Biotechnological potential of Paenarthrobacter nicotinovorans ATCC 49919 for the microbial conversion of nicotine and tobacco extracts into 6-hydroxynicotine
Aug 2026· Brazilian Journal of Microbiology· Vol 57· 0 citations· 49 references
Medicine
TL;DR
Although not achieving near-stoichiometric yields reported for knockout-based systems, the described platform offers a controllable and feedstock-flexible approach for nicotine waste valorization.
Abstract
Nicotine-rich wastes from the tobacco industry represent an environmental liability but also a potential feedstock for value-added bioconversion. In this study, the biotechnological potential of Paenarthrobacter nicotinovorans ATCC 49919 for selective accumulation of 6-hydroxy-(L)-nicotine (6HLN), the first intermediate of the pyridine pathway, was evaluated under flask and bioreactor conditions. Two metabolic engineering strategies were explored: transcriptional silencing of the 6-hydroxynicotine oxidase gene (6hlnO) using a CRISPR/dCas9 system and overexpression of the nicotine dehydrogenase large subunit (ndhL) to enhance entry flux into the pathway. Among the tested strains, the ndhL-overexpressing derivative exhibited the highest 6HLN accumulation during growth (up to 1.78 g L⁻1; space–time yield 104.4 mg L⁻1 h⁻1). Resting-cell bioconversion experiments identified 100 g wet cell weight L⁻1 as an optimal biomass loading. Chemical inhibition of 6-hydroxy-L-nicotine oxidase with 0.8 mM ZnSO4 further expanded the 6HLN accumulation window without substantially impairing nicotine depletion. Scale-up experiments in a stirred bioreactor demonstrated effective conversion of both pure nicotine and tobacco-derived extracts, with matrix-dependent differences in conversion kinetics. Dissolved oxygen profiles correlated reproducibly with substrate depletion and product turnover, providing a potential online process control signature. Although not achieving near-stoichiometric yields reported for knockout-based systems, the described platform offers a controllable and feedstock-flexible approach for nicotine waste valorization.
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
Strategic bioconversion of lignocellulosic agro-wastes like sugarcane bagasse (SCB) into high-value Riboflavin is a rarely reported phenomenon. The present study explored a Riboflavin-producing bacterial strain,
Microbacterium proteolyticum
BWBTDIPO1 (GenBank Acc no.: PQ517523), isolated from the dumping area of Kolkata, West Bengal for its caliber to utilize SCB as a source of carbon and energy for the sustainable bio-production of the valuable nutraceutical under submerged fermentation (SmF) conditions. A strong association of bacterial growth (specific growth rate of μ = 0.325 h
-1
) with production of Riboflavin (yield of 397 ± 15.8 mgL
-
1, which amounts to 19.85 ± 2.0 mg per gram of SCB after 78 h) was recorded. Yeast extract peptone mineral salt media (YPMSM) was found to be the most suitable medium for the production. UV-Vis spectrophotometry and thin-layer chromatography (TLC) with an R
f
value of 0.83 confirmed that the metabolite was Riboflavin. The biochemical assays revealed that the strain utilized SCB components, including lignin, cellulose, and hemicellulose. Further confirmation of biomass deconstruction was assessed via FTIR, XRD, and FESEM analysis, where reports ensured successful deconstruction of SCB by the bacterial isolate. To complement the experimental findings, KEGG-based
in silico
pathway analysis was performed to explore potential metabolic routes associated with lignocellulosic biomass utilization and carbon metabolism. The predicted pathways provide a hypothetical framework for understanding biomass deconstruction and require experimental validation. This is the first report of Riboflavin production from waste SCB via bacterial treatment
(M. proteolyticum)
, indicating the novel nature of the strain and the methodology employed. Valorizable Riboflavin obtained from waste SCB can be a green alternative to chemical Riboflavin synthesis as well as bulk SCB waste management, promoting the concept of microbe-mediated waste-to-wealth conversion, thus contributing to circular bioeconomy.
