Isolation, Identification and Use of Bacterial Strain Ochrobactrum intermedium PDB-3 for Degradation of the Pesticide Chlorpyrifos

Abstract

One of the serious modern environmental problems is pollution caused by highly toxic pesticides. Only small amounts of applied pesticides reach their target, and the rest ends up in soil and water. Chlorpyrifos is a toxic, broad-spectrum organophosphate insecticide. In humans, chlorpyrifos inhibits acetylcholinesterase (AChE) in the peripheral and central nervous system, and particularly in children, small amounts of this pesticide cause neurotoxic damage. As the toxic effects of chlorpyrifos and its persistence in the environment require its removal from contaminated sites, it is essential to study the biological diversity of chlorpyrifos-degrading microorganisms. In this study, we sought to determine the chlorpyrifos-degrading ability of the bacterial strain Ochrobactrum intermedium PDB-3. This strain was isolated from soil contaminated with various pesticides and identified as PDB-3 based on morpho-cultural characteristics, MALDI-TOF MS, and 16S rRNA. Studies were conducted for 30 days in sterile soils containing initial concentrations of 50, 75, 100, and 125 mg/kg of chlorpyrifos. To determine the degradation of chlorpyrifos, a liquid culture of the strain was added to the soil at three optical densities: 0, and after 24 and 48 h (OD = 0.03, 0.2 and 0.32). Using GX-MS, we determined that chlorpyrifos was converted to 3,5,6-trichloro-2-pyridinol (TCP). We also found that with increasing optical density, rapid degradation of the initial concentration of chlorpyrifos occurred. Sterile soil without strain PDB-3 was used as a control sample.