Isolation and characterization of multitrait Bacillus spp. that exhibit <i>in vitro</i> bioremediation of heavy metals and pesticides

Six distinct Bacillus strains (<i>Bacillus amyloliquefaciens</i>, <i>Bacillus subtilis</i>, <i>Bacillus haynesii</i>, <i>Bacillus tequilensis</i>, <i>Bacillus licheniformis</i>, and <i>Bacillus halotolerans</i>) were identified. These strains demonstrated specialized phosphate (up to 65.13 mg/L) and potash (up to 9.43 mg/L) solubilization. Excluding the antagonistic <i>B. tequilensis</i>, four consortia were developed.

Blend 2 (<i>B. amyloliquefaciens</i>–<i>B. subtilis</i>–<i>B. licheniformis</i>) exhibited the highest heavy metal resilience, tolerating lead up to 1000 mg/L. Crucially, <i>B. haynesii</i> and <i>B. licheniformis</i> actively degraded the organophosphate malathion. LC–MS/MS verified biotransformation, mapping the metabolic breakdown into malathion monocarboxylic acid (MMC), and malathion dicarboxylic acid (MDC). This study presents the first official report of breakdown of malathion by <i>B. haynesii</i>.

The developed multi-strain Bacillus consortia show promising functional advantages over single-strain inoculants, providing a highly effective, multifaceted strategy for sustainable agriculture and environmental bioremediation.</p>