Pretilachlor-induced physiological, biochemical and morphological changes in Indian paddy field agroecosystem inhabited Anabaena doliolum

Herbicide pretilachlor impairs biofertilizer potential of Anabaena doliolum: Integrating proteomic responses, nitrogen fixation, and computational analysis

This study investigated proteomic alterations in Anabaena doliolum, a diazotrophic cyanobacterium native to Indian paddy fields, to elucidate the molecular basis of herbicide pretilachlor toxicity/tolerance. Proteomic analysis identified 325 proteins, with 124, 149, 179 and 190 proteins expressed at pretilachlor concentrations of 0 (control), 2, 5 and 10 μg/ml, respectively. At 2, 5 and 10 μg/ml, 67, 67 and 71 differentially expressed proteins were identified, involved in photosynthesis, carbon and nitrogen metabolism, protein synthesis, and redox homeostasis. Nitrogen fixation and heterocyst differentiation proteins displayed dose-dependent inhibition, except for slight induction at low dosages. Nitrogenase activity and heterocyst frequency observations further evidenced strong dose-dependent inhibition of nitrogen fixation and heterocyst differentiation. Transcript analysis revealed increased expression of sodA, sodB, and alr3090 at 2-10 μg/ml, with a notable decrease at 20 μg/ml. Molecular docking with pretilachlor yielded relative energy, LibDock scores with hotspot regions of interacting residues. FTIR spectroscopy exhibited alterations in the lipid profile due to oxidative membrane damage and adaptive measures. These findings dissect Anabaena doliolum's response mechanism to pretilachlor toxicity and provide a valuable reference for evaluating the potential risk posed by pretilachlor to native natural biofertilizers in paddy fields.

Cyanobacteria-Pesticide Interactions and Their Implications for Sustainable Rice Agroecosystems

Modern agricultural practices rely heavily on fertilizers and pesticides to boost crop yields, essential for feeding the growing global population. However, their extensive use poses significant environmental risks. Chemical-based fertilizers and pesticides persist in ecosystems, potentially harming ecological stability. Wetland rice farming utilizing nitrogen-fixing cyanobacteria has emerged as an ecofriendly alternative, drawing attention due to its capacity to mitigate pesticide-related issues. Cyanobacteria, capable of fixing atmospheric nitrogen, thrive in low-nitrogen conditions and can aid plant growth. Some species can also biodegrade pesticides, offering a means to clean up contaminated environments. Researchers are exploring ways to leverage cyanobacteria's nitrogen fixation and biodegradation abilities for ecofriendly biofertilizers and environmental cleanup. This approach presents promise for sustainable agriculture and environmental preservation. The current study delves into multiple studies to investigate global pesticide usage levels, primary categorization, and persistence patterns. It also investigates cyanobacterial distribution and their interactions with pesticides in wetland rice ecosystems, aiming to enable their use in sustainable agriculture. Additionally, the review provides a thorough summary of the literature's findings about the potential of cyanobacteria in pesticide degradation.

Degradation of pretilachlor and fenclorim and effects of these compounds on bacterial communities under anaerobic condition

Pretilachlor and safener fenclorim are the main components of herbicides widely applied to control weeds. Although some pure cultures of bacteria and fungi which degraded these compounds under aerobic conditions were isolated, no isolated pretilachlor- and fenclorim-degrading bacterial strains under anaerobic condition had been available. In this study, the degradation of these compounds and the effects of them on bacterial community structures were investigated under anaerobic conditions. The dissipation rates of pretilachlor and fenclorim in slurries were in the order: soil from paddy field ≈ sediment from river > sediment from mangrove. Moreover, three pretilachlor-degrading bacterial strains (Pseudomonas sp. Pr1, Proteiniclasticum sp. Pr2 and Paracoccus denitrificans Pr3) and two fenclorim-degrading strains (Dechloromonas sp. Fe1 and Ralstonia pickettii Fe2) isolated from a slurry of paddy soil utilized the substrates as sole carbon and energy sources under anaerobic conditions. The degradation of pure pretilachlor and fenclorim at various concentrations by corresponding mixed pure cultures followed the Michaelis-Menten model, with the maximum degradation was 3.10 ± 0.31 µM/day for pretilachlor, and 2.08 ± 0.18 µM/day for fenclorim. During the degradation, 2-chloro-N-(2,6-diethylphenyl) acetamide and 2,6-dimethylaniline were produced in pretilachlor degradation, and benzene was a product of fenclorim degradation. The synergistic degradation of both substrates by all isolated bacteria reduced the metabolites concentrations accumulated in media. This study provides valuable information on effects of pretilachlor and fenclorim on bacterial communities in soil and sediments, and degradation of these substrates by isolated bacteria under anaerobic condition.