral interface, providing an effective biological pretreatment for disrupting silicate matrices and improving scandium recovery from refractory tailings.
Abstract
Recovering scandium from silicate-rich tailings remains a major challenge due to refractory mineral matrices. Although biological desilication using microbial secretomes offers an eco-friendly solution, its industrial application is limited by the poor understanding of the intracellular metabolic programs that govern high-efficiency desilication. Here, an N-methyl-N'-nitro-N-nitrosoguanidine (NTG)-induced Bacillus mucilaginosus mutant, BM3, was evaluated using integrated whole-genome sequencing, transcriptomics, non-targeted metabolomics and mineral-interface measurements. BM3 achieved a 1.7-fold increase in desilication rate and subsequent chemical leaching of the bio-pretreated tailings substantially elevated scandium extraction from 21% (untreated) and 38% (wild-type-pretreated) to 53%. Spectroscopic analyses indicated that this modified secretome acted as a reactive interface, preferentially eroding recalcitrant pyroxene phases via carboxyl, amino, and hydroxyl ligand coordination. Multi-omics integration suggested that a coordinated metabolic reprogramming, including changes in phenylalanine metabolism, purine metabolism, and folate one-carbon metabolism, may underpin this phenotype. Overall, these findings reveal that the enhanced desilication by BM3 is associated with coordinated metabolic reprogramming and a more reactive EPS-mineral interface, providing an effective biological pretreatment for disrupting silicate matrices and improving scandium recovery from refractory tailings.
This study is the first to reveal the multienzyme mechanism of OTA degradation in the genus Pediococcus, providing a theoretical basis and genetic resources for probiotic- and enzyme-based bioremediation technologies.
The neonicotinoid insecticide thiamethoxam (THX) poses ecological risks and requires efficient bioremediation strategies. We isolated a highly efficient THX-degrading strain, Paenarthrobacter nicotinovorans GY-1, from contaminated agricultural soil. Under response surface-optimized conditions, GY-1 achieved an unprecedented THX degradation rate of 2.08 mg·L-1·h-1, the highest reported for a microorganism to our knowledge. Transcriptomics, enzyme assays, and carbon-source profiling showed that strain GY-1 suppresses glycolysis and reprograms central metabolism when THX is used as the sole nitrogen source. Q-TOF MS and 1D/2D NMR analyses unequivocally determined the structures of two purified intermediates, THX-1 and THX-2, providing direct structural evidence for nitro-reduction and deimination during THX biodegradation. On the basis of these confirmed intermediates, we proposed a nitro-reductive bacterial transformation pathway. This work reveals a microbial adaptation mechanism and provides a potent biocatalyst for the eco-friendly remediation of THX-contaminated environments.
Ziqing Gao, Shuya Wang, Xiu Yang et al.· Journal of Agricultural and...· 0 citations
The nonhemolytic properties, combined with the ability to lower surface tension and exhibit strong emulsification and oil displacement activities, highlight the potential of this biosurfactant for bioremediation, petroleum industry applications, and biomedical use.
Drifa Yalaoui-guellal, M. Moudache, Sunil Kumar Sahu et al.· Journal of Surfactants and D...· 0 citations
Biosurfactants from lactic acid bacteria are attractive as safe, multifunctional ingredients for food and cosmetic applications, yet many remain only partially characterized. An olive-derived strain was identified as Lactiplantibacillus plantarum J2K-1229 by 16S rRNA gene and genome-based phylogeny. Grown in rapeseed oil-containing medium, it secreted extracellular material with surface/interfacial activity, and its cell-free supernatant emulsified diverse plant oils (emulsification index after 24 h, 26.67−41.33%). A purified biosurfactant fraction gave carbohydrate- and lipid-positive, ninhydrin-negative thin-layer chromatography and Fourier transform infrared bands of a hydroxylated, ester- and carboxylic acid-containing lipid. Gas chromatography, NMR, and HPAEC–PAD indicated a complex, lipid-dominant mixture with major oleic and palmitic acids, NMR signals consistent with co-extracted phenyllactic acid-type metabolites, and fructose as the only detected monosaccharide. Genome mining revealed glucosyltransferases for glucose-based glycolipids but no fructosyltransferase, suggesting that the detected fructose may represent co-extracted free fructose, possibly released as a glucansucrase by-product. The preparation inhibited Candida albicans in disk diffusion assays and was non-cytotoxic to RAW 264.7 macrophages and HaCaT keratinocytes up to 200 ppm. In lipopolysaccharide-stimulated macrophages it suppressed nitric oxide production (88.07% at 200 ppm) and inducible nitric oxide synthase expression, and in cytokine-stimulated keratinocytes it reduced TARC, MDC, and RANTES expression. Overall, this olive-derived L. plantarum produces a multicomponent, glycolipid-containing biosurfactant preparation with emulsifying, antifungal, and anti-inflammatory activities suited to cosmetic and personal-care applications.
Jong Woo Hyeon, Min Hui Jeon, Jun-Tae Bae et al.· Journal of Microbiology and...· 0 citations
Nicotinic acid is vital in pharmaceuticals, feed, food, and cosmetics. Nitrilase can catalyze the conversion of 3-cyanopyridine to nicotinic acid, but its industrial application is limited by poor thermostability and substrate tolerance. In this study, nitrilase from Betaproteobacteria bacterium was engineered via multistrategy synergistic evolution, including C-terminal loop truncation, consensus mutation, loop engineering and protein surface engineering. Through iterative saturation mutagenesis, we obtained mutant 4 M (L194F/A201Q/S208L/M180Q-Δ47). Its activity reached 12.78 U/mL. After 1 h at 50 °C, 4 M retained 10.46 U/mL residual activity─3.25-fold higher than WT. Its melting and aggregation temperatures increased by 8.3 and 6.6 °C, respectively. Molecular dynamics revealed that enhanced thermostability resulted from reduced loop flexibility, strengthened hydrophobic interactions, and new hydrogen bonds. An engineered Vibrio natriegens strain produced 564.3 g/L nicotinic acid, a 5.8-fold increase over WT. This work provides mechanistic insights into nitrilase thermostability.
Qi Zhu, Lanxin Xiao, Yijie Sun et al.· Journal of Agricultural and...· 0 citations
