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

Abstract

Crude oil pollution can decrease the biodiversity in marine environment. The Persian Gulf in Iran is an ecosystem rich in marine organisms that can be effective in the degradation of crude oil. This study aimed to screening of bacterial strains to degrade crude oil from the intestinal microbial flora of Mudskippers fish from the Persian Gulf. Identification of collected fish samples distinguished four diverse genera that Periophthalmus waltoni was the most common. Next, biochemical and molecular identification of isolated bacteria was performed. Some biochemical tests such as catalase, oxidase, motility were done. Molecular identification was performed by polymerase chain reaction using general primers. Finally, the ability to degradation of crude oil by bacterial isolates was investigated by 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 degradation of crude oil (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 decrease the biodiversity in the intestinal microbial flora of these fish. The isolated bacteria can be able to degrade crude oil and help degraded this type of pollution in aquatic ecosystems. In the future by application of these bacteria the crude oil pollution in the Persian Gulf can be better managed and decreased.