Phase II Glycosylation of Metronidazole in Tomato (Lycopersicum esculentum) and Basil (Ocimum basilicum): Implications for Plant-Mediated Transformation and Environmental Risk
2026· Journal of the Brazilian Chemical Society· 0 citations
TL;DR
The findings expand the current understanding of plant-mediated phase II transformation of MNZ and highlight the importance of considering transformation products, in addition to the parent compound, when evaluating their environmental fate and potential ecological impact in soil-plant systems.
Abstract
To investigate the uptake, physiological responses, and metabolism of metronidazole (MNZ), a widely used nitroimidazole antibiotic and emerging environmental contaminant, tomato (Lycopersicum esculentum) and basil (Ocimum basilicum) were selected as representative edible crops because of their agricultural relevance and contrasting physiological responses to environmental stress. The specimens were grown in MNZ-contaminated soil (250, 500, and 750 mg kg-1). Thin-layer chromatography coupled with densitometric analyses monitored MNZ uptake and metabolite formation, whereas ultra-high-performance liquid chromatography coupled with diode-array detection and tandem mass spectrometry analyses identified di- and triglycosylated MNZ derivatives, providing direct analytical evidence of plant-mediated phase II glycosylation. Tomato showed greater tolerance to MNZ exposure than basil. Although the bioconcentration (0.011 to 0.111) and translocation (0.14 to 0.49) factors of MNZ indicate low to moderate accumulation, the risk quotient values demonstrate high ecological risk (considering only the parent compound). Overall, these findings expand the current understanding of plant-mediated phase II transformation of MNZ and highlight the importance of considering transformation products, in addition to the parent compound, when evaluating their environmental fate and potential ecological impact in soil-plant systems.
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
Nuts are widely consumed worldwide and valued for their high nutritional quality. Tree nuts are, however, prone to colonization by various fungal genera that can cause spoilage and lead to the formation of toxic secondary metabolites, among which mycotoxigenic Aspergillus (A.) species are of particular concern because they produce hepatotoxic aflatoxins (AFs). In this study, untreated, shelled walnuts, hazelnuts, cashews, pistachios, and peanuts were surface-sterilized, inoculated with different A. flavus strains and incubated under controlled conditions. The concentrations of AFs and sterigmatocystin (STC) in the edible kernels were quantified by an ultra-high-performance liquid chromatography method, coupled with tandem mass spectrometry (UHPLC-MS/MS). In walnuts inoculated with five A. flavus strains, toxin production was highly strain dependent: four strains produced AFB1 in a wide range from 0.18 µg/kg to > 11,000 µg/kg, three strains formed AFB2 (3.58-1,411 µg/kg), and three strains synthesized STC (0.26–262 µg/kg), whereas one strain did not generate any AFs or STC, and none of the strains produced AFG1 or AFG2. In pistachios, inoculation with strains AF70 and CBS119.62 did not result in detectable AF formation, in contrast to hazelnuts, cashews, and peanuts, on which these strains yielded measurable toxin levels (AFB1: hazelnuts 0.11–3.56 µg/kg, cashews 0.15–0.16 µg/kg, peanuts 0.06–17.9 µg/kg; AFB2: hazelnuts 0.13–0.18 µg/kg, cashews < LOQ, peanuts 0.26–7.59 µg/kg; STC: hazelnuts 0.08 µg/kg, peanuts 5.28 µg/kg). Overall, markedly higher concentrations of A. flavus toxins were detected in walnuts than in the other nut types, identifying walnuts as a particularly susceptible matrix and indicating that AF and STC contamination of walnuts may pose an increasing food-safety challenge under future climate-change scenarios.
Sarah Schneidemann-Bostelmann, Franka Nöth, S. Asam et al.· Mycotoxin Research· 0 citations
Dry lenticel rot, caused by the ascomycete Ramularia mali, is an emerging postharvest threat to apple production in European alpine regions. Despite its increasing prevalence, established control strategies remain unavailable. This study evaluated the efficacy of 16 fungicides, including succinate dehydrogenase inhibitors (SDHIs; Group 7), demethylation inhibitors (DMIs; Group 3), quinone outside inhibitors (QoIs; Group 11), and multi-site inhibitors, alongside two plant fortifiers. Furthermore, the potential of the ripening inhibitor 1-methylcyclopropene (1-MCP) was tested after harvest. In vitro sensitivity assays showed that most tested active substances had limited inhibitory effects, with the exception of metiram and prothioconazole, which achieved 100% growth inhibition at 100 mg L−1. Two-year field trials largely reflected these findings, although the plant fortifier acidic clay provided a significant reduction in symptom expression, comparable to the levels achieved by prothioconazole. Notably, application of 1-MCP markedly mitigated disease progression, lowering symptom expression by up to 82–89%. The highest level of control was achieved through the combined application of different fungicides in an integrated strategy followed by 1-MCP application in postharvest. These findings suggest that senescence management may contribute to controlling R. mali in commercial apple production. However, the physiological mechanisms underlying the effect of 1-MCP require further investigation.
S. Primisser, U. Spitaler, Emma Rizzolli et al.· Frontiers in Plant Science· 0 citations
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
Background: Imidacloprid, a widely used neonicotinoid insecticide, is routinely applied to control pests in Astragalus membranaceus var. mongholicus, a crucial medicinal herb producing Astragali Radix. However, the early short-term transcriptional and metabolic responses of its seedlings under imidacloprid gradient stress remain poorly characterized. Methods: In this study, 80-day seedlings were subjected to three foliar spray treatments: blank control (CK), the recommended imidacloprid concentration (2000-fold dilution, 475 mg·L−1), and an excessively high concentration (500-fold dilution, 1900 mg·L−1). Leaf samples were harvested 24 h post-treatment for untargeted ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC–MS/MS) metabolomics (6 biological replicates) and RNA-seq transcriptome sequencing (3 biological replicates). Results: The low- and high-dose treatments induced 1076 and 860 differential metabolites and 6818 and 7283 differentially expressed genes, respectively. Flavonoids, saponins, terpenoids, amino acid metabolites, and energy-related pathways were prominently affected. KEGG enrichment indicated activation of flavone/flavonol biosynthesis, phenylpropanoid metabolism, amino acid metabolism, MAPK signaling, cutin/suberin/wax biosynthesis, and ABC transporter pathways, whereas high-dose exposure was associated with stronger changes in genes related to DNA replication and cell wall remodeling. Integrated network analysis highlighted CHS, PAL, MYC2, KCS, and ABCG40 as candidate regulators linking stress signaling, secondary metabolism, and metabolite transport. Conclusions: Seedlings of A. membranaceus var. mongholicus exhibit dose-dependent acute responses to imidacloprid. Moderate pesticide exposure primarily activates defensive secondary metabolism, whereas excessive dosage triggers genome-wide transcriptional reprogramming. This work identifies key metabolic pathways and hub genes, offering candidate molecular markers for investigating pesticide stress adaptation in medicinal Astragalus and guiding standardized pesticide application in cultivation.
Dabao Yin, Xue Li, Li Zhou et al.· Genes· 0 citations
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.
Iustin-Tiberius Munteanu, Ana Huşleag, Robert Iustin Susanu et al.· Brazilian Journal of Microbi...· 0 citations
