title: Potential Environmental Factors Affecting Oil-Degrading Bacterial Populations in Deep and Surface Waters of the Northern Gulf of Mexico.
abstract: Understanding bacterial community dynamics as a result of an oil spill is important for predicting the fate of oil released to the environment and developing bioremediation strategies in the Gulf of Mexico. In this study, we aimed to elucidate the roles of temperature, water chemistry (nutrients), and initial bacterial community in selecting oil degraders through a series of incubation experiments. Surface (2 m) and bottom (1537 m) waters, collected near the Deepwater Horizon site, were amended with 200 ppm light Louisiana sweet crude oil and bacterial inoculums from surface or bottom water, and incubated at 4 or 24°C for 50 days. Bacterial community and residual oil were analyzed by pyrosequencing and gas chromatography-mass spectrometry (GC-MS), respectively. The results showed that temperature played a key role in selecting oil-degrading bacteria. Incubation at 4°C favored the development ofCycloclasticus, Pseudoalteromonas,Sulfitobacter, andReinekea, while 24°C incubations enhancedOleibacter, Thalassobius, Phaeobacter, and Roseobacter.Water chemistry and the initial community also had potential roles in the development of hydrocarbon-degrading bacterial communities.Pseudoalteromonas,Oleibacter, andWinogradskyelladeveloped well in the nutrient-enriched bottom water, whileReinekeaandThalassobiuswere favored by low-nutrient surface water. We revealed that the combination of 4°C, crude oil and bottom inoculum was a key factor for the growth ofCycloclasticus, while the combination of surface inoculum and bottom water chemistry was important for the growth ofPseudoalteromonas. Moreover, regardless of the source of inoculum, bottom water at 24°C was a favorable condition forOleibacter.Redundancy analysis further showed that temperature and initial community explained 57 and 19% of the variation observed, while oil and water chemistry contributed 14 and 10%, respectively. Overall, this study revealed the relative roles of temperature, water chemistry, and initial bacterial community in selecting oil degraders and regulating their evolution in the northern Gulf of Mexico.
authors.affiliation: Marine Science Institute, The University of Texas at Austin, Port Aransas TX, USA.
authors.forename: Jiqing
authors.initials: J
authors.lastname: Liu
authors.affiliation: Marine Science Institute, The University of Texas at Austin, Port Aransas TX, USA.
authors.forename: Hernando P
authors.initials: HP
authors.lastname: Bacosa
authors.affiliation: Marine Science Institute, The University of Texas at Austin, Port Aransas TX, USA.
authors.forename: Zhanfei
authors.initials: Z
authors.lastname: Liu
keywords: Deepwater Horizon oil spill; Gulf of Mexico; bacterial community; light Louisiana sweet crude oil; nutrients; oil-degrading bacteria; petroleum hydrocarbons; temperature