ACINETOBACTER SPP. AND STENOTROPHOMONAS ACIDAMINIPHILA STRAIN PARS1396 ISOLATED FROM LANDFILL SOIL AND INDUSTRIAL WASTEWATER AS POTENTIAL CANDIDATES FOR PHENOL BIODEGRADATION

The aim of this study was to isolate phenol-degrading bacteria from highly contaminated environments with various pollutants, including painting factory wastewater and landfill soil, to investigate their capacity for phenol-degradation. Isolates were identified based on biochemical tests and 16s rDNA gene analysis.To detect the breakdown of phenol and the metabolites formed from its cleavage, high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) analyses were used. Polymerase chain reaction (PCR) analysis and colorimetric methods were applied to identify genes including catechol 1,2-dioxygenase (C1,2D), catechol 2,3-dioxygenase (C2,3D) and protocatechuate 3,4-dioxygenase (P3,4D) and their related enzymes activities. Four strains were isolated and identified as Acinetobacter sp. strain CASPIAN1396 (GenBank Accession number MH298648), Acinetobacter sp. strain PARS1396 (MH298615), Acinetobacter sp. strain SARAVAN1396 (MH298541), and Stenotrophomunas acidaminiphila strain MMDA2018 (MH298661). All isolates were able to degrade 0.4g/l of phenol down to levels below 0.08g/l after 72h at 30 degrees C and pH 7.2. The Acinetobacter spp. grew in the presence of up to 0.8g/l phenol, but the S. acidaminiphila strain PARS1396 was the sole strain that was able to grow at 1g/l concentration of phenol. The results showed that the C1,2O gene was detected in all isolates, but neither C2,3O or P3,4D gene sequences were found in any of them. The C1,2D gene was inducible in all isolates, and the strains degraded phenol via the ortho pathway. The use of S. acidaminiphila for phenol biodegradation could be promising because it can tolerate high concentrations of phenol and grows in severely contaminated environments.