Identification of intermediates formed from the degradation of a pesticide mixture in agricultural soils by an immobilized bacterial consortium
Resumen
In Mexico, the intensive use of pesticides in agriculture has generated significant environmental impacts due to the accumulation of toxic compounds in the soil. Substances such as plaguicides, frequently used in agricultural fields, are highly persistent and toxic, affecting soil microbial biodiversity and posing a risk to human and environmental health. To address this problem, a bacterial consortium consisting of 7 strains used, immobilized on three types of supports: corn residue, biochar, and sodium alginate. These supports were selected for their high porosity, water retention capacity, and compatibility with microbial activity. Zeolite was also incorporated as an adsorbent, evaluating its effect in proportions of 0%, 5%, and 10% in different soil types (sandy, agricultural, and forest). The results indicated that the combination of the immobilized consortium with zeolite significantly improved the soil's physical and chemical conditions. Furthermore, colony-forming unit (CFU) counts performed monthly between February and May showed a high and constant microbial abundance, with values close to 10ยนยน CFU. Greater moisture retention was observed, especially in agricultural soils, and more stable pH regulation within ranges suitable for biological activity was observed. Cumulative CO2 production reflected greater metabolic activity in the immobilized soil treatments, suggesting a more active and functional microbial environment. Furthermore, it was found that treatments with 5% and 10% zeolite, in combination with biological supports, promoted greater stability in bacterial populations over time, representing an advantage in terms of microbial resilience in contaminated soils. These findings support the use of immobilized microorganisms and adsorbent materials as an effective, economical, and sustainable strategy for restoring agricultural soils impacted by pesticides.