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Enrichment and Identification of Phenanthrene-degrading Bacteria Isolated from the Oil-stained Engine Sediment in the Mangrove Swamps of Thailand

Polycyclic aromatic hydrocarbons (PAHs) are persistent pollutants that contaminate various environments. The biodegradation method conducted by bacteria is a promising alternative approach to remediate PAHs. Mangrove bacteria play a role in biogeochemical cycles and are able to degrade PAHs. The aims of this study included the enrichment, isolation, and characterization of phenanthrene (or tricyclic PAH)-degrading bacteria from some oil-stained engine sediments in a mangrove swamp in Rayong Province, Thailand. Ten isolated phenanthrenedegrading bacteria with a high ability for biodegradation were phenotypically and genetically identified. They are considered proteobacteria in the genera of Achromobacter, Comamonas, and Pseudomonas. The phenanthrene biodegradation results revealed that Pseudomonas sp. strain MP6-0207 could degrade phenanthrene 52.35 ± 0.28% of 100 mg/L of phenanthrene supplemented in saline Bushnell Haas Medium within 7 days. Its cells could adhere to the hydrophobic structure of phenanthrene with a BATH value of 45.17 ± 0.29% and produced biosurfactant to solubilize phenanthrene with E24 value of 32.33 ± 2.52%. The knowledge gained from this study offers a novel report on the isolation of phenanthrene-degrading bacteria from the mangrove swamp in Rayong Province, Thailand and could be used for future PAHs bioremediation in the contaminated sites.