Organophosphate Degradation and Plant Growth-Promoting Activity of Soil Bacteria Isolated from Vegetable Farms in Benguet, Philippines

This study investigates the plant growth-promoting (PGP) characteristics and biodegradation capacity of organophosphate-tolerant soil bacteria isolated from vegetable farms in Benguet, Philippines. Three soil bacterial strains identified based on 16S rRNA sequences as Pseudomonas chlororaphis (M4C4-5), Pantoea allii (M1C5-1), and Mammaliicoccus sciuri (M1C4-15) tolerated up to 2,000 mg L-1 chlorpyrifos (CP) and malathion (MT) and exhibited PGP characteristics including nitrogen (N2) fixation, ammonia (NH3) production, phosphate (PO43-), and potassium (K) solubilizations, and productions of indole-3-acetic acid (IAA), siderophores, and gibberellin A3 (GA3). Growth analysis using minimal media with CP as the sole carbon source suggests a maximum population (10.11 log10 CFU) on day 5, achieved by P. chlororaphis (M4C4-5). The isolates showed degradation of the amended CP in the mineral salt medium. Remarkably, P. chlororaphis (M4C4-5) showed efficient degradation by 81.76%. Overall, this study provided new insights and application potential of novel soil bacteria in the bioremediation of OP pesticides while promoting plant growth and development by producing phytohormones and enzymes.