Screening and Identification of Naphthalene Degrading Bacteria From the Intestines of Some Fishes in the Geo-marine Sites of The Persian Gulf

Abstract Naphthalene is an aromatic compound consisting of two benzene rings, which is a very toxic substance. In this research, for isolation of naphthalene-degrading bacteria, samples were taken from the intestines of Argyrops spinifer, Protonibea diacanthus, and Otolithes ruber fishes. After screening, it was found that 9 strains have the ability to grow and degrade naphthalene at an initial concentration of 200 ppm. Then, characteristics such as emulsifying activity (E24) were investigated. After molecular identification, the results showed that this strain (CD-2) belonged to the genus Pseudomonas sp. with 96% similarity. Also, strains CD-2 (Pseudomonas), DD-2, and DD-3 had better performance in terms of naphthalene degradation. The optimization results show that increasing the concentration of naphthalene, in the absence of glucose and in the presence of glucose, led to a decrease in its removal percentage by bacteria. In the absence of glucose, increasing peptone increased the removal percentage of naphthalene. In the presence of glucose, to a certain concentration, increasing peptone improved the removal efficiency. In the absence of glucose, increasing peptone increased the removal percentage of naphthalene. In this research, it was found that the highest diversity of naphthalene-degrading bacteria is related to A. spinifer, P. diacanthus, and O. ruber fishes.