Concern about increasing incidents of petroleum hydrocarbon spills and spillage into different marine environments is rising day by day due to enhanced human activities in marine water. The toxic compounds of spilled petroleum hydrocarbon in marine water lead to the immediate death of numerous marine organisms as well as initiate various vicious biogeochemical cycles in the marine environment resulting in prolonged toxic impacts on the marine environment. Recently, many sophisticated techniques, including physical methods, chemical methods, and biological methods, have been developed and adopted for the treatment of marine environments polluted with petroleum compounds. However, biological treatment is one of the most promising methods in this field by which microorganisms such as bacteria, fungi, and algae are used for biodegradation of pollutants such as the spilled petroleum hydrocarbon into neutralized or eco-friendly compounds. This review has been focused on different aspects of the pollution of the marine ecosystem by oil, mainly Petroleum hydrocarbons, the fate of spilled oil in marine environments and the role of microbial communities in it, as well as various techniques, especially the bioremediation and biodegradation of spilled oil including the factors affecting the capacity of techniques. Moreover, some future aspects of research in the field of biodegradation and bioremediation of spilled oil have been proposed.

In marine environments where biofouling occurs and has an impact on the maritime economy and environment, compounds that inhibit the attachment, growth and survival of microorganisms in a biofilm complex as well as settlement of larvae are considered potential antifouling compounds. In this study, the extracellular metabolites from two surface- associated bacteria isolated from soft coral and macroalga were evaluated for antibiofilm and antisettlement activity. The bacteria were identified using 16S rRNA gene sequencing, and the culture supernatant extract of each strain was evaluated for antibiofilm activity. The compounds present in the extracts were analysed using GC-MS. The two bacterial strains were identified as Bacillus licheniformis MBR1 and Vibrio alginolyticus MBR4 for the isolates from soft coral and macroalgae, respectively. The extracts inhibited the growth of biofilm-forming bacteria, biofilm formation and barnacle larval settlement. The GC-MS analysis of the extract detected the presence of compounds such as tetrapentacontane, octadecanoic acid, 2,3-dihydroxypropyl ester, hexadecanoic acid, 2-hydroxy1-(hydroxymethyl) ethyl ester and 17-pentatriacontene. The results of the study show that extracellular metabolites of the bacteria associated with marine organisms could be used as natural antifouling compounds to control biofouling.

The halophilic consortia were enriched from water samples of Abhor, Red Sea, Jeddah, Saudi Arabia for the degradation of phenanthrene, fluorene, hexadecane, pyrene, and treatment of automobile service station wastewater under saline conditions (4%). Complete degradation of phenanthrene and fluorene was recorded up to a concentration of 500 mg.L-1 in 12 days, when the concentration was raised to 800 mg.L-1, the percentage of degradation of the two compounds was recorded by 84 and 90% within 14 days, while when the concentration increased to 1000 mg.L-1, a significant decline was recorded. Pyrene degradation was studied under saline conditions, where it recorded a degradation rate of 92 and 81% at a concentration of 50 and 100 mg.L-1 in 10 and 12 days, respectively, while when increasing the concentration, a severe decrease in the percentage of degradation was recorded that reached 57 and 44% at concentration 200 and 300 mg.L-1, respectively .Hexadecane recorded complete degradation at a concentration of 0.5 and 1%, within 4 and 6 days, respectively, while at a concentration of 1.5%, the rate of deterioration was 88% in 10 days. Record 93% removal of COD in CSTR within 40th day, when treatment of automobile service station wastewater with halophilic bacterial consortia. The existing bacterial strains were classified as potentially responsible for petroleum hydrocarbon degradation and treatment of automobile service station wastewater such as Ochrobactrum, Propionispira, Martelella, Bacillus, Marinobacter, and Azospira. The present study recommends that the hydrophilic consortia can be used in the treatment of automobile service station wastewater under saline conditions.