Screening of crude-oil degrading bacteria from gastrointestinal of gobiiformes collected at the Persian gulf: biotechnological importance for remediation of the polluted marine environment.

Crude oil pollution can decrease the biodiversity in the marine environment. The Persian Gulf in Iran is an ecosystem rich in marine organisms that can effectively degrade crude oil. This study aimed to screen bacterial strains to degrade crude oil from the intestinal microbial flora of Mudskippers fish from the Persian Gulf. The identification of collected fish samples distinguished four diverse genera. Periophthalmus waltoni was the most common. Next, biochemical and molecular identification of isolated bacteria was performed. Some biochemical tests, such as catalase, oxidase, and motility, were done. Molecular identification was performed by polymerase chain reaction using general primers. Finally, the ability of bacterial isolates to degrade crude oil was investigated using spectrophotometric, gravimetric, gas chromatography, and FTIR methods. Bacteria identified in this study include Marinobacter hydrocarbonoclasticus, Pseudomonas aestusnigri, Thalassospira permensis, Microbacterium esteraromaticu, Oceanimonas sp, Halomonas Salaria, Halomonas beimenensis, Cobetia marina, Tenacibaculum discolor and Shewanella chilikensis. Halomonas salaria had the highest growth rate (OD= 1.6) and crude oil degradation (90%) among the studied strains. The results of our studies on five strains of T. permensis, S. chilikensis, M. hydrocarbonoclasticus, and Oceanimonas in concentrations of 1, 2.5, 4, 5.5, and 7 g/l crude oil show that with increasing concentration, crude oil reduces the ability of the strains to degradation (decrease degradation from 90 % to 20 %). Other studies have been conducted to recognize fish as an indicator of oil pollution. Still, the results of this research confirmed that crude oil pollution decreases the biodiversity in the intestinal microbial flora of these fish. The isolated bacteria can degrade crude oil and help degrade this pollution in aquatic ecosystems. By applying these bacteria, crude oil pollution in the Persian Gulf can be better managed and decreased. [ABSTRACT FROM AUTHOR]