Indrani Paul, S. Kali, Sonia Saha et al.· Frontiers in Chemical Engine...· 0 citations
It is demonstrated that culture optimization is an efficient biotechnological strategy to improve 3O-methylfunicone production and support the further investigation of this compound as a scaffold for anti-H.
M. Marques, Dalila N. Loose, Crislaine S. Lima et al.· Archives of Microbiology· 1 citation
2,4,6-Trinitrotoluene (TNT) contamination presents serious threats to ecological safety and human health due to its high toxicity, carcinogenicity, and environmental persistence. Although microbial bioremediation is eco-friendly and cost-effective, its efficiency is often limited by low removal rates and weak microbial tolerance under TNT stress. This study utilized biochar to facilitate microbial biotransformation of TNT and systematically elucidated its synergistic mechanisms. Four types of biochar from different waste sources were screened, among which the wood biochar (MBC) exhibited the optimal performance. With MBC amendment, the TNT removal efficiency increased from 46.2% (strain-only control) to 88.7% within 48 h at an initial TNT concentration of 100 mg/L. Meanwhile, the first-order kinetic rate constant rose from 0.01323 h-1 (strain-only) to 0.03987 h-1, revealing that MBC greatly accelerated the TNT removal rate. Biochar accelerated removal kinetics, alleviated TNT-induced growth inhibition of strain T22 via lowering aqueous TNT concentration, and stimulated extracellular polymeric substance secretion. Untargeted metabolomics revealed 330 up-regulated differential metabolites in the biochar-microbe system, indicating intensive metabolic reprogramming. Mechanistically, MBC directly enhanced TNT transformation via activation of the nitrotoluene degradation and cofactor biosynthesis pathways. The synergistic mechanisms were proposed to include: (1) weakened TNT exposure; (2) enhanced antioxidant metabolism; (3) activated core transformation pathways; and (4) supplemented basal metabolic supply. Although complete mineralization and soil-scale validation are beyond the present scope, our findings establish a mechanistic foundation for designing biochar-microbe systems for enhanced nitroaromatic remediation.
Bin Dong, Chengxu Lai, Meng-wei Han et al.· Environmental Research· 0 citations
60 candidate key genes associated with high xylose-to-ethanol yield in S. stipitis are identified, predominantly involved in the cell cycle pathway, including CDC15 and PHO81.
Hao Zou, Yuan-Jie Zhou, Sui-Yin Lin et al.· Life· 0 citations
Microbial biotransformation of para-hydroxycinnamic acids (pHCAs) such as para-coumaric, caffeic, ferulic and sinapic acids into vinylphenols is catalyzed by phenolic acid decarboxylases (PADs), while reduction to their corresponding aldehydes and alcohols is mediated by carboxylic acid reductases (CARs) and alcohol dehydrogenases (ADHs), respectively. The present study systematically evaluated a diverse set of endophytic and basidiomycetes fungi as whole-cell biocatalysts for the transformation of pHCAs into their corresponding vinylphenols and/or aldehydes and alcohols. Twenty-three fungal strains were screened for their PAD, CAR and ADH activities. Based on ultra-high-performance liquid chromatography–diode array detector (UHPLC-DAD) analysis, fourteen strains were selected for preparative-scale biotransformations across all four substrates. Previous literature largely emphasizes enzyme activity or single substrates, seldom covering all four pHCAs. The strain Umbelopsis sp. JAR-T demonstrated promising biotransformation of para-coumaric acid and ferulic acid to 4-vinylphenol (28% isolated yield) and 4-vinylguaiacol (40% isolated yield), respectively, with minimal by-product formation. The results highlight endophytic fungi as largely untapped and versatile biocatalysts for pHCA biotransformation and establish whole-cell fungal systems as robust, non-recombinant alternatives to engineered platforms. This integrated screening-to-preparative workflow provides a scalable framework for the production of value-added compounds with potential applications in the food, cosmetic and pharmaceutical industries.
A. Baskaran, Stefano Serra, El-Sayed R. El-Sayed et al.· Molecules· 0 citations
