Hydrocarbon-utilizing bacteria associated with biofouling materials from offshore waters of the Arabian Gulf

Biofouling materials from 30 offshore substrates in eight sites along the Kuwaiti coast harbored 3 × 106–28 × 106 bacterial cells g−1, as counted microscopically. Using culture-based methods, 7 × 104–4.1 × 106 colony forming units (CFU's) were counted on a nitrogen-containing mineral medium with oil vapor as a sole carbon source. According to their 16S rDNA sequences, those bacteria were affiliated with species belonging to the genera Alcanivorax, Dietzia, Gordonia, Hoyosella, Kocuria, Marinobacter, Micrococcus, Mycobacterium, Planococcus, Planomicrobium, Pseudoalteromonas, Salinivibrio, and Vibrio. Similar numbers of CFUs appeared on the nitrogen-free mineral media; the predominant species were affiliated with most of the genera recorded above, in addition to Agrobacterium, Labrenzia, Microbacterium, Nitratireductor, Pseudomonas, and Rhodococcus. Isolates of these bacteria grew on a wide range of individual alkanes, phenanthrene, naphthalene, and biphenyl as sole carbon sources. Quantitative determinations showed that individual bacteria could attenuate crude oil, pure n-octadecane, and pure naphthalene in batch cultures. Also microbial consortia associated with fresh environmental samples attenuated oil in batch cultures in the presence and absence of NaNO3. It was concluded that bacteria associated with biofouling materials probably contribute to hydrocarbon bioremediation in the Arabian Gulf.

► Marine biofouling materials harbored hydrocarbon-utilizing bacteria.
► Predominant genera: Alcanivorax, Dietzia, Gordonia, Hoyosella, Pseudoalteromonas.
► Most of the isolates were also diazotrophic.
► Inoculation with biofouling materials attenuated hydrocarbons in culture.