Degradation studies of pendimethalin by indigenous soil bacterium Pseudomonas strain PD1 using spectrophotometric scanning and FTIR

Consortia of Bacillus sp. LY05 and Bacillus cereus LGY06 immobilized on coconut shell charcoal remediates pendimethalin and cadmium contaminated sites in-situ and alleviates peanut's continuous cropping obstacles

The use of artificial addition of microbial consortia into soils is a key strategy to simultaneously alleviate the common contamination and continuous cropping obstacles. This study established the coconut shell charcoal (CSC) LY05 +LGY06 by immobilizing Bacillus sp. LY05 and B. cereus LGY06 on CSC particles, which effectively accelerated the removal of pendimethalin as a possible human carcinogen (91.68 %) and Cd2 + (80.02 %) from the culture-solution, and displayed the prominent re-usability and stability compared with their free coculture consortium. This consortium could detoxify pendimethalin via serial nitro-reduction, oxidation, cyclization, carboxylation and hydroxylation reactions. CSC LY05 +LGY06 could rapidly degrade pendimethalin in sterile (90.01 %) and non-sterile (99.03 %) soils. Moreover, it notably reduced pendimethalin and Cd2+ residuals in pod kernels, pod shells, and plants of peanut growing in continuous cropping soil by 99.19 % and 94.02 %, 99.16 % and 93.94 %, and 98.94 % and 91.85 %, respectively, contrasted to the control. Meanwhile, it significantly promoted the pod yield (>1.28-fold) and quality of continuous cropping peanut by improving the plant agronomic trait, photosynthetic capacity, intracellular water metabolism, nutrient transport capacity, and metabolic activity. This study provides a novel insight into the safe production of agri-products in continuous cropping soils con-contaminated by pesticides and heavy metals.

Optimizing difenoconazole degradation via sequential photoelectrochemical oxidation and biodegradation treatments

The growing global demand for food has intensified the use of pesticides in conventional agriculture, raising concerns about their environmental contamination and persistence. This study proposes an integrated strategy for the degradation of difenoconazole (DFZ), combining photoelectrochemical oxidation (PECO) with biodegradation. A mixed metal oxide anode, Ti/(RuO2)0.8(Sb2O4)0.1(TiO2)0.1 was successfully synthesized via the ionic liquid method, and a mangrove-derived Bacillus sp. isolate was employed in a sequential treatment process. Individually, the Bacillus strain degraded 74.56 % of DFZ1 and 72.52 % of DFZ2, while PECO alone achieved a lower removal efficiency of 32 %. Notably, the sequential application of PECO followed by biodegradation enhanced the degradation rates to 77.81 % for DFZ1 and 74.45 % for DFZ2. Additionally, this combined approach significantly reduced chemical oxygen demand (70.6 %) and toxicity, as evidenced by improved lettuce seed germination indices. These findings underscore the potential of integrating PECO with biodegradation as a promising strategy for the remediation of difenoconazole (DFZ), offering new perspectives for the treatment of recalcitrant triazole compounds in contaminated environments.

Acetylcholinesterase-free colorimetric sensing platform for carbosulfan detection based on hollow PDA/MnO2 nanozyme

Rapid and accurate detection of carbosulfan residues in vegetables is important for ensuring food safety. Herein, based on the unique hydrolysis behavior of carbosulfan, a nanozyme-based colorimetric sensing platform was proposed for detection of carbosulfan. Hollow polydopamine/MnO2 nanoparticles (H-PDA/MnO2 NPs) with excellent oxidase-like activity were synthesized, which can promote the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) into blue oxidative product (oxTMB). Under acidic conditions, carbosulfan can be decomposed and produce reductive sulfide species (-SH), which are capable to disintegrate MnO2 NPs, resulting in decreased oxidase-like activity of H-PDA/MnO2 NPs. Based on the inhibitory effect on oxidase activity of H-PDA/MnO2 NPs, an acetylcholinesterase-free colorimetric assay was proposed for detection of carbosulfan with low limit of detection of 0.63 ng mL-1. Integrating test swabs with smartphone, a portable colorimetric sensor was constructed, showing great potential for on-site detection. To demonstrate the feasibility of this method, carbosulfan in real vegetable samples were determined.

Characterization of Sulfur Oxidizing Bacteria and Their Effect on Growth Promotion of Brassica napus L

