Characterization and Biotechnological Potential of Hydrocarbon-Degrading Consortia from Surface and Deep Waters of the Eastern Mediterranean Sea.

The structure and degradation capacity of hydrocarbon-degrading consortia from surface and deep waters of the Eastern Mediterranean Sea were studied in time-series experiments. Microcosms were set up at in situ temperatures, 25oC and 14oC for Surface and Deep, respectively and crude oil as the sole source of carbon and sampled after 6, 12, 18 and 24 days. The Deep consortium was additionally investigated at 25oC to allow direct comparison of degradation rates to the Surface consortium. In total, ~50% of alkanes and ~15% of PAHs were degraded in all treatments by day 24. Approximately ~95% of the total biodegradation took place within 6 days by the Deep consortium regardless of temperature, whereas comparable levels of degradation were reached by day 12 in the Surface25 treatment. Both consortia were dominated by well-known hydrocarbon-degrading taxa. Thalassospira, Halomonas and Idiomarina were differentially abundant in the Surface consortium. Temperature played a significant role in shaping the Deep consortia communities with Pseudomonas and Pseudoalteromonas dominating at 25oC and Alcanivorax at 14oC, where the highest diversity was observed. Overall, the Deep consortium showed higher efficiency for hydrocarbon degradation within the first - and more critical in the case of oil spills - week following contamination.