Isolation and identification a naphthalene degrading bacteria from Nayband Bay and optimizing the biodegradation conditions

In order to isolate and to identify naphthalene degrading bacteria from Nayband Bay sediments and to optimize biodegradation efficiency using the most effective isolated strain, surface sediment samples were collected from Nayband Bay mangrove forests. Obtained samples were then cultured on mineral salts medium (MSM) containing naphthalene as a sole carbon source. At the end of the enrichment, three bacterial strains in the consortium were isolated by spreading the 10-fold serially diluted consortium on nutrient agar plates. Naphthalene biodegradating efficiency of the isolated strains was monitored in two culture media: 1-MSM + naphthalene, 2-MSM + naphthalene + Tween-80. The ability of bacterial isolates to degrade naphthalene was studied by using gas chromatography. Among the isolated strains, SBU3 was found to be more efficient, degrading naphthalene in presence and absence of Tween-80, 60.45% and 39.30% respectively. This strain was identified by 16s rDNA gene sequence and results showed that it has 99% similarity to Marinobacter aquaeolei. The Optimum pH and C/N molar ratio for the biodegradation of naphthalene were studied in presence of 1% tween-80, results show that the pH 7.5 and C/N ratio of 100:10 were the optimum conditions and more than 85% of naphthalene removed within 7 days. Furthermore, the biodegradation kinetics of naphthalene corresponded with the first-order rate model.