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Natural Sunlight Shapes Crude Oil-Degrading Bacterial Communities in Northern Gulf of Mexico Surface Waters.

Bacosa HP, Liu Z, Erdner DL - Front Microbiol (2015)

Bottom Line: Our results showed that, for treatments with oil and/or Corexit, sunlight significantly reduced bacterial diversity and evenness and was a key driver of shifts in bacterial community structure.In samples containing oil or dispersant, sunlight greatly reduced abundance of the Cyanobacterium Synechococcus but increased the relative abundances of Alteromonas, Marinobacter, Labrenzia, Sandarakinotalea, Bartonella, and Halomonas.For the first time, we demonstrated the effects of light in structuring microbial communities in water with oil and/or Corexit.

View Article: PubMed Central - PubMed

Affiliation: Marine Science Institute, The University of Texas at Austin Port Aransas, TX, USA.

ABSTRACT
Following the Deepwater Horizon (DWH) spill in 2010, an enormous amount of oil was observed in the deep and surface waters of the northern Gulf of Mexico. Surface waters are characterized by intense sunlight and high temperature during summer. While the oil-degrading bacterial communities in the deep-sea plume have been widely investigated, the effect of natural sunlight on those in oil polluted surface waters remains unexplored to date. In this study, we incubated surface water from the DWH site with amendments of crude oil, Corexit dispersant, or both for 36 days under natural sunlight in the northern Gulf of Mexico. The bacterial community was analyzed over time for total abundance, density of alkane and polycyclic aromatic hydrocarbon degraders, and community composition via pyrosequencing. Our results showed that, for treatments with oil and/or Corexit, sunlight significantly reduced bacterial diversity and evenness and was a key driver of shifts in bacterial community structure. In samples containing oil or dispersant, sunlight greatly reduced abundance of the Cyanobacterium Synechococcus but increased the relative abundances of Alteromonas, Marinobacter, Labrenzia, Sandarakinotalea, Bartonella, and Halomonas. Dark samples with oil were represented by members of Thalassobius, Winogradskyella, Alcanivorax, Formosa, Pseudomonas, Eubacterium, Erythrobacter, Natronocella, and Coxiella. Both oil and Corexit inhibited the Candidatus Pelagibacter with or without sunlight exposure. For the first time, we demonstrated the effects of light in structuring microbial communities in water with oil and/or Corexit. Overall, our findings improve understanding of oil pollution in surface water, and provide unequivocal evidence that sunlight is a key factor in determining bacterial community composition and dynamics in oil polluted marine waters.

No MeSH data available.


Related in: MedlinePlus

Abundances of bacteria at genus level in seawater alone, seawater with dispersant Corexit, crude oil, and both oil and dispersant incubated under the dark and light conditions for 36 days. Only abundances greater than 5% in at least one of the samples are shown. (A)Flavobacteria, (B)Gammaproteobacteria, (C)Alphaproteobacteria, (D) Other bacteria. The numbers indicate days of incubation.
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Figure 6: Abundances of bacteria at genus level in seawater alone, seawater with dispersant Corexit, crude oil, and both oil and dispersant incubated under the dark and light conditions for 36 days. Only abundances greater than 5% in at least one of the samples are shown. (A)Flavobacteria, (B)Gammaproteobacteria, (C)Alphaproteobacteria, (D) Other bacteria. The numbers indicate days of incubation.

Mentions: Among the Flavobacteria, Sandarakinotalea became dominant in light treatments with oil after 27 days and in light-dispersant at 20 days (8–42%), while dark incubation favored Winogradskyella (5–25%) and Formosa (4–10%) in treatments with dispersant throughout the incubation period (Figure 6A). Of the members of Gammaproteobacteria, Alteromonas was represented in both light and dark treatments (Figure 6B). However, it dominated at the first 10 days in light treatments with amended substrates, constituting up to 60–80% of the total bacterial community. The abundance of Marinobacter (7–50%) was also greatly enhanced in light treatments with oil and oil+dispersant, and Halomonas (9–20%) in oil+dispersant. Coxiella predominated in later stage (27 and/or 36 days) of the dark-substrate treatments (10–55%). Alcanivorax, a known alkane degrader, was abundant in dark treatments with oil between 5 and 20 days (up to 30%), whereas in oil+dispersant samples, it increased between 20 and 36 days, In the light, Alcanivorax only became abundant at 36 days. Natronocella and Pseudomonas were also associated with dark incubation with oil.


