Biodegradation of chlorpyrifos by bacterial strains isolated from Lebanese soil and its association with plant growth improvement

Abstract

Chlorpyrifos poses a danger to the environment as a result of its toxicity and endurance in soil and water. Bioremediation of pesticide-polluted soils is one of the most promising approaches for removing contaminants from the environment. This study aimed to isolate and identify chlorpyrifos-degrading bacterial strains and test their biodegradation capabilities and their roles in plant growth. The 16S rDNA gene sequencing identified the two efficient chlorpyrifos-degrading bacterial strains as Stenotrophomonas maltophilia (RS1) and Acinetobacter calcoaceticus (RS3), which significantly (p < 0.01) degraded 71.3% and 73.5% of chlorpyrifos in the liquid medium, respectively, compared to 80% degradation (p < 0.01) when cultured as a consortium within 48 h. The bioremediation of artificially chlorpyrifos-contaminated soils varied between 84.4% and 90.11% (p < 0.01), depending on the used bacterium and soil sterilization status. Furthermore, the enzymes embroiled in the degradation mechanism were sprinkled all over the cells but with different portions. Experiments on plant growth revealed that chlorpyrifos hurt lettuce growth. The presence of RS1 and RS3, on the other hand, demonstrated considerable lettuce growth-enhancing traits in terms of germination percentages, shoot and root lengths and weights. Our isolates could be promising candidates in the bioremediation of chlorpyrifos-contaminated sites in conjunction with their contribution as biofertilizers.