Degradation of anthracene and phenanthrene by strain Streptomyces sp. M-1 and its application in the treatment of PAHs-contaminated water.

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants with mutagenicity, carcinogenicity and teratogenicity, widely distributed in the environment. Effective biodegradation of PAHs is highly required, especially in wastewater. An efficient PAHs degrading strain Streptomyces sp. M-1 was isolated from polluted kerosene. The degradation capacity of anthracene and phenanthrene was evaluated under various PAHs concentrations, pH, and temperatures by M-1. To find the degradation pathways, the key intermediates were detected by mass spectrometry and the enzyme-encoding genes were analyzed by many bioinformatics tools. Furthermore, the potential of the strain for bioremediation in PAH-contaminated water was evaluated. The results showed that the maximal degradation rate of anthracene and phenanthrene reached 93.14% (100 mg L-1, 7 days) and 49.25% (50 mg L-1, 7 days), respectively. Their average degradation rate increased within the concentration of 50-800 mg L-1 and reached 2.72 mg d-1 for anthracene and 1.28 mg d-1 for phenanthrene at 800 mg L-1. M-1 exhibited high and stable anthracene degradation rate under tested pH and temperatures, and high phenanthrene degradation under tested pH and higher temperatures. Based on the analysis of both intermediates and enzyme-encoding genes, it is proposed that anthracene undergoes degradation via the phthalic acid pathway, while phenanthrene follows the salicylic acid pathway. Finally, 98.98% degradation of anthracene and 72.77% degradation of phenanthrene in water was realized over 14 days. We thus propose that Streptomyces sp. M-1 is an effective degrader for bioremediation of PAHs pollution.