Natural Sunlight Shapes Crude Oil-Degrading Bacterial Communities in Northern Gulf of Mexico Surface Waters.

Bacosa HP, Liu Z, Erdner DL - Front Microbiol (2015)

Abundances of bacteria at genus level in seawater alone, seawater with dispersant Corexit, crude oil, and both oil and dispersant incubated under the dark and light conditions for 36 days. Only abundances greater than 5% in at least one of the samples are shown. (A)Flavobacteria, (B)Gammaproteobacteria, (C)Alphaproteobacteria, (D) Other bacteria. The numbers indicate days of incubation.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4664628&req=5

Figure 6: Abundances of bacteria at genus level in seawater alone, seawater with dispersant Corexit, crude oil, and both oil and dispersant incubated under the dark and light conditions for 36 days. Only abundances greater than 5% in at least one of the samples are shown. (A)Flavobacteria, (B)Gammaproteobacteria, (C)Alphaproteobacteria, (D) Other bacteria. The numbers indicate days of incubation.
Mentions: Among the Flavobacteria, Sandarakinotalea became dominant in light treatments with oil after 27 days and in light-dispersant at 20 days (8–42%), while dark incubation favored Winogradskyella (5–25%) and Formosa (4–10%) in treatments with dispersant throughout the incubation period (Figure 6A). Of the members of Gammaproteobacteria, Alteromonas was represented in both light and dark treatments (Figure 6B). However, it dominated at the first 10 days in light treatments with amended substrates, constituting up to 60–80% of the total bacterial community. The abundance of Marinobacter (7–50%) was also greatly enhanced in light treatments with oil and oil+dispersant, and Halomonas (9–20%) in oil+dispersant. Coxiella predominated in later stage (27 and/or 36 days) of the dark-substrate treatments (10–55%). Alcanivorax, a known alkane degrader, was abundant in dark treatments with oil between 5 and 20 days (up to 30%), whereas in oil+dispersant samples, it increased between 20 and 36 days, In the light, Alcanivorax only became abundant at 36 days. Natronocella and Pseudomonas were also associated with dark incubation with oil.

Bottom Line: Our results showed that, for treatments with oil and/or Corexit, sunlight significantly reduced bacterial diversity and evenness and was a key driver of shifts in bacterial community structure.In samples containing oil or dispersant, sunlight greatly reduced abundance of the Cyanobacterium Synechococcus but increased the relative abundances of Alteromonas, Marinobacter, Labrenzia, Sandarakinotalea, Bartonella, and Halomonas.For the first time, we demonstrated the effects of light in structuring microbial communities in water with oil and/or Corexit.

View Article: PubMed Central - PubMed

Affiliation: Marine Science Institute, The University of Texas at Austin Port Aransas, TX, USA.

ABSTRACT
Following the Deepwater Horizon (DWH) spill in 2010, an enormous amount of oil was observed in the deep and surface waters of the northern Gulf of Mexico. Surface waters are characterized by intense sunlight and high temperature during summer. While the oil-degrading bacterial communities in the deep-sea plume have been widely investigated, the effect of natural sunlight on those in oil polluted surface waters remains unexplored to date. In this study, we incubated surface water from the DWH site with amendments of crude oil, Corexit dispersant, or both for 36 days under natural sunlight in the northern Gulf of Mexico. The bacterial community was analyzed over time for total abundance, density of alkane and polycyclic aromatic hydrocarbon degraders, and community composition via pyrosequencing. Our results showed that, for treatments with oil and/or Corexit, sunlight significantly reduced bacterial diversity and evenness and was a key driver of shifts in bacterial community structure. In samples containing oil or dispersant, sunlight greatly reduced abundance of the Cyanobacterium Synechococcus but increased the relative abundances of Alteromonas, Marinobacter, Labrenzia, Sandarakinotalea, Bartonella, and Halomonas. Dark samples with oil were represented by members of Thalassobius, Winogradskyella, Alcanivorax, Formosa, Pseudomonas, Eubacterium, Erythrobacter, Natronocella, and Coxiella. Both oil and Corexit inhibited the Candidatus Pelagibacter with or without sunlight exposure. For the first time, we demonstrated the effects of light in structuring microbial communities in water with oil and/or Corexit. Overall, our findings improve understanding of oil pollution in surface water, and provide unequivocal evidence that sunlight is a key factor in determining bacterial community composition and dynamics in oil polluted marine waters.

No MeSH data available.


Related in: MedlinePlus