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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

Changes in bacterial density during the incubation in the dark and light conditions. The values and error bars represents mean and standard deviation of two replicates, respectively. The bacterial cells were enumerated via flow cytometry.
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Figure 1: Changes in bacterial density during the incubation in the dark and light conditions. The values and error bars represents mean and standard deviation of two replicates, respectively. The bacterial cells were enumerated via flow cytometry.

Mentions: During the first 5 days, only the treatments containing Corexit showed an increase in bacterial density (Figure 1), while those containing crude oil alone showed no growth. Between 5 and 20 days, cell densities in all samples with added substrates increased linearly, and cell numbers peaked at 20 days for most treatments. After 20 days, treatment with dispersant alone decreased abruptly (about 15-fold), while those with oil either increased slightly or plateaued. Throughout the whole incubation period, there were no marked changes of cell density in either light or dark control.


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

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

Changes in bacterial density during the incubation in the dark and light conditions. The values and error bars represents mean and standard deviation of two replicates, respectively. The bacterial cells were enumerated via flow cytometry.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 1: Changes in bacterial density during the incubation in the dark and light conditions. The values and error bars represents mean and standard deviation of two replicates, respectively. The bacterial cells were enumerated via flow cytometry.
Mentions: During the first 5 days, only the treatments containing Corexit showed an increase in bacterial density (Figure 1), while those containing crude oil alone showed no growth. Between 5 and 20 days, cell densities in all samples with added substrates increased linearly, and cell numbers peaked at 20 days for most treatments. After 20 days, treatment with dispersant alone decreased abruptly (about 15-fold), while those with oil either increased slightly or plateaued. Throughout the whole incubation period, there were no marked changes of cell density in either light or dark control.

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