Oil seeds sector is one of the major dynamic components of the agriculture world. Oil seeds such as canola (Brassica napus) require a higher quantity of sulfur (S), which is supplied through inorganic fertilizers. However, the overapplication of agro-chemicals to get higher yields of crops is harming the soil health. Therefore, the application of bacterial cultures with plant growth-promoting activity as biofertilizers ensures soil health maintenance and enhances crop productivity. To achieve this aim, the present research was initiated by procuring three sulfur-oxidizing bacteria (SOBs), namely, SOB 5, SOB 10, and SOB 38, from the Microbiology Department, PAU. In the initial assessment, all three SOB cultures showed resilience to pesticide toxicity at the recommended dosage, with the exception of ridomil. These cultures were later characterized morphologically, biochemically, and at the molecular level using 16s rRNA resulting in their identification as Enterobacter ludwigii strain Remi_9 (SOB 5), Enterobacter hormaechei strain AUH-ENM30 (SOB 10), and Bacillus sp. 5BM21Y12 (SOB 38). Functional characterization of these SOB cultures revealed their ability to exhibit multifarious plant growth-promoting traits. Bacillus sp. 5BM21Y12 showed greater functional activity, including high P solubilization (14.903 µg/mL), IAA production (44.28 µg/mL), siderophore production (13.89 µg/mL), sulfate ion production (0.127 mM), ammonia excretion (2.369 µg/mL), and Zn solubilization (22.62 mm). Based on the results of functional and molecular characterization, Bacillus sp. 5BM21Y12 was selected for field trials by formulating different treatments. Composite treatment, T8 (100% S + Bacillus sp. + pesticides) significantly enhanced growth parameters (plant height, root, and shoot biomass), yield attributes (siliqua length, test weight, number of siliqua/plant), yield parameter (total biomass and seed yield), quality parameter (crude protein and oil) as compared to all other sole treatments employed in the field. A combined application of non-pathogenic Bacillus sp. 5BM21Y12, with good functional activity enhanced yield of crop due to synergistic and additive interaction with fertilizer/pesticides. As biofertilizer application reduces the input of pesticides/fertilizers new inoculant formulations with cell protectors and the development of compatible pesticides should be searched to assure the benefits of integrated treatment.

Deciphering insights into rhizospheric microbial community and soil parameters under the influence of herbicides in zero-tillage tropical rice-agroecosystem

Extensive use of chemicals like herbicides in rice and other fields to manage weeds is expected to have a lasting influence on the soil environment. Considering this rationale, we aimed to decipher the effects of herbicides, Pendimethalin and Pretilachlor, applied at 0.5 and 0.6 kg ha-1, respectively on the rhizosphere microbial community and soil characteristics in the tropical rice field, managed under zero tillage cultivation. The quantity of herbicide residues declined gradually since application up to 60 days thereafter it reached the non-detectable level. Most of the soil variables viz., microbial biomass, soil enzymes etc., exhibited slight reduction in the treated soils compared to the control. A gradual decline was observed in Mineral-N, MBC, MBN and enzyme activities. Quantitative polymerase chain reaction results showed maximal microbial abundance of bacteria, fungi and archaea at mid-flowering stage of rice crop. The 16 rRNA and ITS region targeted amplicons high throughput sequencing microbial metagenomic approach revealed total of 94, 1353, and 510 species for archaea, bacteria and fungi, respectively. The metabarcoding of core microbiota revealed that the archaea comprised of Nitrososphaera, Nitrosocosmicus, and Methanosarcina. In the bacterial core microbiome, Neobacillus, Nitrospira, Thaurea, and Microvigra were found as the predominant taxa. Fusarium, Clonostachys, Nigrospora, Mortierella, Chaetomium, etc., were found in core fungal microbiome. Overall, the study exhibited that the recommended dose of herbicides found to be detrimental to the microbial dynamics, though a negative relation between residues and soil variables was observed that might alter the microbial diversity. The outcomes offer a comprehensive understanding of how herbicides affect the microbial community in zero tillage rice soil, thus has a critical imputation for eco-friendly and sustainable rice agriculture. Further, the long-term studies will be helpful in elucidating the role of identified microbial groups in sustaining the soil fertility and crop productivity.

Assessment of the ameliorative effect of curcumin on pendimethalin-induced genetic and biochemical toxicity

The present study aimed to assess the toxic effects of pendimethalin herbicide and protective role of curcumin using the Allium test on cytological, biochemical and physiological parameters. The effective concentration (EC₅₀) of pendimethalin was determined at 12 mg/L by the root growth inhibition test as the concentration reducing the root length by 50%. The roots of Allium cepa L. was treated with tap water (group I), 5 mg/L curcumin (group II), 10 mg/L curcumin (group III), 12 mg/L pendimethalin (group IV), 12 mg/L pendimethalin + 5 mg/L curcumin (group V) and 12 mg/L pendimethalin + 10 mg/L curcumin (group VI). The cytological (mitotic index, chromosomal abnormalities and DNA damage), physiological (rooting percentage, root length, growth rate and weight gain) and oxidative stress (malondialdehyde level, superoxide dismutase level, catalase level and glutathione reductase level) indicators were determined after 96 h of treatment. The results revealed that pendimethalin treatment reduced rooting percentage, root length, growth rate and weight gain whereas induced chromosomal abnormalities and DNA damage in roots of A. cepa L. Further, pendimethalin exposure elevated malondialdehyde level followed by antioxidant enzymes. The activities of superoxide dismutase and catalase were up-regulated and glutathione reductase was down-regulated. The molecular docking supported the antioxidant enzymes activities result. However, a dose-dependent reduction of pendimethalin toxicity was observed when curcumin was supplied with pendimethalin. The maximum recovery of cytological, physiological and oxidative stress parameters was recorded at 10 mg/L concentration of curcumin. The correlation studies also revealed positive relation of curcumin with rooting percentage, root length, weight gain, mitotic activity and glutathione reductase enzyme level while an inverse correlation was observed with chromosomal abnormalities, DNA damage, superoxide dismutase and catalase enzyme activities, and lipid peroxidation indicating its protective effect.