Optimizing malathion biodegradation by <i>Bacillus cereus</i> via a design of experiment framework

Bacteria have effectively been employed to biodegrade pesticides, and current research was envisioned to investigate malathion degradation by <i>Bacillus</i> sp. isolated from field soils. About 30.87–72.25% biodegradation was observed after 96 h with the <i>Bacillus</i> sp. when malathion was used as sole carbon, which increased to 45.77–100% after 240 h at initial malathion concentrations of 0.005–0.1%, respectively. The influence of co-substrates, pH, pesticide concentration, rpm, temperature, and inoculum doses were examined to further optimize malathion biodegradation, and the effect of these factors was investigated by the Taguchi design of experiments (DOE). The optimal biodegradation conditions were obtained at 0.1% (w/v), glucose and yeast extract, pH − 7, temperature − 40 °C, malathion concentration − 0.03% (v/v), agitation − 150 rpm, and inoculum dose − 2% (v/v). The biodegradation rate was boosted to 98% at optimal conditions within 36 h. Malathion degradation was confirmed by ultra-high performance liquid chromatography (UHPLC) studies, followed by the elucidation of three different biodegradation/transformation pathways through GC/MS analysis. Biodegradation analysis of malathion by GC/MS confirmed the formation of a monocarboxylic acid, malaoxon, mercaptosuccinic acid, and phosphorus moiety. These findings unequivocally corroborate that <i>Bacillus</i> sp. inherits immense potential for biodegrading malathion at a wide range of environmental conditions and provides a workable solution for bioremediation of malathion.