Abstract:
Petroleum polycyclic aromatic hydrocarbons (PAH) are health risks to human and increases the environmental concern. Therefore, removal of these compounds from the environment is a necessity for ensuring human health. In this study two gram negative bacterial strains, KKU-B1 and KKU-B2, exhibiting ability for petroleum PAHs degradation were isolated by enrichment techniques from oil-contaminated soil. The isolates were genetically identified based on the nucleotide sequence of 16S rRNA gene and phylogenetic analysis as Ochrobactrum anthropi and Sphingomonas paucimobilis respectively. The efficiency of the two isolates KKU-B1 and KKU-B2 on naphthalene and phenanthrene degradation was individually evaluated by their extensive growth on minimal salt medium supplemented with these PAH compounds. Strain KKU-B1 exhibited best growth (0.321 OD600) when exposed to 100mg/l of naphthalene for 7 days and could utilize up to 250 mg/l of this compound. The least growth of 0.209 (OD600) was observed by this strain at 250 mg/l phenanthrene while the highest was 0.288 at 100 mg/l of phenanthrene. Similarly, the highest growth of 0.413 (OD 600) was recorded by strain KKU-B2 treated with 100mg/l of naphthalene. On the other hand the least growth of strain KKU-B2 was 0.235 when treated with 250mg/l of phananthrene, while the highest was 0.246 at 100mg/l of phenanthrene. Our results demonstrated that the two isolated strains KKU-B1 and KKU-B2 could be recommended for PAHs removal from the environment.