BIODEGRADATION OF SOME PAHs BY A LOCALLY-ISOLATED STRAIN OF ACTINOMYCETES

Abstract

Samples from the River Nile, the Mediterranean, and the Red Sea were chemically and microbiologically evaluated. The chemical analysis proved that cations and anions concentrations were of higher values in seawater samples in comparison with those of the Nile water. The microbiological analysis showed that Cairo University Nile Bus Station samples (GCB-19) recorded the increased total viable microbial counts (1.6x10 4 CFU/ml). Total coliforms highest counts were analyzed in GCB-19 samples (110 cells/ml), whereas fecal coliforms highest counts (15 cells/ml) were recorded in Cairo University Nile Bus Station samples (GCB-17) and (GCB-19). PAHs were determined in the collected samples using GC/MS. Seawater samples had increased concentrations of PAHs in comparison with River Nile water ones. Fluorene was the major PAH in all water samples, for it ranged from 25 to 50 ppt. An actinomycetes isolate from the collected samples underwent molecular identification through the pair-wise alignment of its 16S rDNA sequence with sequences in the database. It was indicated that it was identical to Streptomyces macrosporeus with a 98.65% homology sequence. Streptomyces macrosporeus was examined for degradation efficiency of 0.1, 0.05, 0.025, and 0.0125 ppm of PAHs standard mix and 200 ppm of naphthalene, fluorene, and anthracene, individually for 5 days/37 o C. It degraded all the detectable concentrations of the chemicals in the PAHs standard mix except for some non-degradable traces of naphthalene. Furthermore, it degraded naphthalene, fluorene and anthracene individually with a percentage of 99.99%, 94.88%, and 96.33%, respectively. Thus, the results of the current study reflected the biodegradation capability of Streptomyces macrosporeus for different PAHs.