Pesticide contamination has become a major environmental concern with organophosphates such as chlorpyrifos emerging as major pollutants posing significant risks to both ecosystems and human health. Chlorpyrifos is widely used in agriculture to control pests, however due to its persistence, its accumulation in soils can lead to long-term environmental damage. The objective of this study was to isolate and characterize chlorpyrifos-degrading bacteria from a tobacco field exposed to intensive pesticide use in T & uuml;rkiye. To achieve this, a selective enrichment strategy was employed to promote the growth of chlorpyrifos-degrading microorganisms. Two distinct experimental setups were established to target both normally growing and slower-growing bacteria: the first involved a 4-week incubation with weekly subculturing as described in the literature, while the second applied an 8-week incubation with biweekly subculturing. At the end of the enrichment period, bacterial loads were compared between the two groups. Four of the nine bacterial isolates were obtained from the newly tested long-term setup. Among all isolates, members of the genus Pseudomonas exhibited the best adaptation to the prolonged enrichment conditions. Additionally, isolates belonging to the genera Klebsiella, Sphingobacterium, and Peribacillus were isolated from the normally growing group. Two isolates (AB4 & AB15), identified as Sphingobacterium thalpophilum, were determined to be novel chlorpyrifos degraders. This is the first reported study from T & uuml;rkiye focusing on the biodegradation of chlorpyrifos by native soil bacteria. The findings revealed that various ecological areas, constitute potential sources for new microbial metabolic processes and these bacterial strains can be used in bioremediation studies.

Bacteria can synthesize a broad spectrum of multifunctional polysaccharides including extracellular polysaccharides (EPS). Bacterial EPS can be utilized in the food, pharmaceutical, and biomedical areas owing to their physical and rheological properties in addition to generally presenting low toxicity. From an ecological viewpoint, EPS are biodegradable and environment compatible, offering several advantages over synthetic compounds. This study investigated the EPS produced by Klebsiella oxytoca (KO-EPS) by chemically characterizing and evaluating its properties. The monosaccharide components of the KO-EPS were determined by HPLC coupled with a refractive index detector and GC-MS. The KO-EPS was then analyzed by methylation analysis, FT-IR and NMR spectroscopy to give a potential primary structure. KO-EPS demonstrated the ability to stabilize hydrophilic emulsions with various hydrophobic compounds, including hydrocarbons and vegetable and mineral oils. In terms of iron chelation capacity, the KO-EPS could sequester 41.9 % and 34.1 % of the most common iron states, Fe2+ and Fe3+, respectively. Moreover, KO-EPS exhibited an improvement in the viscosity of aqueous dispersion, being proportional to the increase in its concentration and presenting a non-Newtonian pseudoplastic flow behavior. KO-EPS also did not present a cytotoxic effect indicating that the KO-EPS could have potential applications as a natural thickener, bioemulsifier, and bioremediation agent.

The recent emergence of drug-resistant microorganisms and the prevalence of cancer diseases are both presenting substantial global public health concerns. Silver nanoparticles (AgNPs) have attracted significant attention and are increasingly employed in diverse biomedical applications as agents with antimicrobial and anticancer properties. The study herein focused on the biogenic synthesis of AgNPs employing the cell-free filtrate of the soil-derived bacterium Streptomyces pratensis as a reducing agent. AgNPs were characterized using UV-Vis, FTIR, FE-SEM, and TEM. The study assessed both the antibacterial and anticandidal modes of action, along with the potential anticancer properties of the biosynthesized AgNPs. The spherical, 17-44-nm biosynthesized AgNPs demonstrated strong antimicrobial and antibiofilm activities against pandrug-resistant (PDR) Gram-negative Klebsiella pneumoniae and pathogenic yeast Candida albicans, both of which were isolated from immunosuppressed patients. Dose-dependent interactions between the AgNPs and their anticancer activity were observed. The IC50 values of the AgNPs against the hepatocellular (HepG2) and colon carcinoma (HCT-116) cancer cell lines were approximately 16.5 mu g/mL and 11.5 mu g/mL, respectively. Furthermore, the antimicrobial mechanism of action of AgNPs revealed distinct leakage of sugar, DNA, and proteins from the cell membrane of both K. pneumoniae and C. albicans, as well as increased ROS generation. Moreover, the TEM micrographs depicted the distortion and damage experienced by the microbial cells after exposure to AgNPs. The findings of the current study suggest that biosynthesized AgNPs have the potential to serve as alternative therapeutic agents for combating drug-resistant K. pneumoniae, the yeast C. albicans, in addition to HepG2 and HCT-116 cells.

Mesotrione is an emerging environmental contaminant with potential hazards to agricultural environment and nontarget organisms. Microbes are major drivers of mesotrione biodegradation. However, understanding of the degradation characteristics, mechanisms and potential applications of the reported bacteria that can be utilized to eliminate mesotrione is very limited. Here, a novel mesotrione-degrading Klebsiella pasteurii CM -1 with excellent environmental adaptability was isolated, which could completely degrade 100 mg/L mesotrione within 20 h under the optimal condition. Metabolic pathway analysis showed that CM -1 degraded mesotrione to 2-(2hydroxyamino-4-(methylsulfonyl)benzoyl)cyclohexane-1,3-dione, 1,3-dihydro-3-hydroxy-6-(methylsulfonyl) benzo[c]isoxazol-3-yl)cyclohexane-1,3-dione and 2-amino-4-methylsulfonylbenzoic acid. The predicted toxicities of these metabolites were lower than that of mesotrione. Combining genomic analysis and RT-qPCR, nitroreductase-encoding genes nfsA and nfsB were identified as key players driving mesotrione biodegradation. Molecular docking results suggested that residues His215 and Arg218 of NfsA and Lys14, Thr41 and Phe124 of NfsB might be the key sites for their binding to mesotrione. Purified enzyme in vitro assays indicated that NfsA and NfsB could degrade mesotrione under various conditions, and converted it to the same products as CM -1. Some metal cations could significantly enhance the activity of NfsA and NfsB. The Km values of NfsA and NfsB for mesotrione were 0.453 and 1.075 mmol/L. Furthermore, CM -1 could rapidly remove 97.21/96.50% of mesotrione (50 mg/kg) in nonsterilized/sterilized soil within 4 d. This study provided an efficient bioresource with remediation potential for mesotrione residual pollution and new insights into the mechanism of bacterialmediated mesotrione degradation.