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 of Cycloclasticus, Pseudoalteromonas, Sulfitobacter, and Reinekea, while 24°C incubations enhanced Oleibacter, Thalassobius, Phaeobacter, and Roseobacter. Water chemistry and the initial community also had potential roles in the development of hydrocarbon-degrading bacterial communities. Pseudoalteromonas, Oleibacter, and Winogradskyella developed well in the nutrient-enriched bottom water, while Reinekea and Thalassobius were 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 of Cycloclasticus, while the combination of surface inoculum and bottom water chemistry was important for the growth of Pseudoalteromonas. Moreover, regardless of the source of inoculum, bottom water at 24°C was a favorable condition for Oleibacter. 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.

Response of marine bacteria to oil contamination and to high pressure and low temperature deep sea conditions

“…Moreover, different Gammaproteobacteria (such as Pseudoalteromonas and Alteromonas , whose relative abundances increased in the oil‐contaminated microcosms incubated at 22°C and at 0.1 MPa) and Alphaproteobacteria (such as Sulfitobacter , whose relative abundance increased in oil‐contaminated microcosms incubated at 4°C and at 0.1 MPa) have already been described as petroleum degraders (Gutierrez et al., ; Hazen et al., ; Jung et al., ; Meng et al., ), which may explain the enrichment of these bacteria in oil‐contaminated microcosms. Similarly, Liu, Bacosa, and Liu () demonstrated that temperature is quite important for the selection of oil‐degrading bacteria, as they found that 4°C favored the development of Cycloclasticus , Pseudoalteromonas , Sulfitobacter (as observed here), and Reinekea , while 24°C incubations enhanced Oleibacter , Thalassobius , Phaeobacter, and Roseobacter from water samples collected near the Deepwater Horizon site.…”

“…Similarly, Liu, Bacosa, and Liu (2017) The relative abundance of the OTUs for depressurized and then repressurized microcosms varied compared to those at the beginning of the experiment and also those pressurized continuously for 40 days. Abrupt changes in pressure can alter bacterial physiology and often lead to cellular lysis (Koyama, Kobayashi, Inoue, Miwa, & Aizawa, 2005).…”

Response of microbial communities to oil spill in the Gulf of Mexico: A review

“…The introduction of oil into a marine ecosystem makes considerable excess of carbon available in the development of microorganisms (Prince et al, 2003). However, unavailability of nutrients (nitrogen and phosphorus) is able to lessen the development of microbes and hence oil degradation (Liu et al, 2017). In an attempt to promote oil degradation on diverse coastlines (including the Arctic), fertilizers containing available nitrogen and phosphorus were added (Prince et al, 2003).…”

Pressure and temperature effects on deep‐sea hydrocarbon‐degrading microbial communities in subarctic sediments

“…Oil degradation generally proceeds faster at mesophilic T. However, low T-adapted microbial communities are capable of rapid oil degradation (Coulon, McKew, Mark Osborn, McGenity, & Timmis, 2007;Ferguson, Gontikaki, Anderson, & Witte, 2017;Techtmann et al, 2017;Venosa & Holder, 2007). In some cases, the degradation of polycyclic aromatic hydrocarbons by deepwater microbial communities has been reported to be higher at low T (4-5°C) compared to high T incubations (20-24°C) (Campo, Venosa, & Suidan, 2013;Liu, Bacosa, & Liu, 2017). The T dependence of cellular processes can vary greatly and may be confounded by other environmental parameters, such as hydrostatic P (Fumiyoshi, 2007;López-Urrutia et al, 2006).…”