Limits...
Effect of high pressure on hydrocarbon-degrading bacteria.

Schedler M, Hiessl R, Valladares Juárez AG, Gust G, Müller R - AMB Express (2014)

Bottom Line: However, above this pressure growth decreased and at 12 MPa or more no more growth was observed.Nevertheless, S. yanoikuyae continued to convert naphthalene at pressure >12 MPa, although at a lower rate than at 0.1 MPa.These results show that high pressure has a strong influence on the biodegradation of crude oil components and that, contrary to previous assumptions, the role of pressure cannot be discounted when estimating the biodegradation and ultimate fate of deep-sea oil releases such as the Deepwater Horizon event.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Technical Biocatalysis, Hamburg University of Technology, Hamburg 21073, Germany.

ABSTRACT
The blowout of the Deepwater Horizon in the Gulf of Mexico in 2010 occurred at a depth of 1500 m, corresponding to a hydrostatic pressure of 15 MPa. Up to now, knowledge about the impact of high pressure on oil-degrading bacteria has been scarce. To investigate how the biodegradation of crude oil and its components is influenced by high pressures, like those in deep-sea environments, hydrocarbon degradation and growth of two model strains were studied in high-pressure reactors. The alkane-degrading strain Rhodococcus qingshengii TUHH-12 grew well on n-hexadecane at 15 MPa at a rate of 0.16 h(-1), although slightly slower than at ambient pressure (0.36 h(-1)). In contrast, the growth of the aromatic hydrocarbon degrading strain Sphingobium yanoikuyae B1 was highly affected by elevated pressures. Pressures of up to 8.8 MPa had little effect on growth of this strain. However, above this pressure growth decreased and at 12 MPa or more no more growth was observed. Nevertheless, S. yanoikuyae continued to convert naphthalene at pressure >12 MPa, although at a lower rate than at 0.1 MPa. This suggests that certain metabolic functions of this bacterium were inhibited by pressure to a greater extent than the enzymes responsible for naphthalene degradation. These results show that high pressure has a strong influence on the biodegradation of crude oil components and that, contrary to previous assumptions, the role of pressure cannot be discounted when estimating the biodegradation and ultimate fate of deep-sea oil releases such as the Deepwater Horizon event.

No MeSH data available.


Related in: MedlinePlus

Degradation of n-hexadecane at 0.1 MPa vs. 15 MPa byR. qingshengiiTUHH-12. The CFUs were determined by plate counting and n-hexadecane concentrations were measured by gas chromatography–mass spectrometry. CFUs were determined in triplicate and standard deviations are shown. △ CFU at 0.1 MPa, ▲ CFU at 15 MPa, □ n-hexadecane concentration at 0.1 MPa, ■ n-hexadecane concentration at 15 MPa.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4230898&req=5

Figure 2: Degradation of n-hexadecane at 0.1 MPa vs. 15 MPa byR. qingshengiiTUHH-12. The CFUs were determined by plate counting and n-hexadecane concentrations were measured by gas chromatography–mass spectrometry. CFUs were determined in triplicate and standard deviations are shown. △ CFU at 0.1 MPa, ▲ CFU at 15 MPa, □ n-hexadecane concentration at 0.1 MPa, ■ n-hexadecane concentration at 15 MPa.

Mentions: R. qingshengii TUHH-12 was cultivated on n-hexadecane as the sole source of carbon and energy. R. qingshengii TUHH-12 was found to grow well and to mineralize this hydrocarbon at atmospheric pressure (0.1 MPa) as well as at high pressure (15 MPa). At 15 MPa the degradation and growth behaviour was slightly different from that at atmospheric pressure (Figure 2). In both cases, a lag phase of 16 to 17 h was followed by an exponential growth phase and a stationary phase starting after 43 to 44 h of incubation. However, the growth rate of R. qingshengii TUHH-12 in the exponential phase was 0.36 h−1 at ambient pressure, from 17 h to 43 h, compared to 0.16 h−1 at high pressure, from 16 h to 44 h. In the stationary phase a higher cell density was reached at 0.1 MPa than at 15 MPa. The rate of degradation of n-hexadecane was 0.035 mM/h at ambient pressure from 17 to 43 h, and 0.019 mM/h at high pressure, from 16 to 44 h. In control experiments without bacteria at 15 MPa the n-hexadecane also slowly decreased although with a much slower rate of 0.007 mM/h.


Effect of high pressure on hydrocarbon-degrading bacteria.

Schedler M, Hiessl R, Valladares Juárez AG, Gust G, Müller R - AMB Express (2014)

Degradation of n-hexadecane at 0.1 MPa vs. 15 MPa byR. qingshengiiTUHH-12. The CFUs were determined by plate counting and n-hexadecane concentrations were measured by gas chromatography–mass spectrometry. CFUs were determined in triplicate and standard deviations are shown. △ CFU at 0.1 MPa, ▲ CFU at 15 MPa, □ n-hexadecane concentration at 0.1 MPa, ■ n-hexadecane concentration at 15 MPa.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4230898&req=5

Figure 2: Degradation of n-hexadecane at 0.1 MPa vs. 15 MPa byR. qingshengiiTUHH-12. The CFUs were determined by plate counting and n-hexadecane concentrations were measured by gas chromatography–mass spectrometry. CFUs were determined in triplicate and standard deviations are shown. △ CFU at 0.1 MPa, ▲ CFU at 15 MPa, □ n-hexadecane concentration at 0.1 MPa, ■ n-hexadecane concentration at 15 MPa.
Mentions: R. qingshengii TUHH-12 was cultivated on n-hexadecane as the sole source of carbon and energy. R. qingshengii TUHH-12 was found to grow well and to mineralize this hydrocarbon at atmospheric pressure (0.1 MPa) as well as at high pressure (15 MPa). At 15 MPa the degradation and growth behaviour was slightly different from that at atmospheric pressure (Figure 2). In both cases, a lag phase of 16 to 17 h was followed by an exponential growth phase and a stationary phase starting after 43 to 44 h of incubation. However, the growth rate of R. qingshengii TUHH-12 in the exponential phase was 0.36 h−1 at ambient pressure, from 17 h to 43 h, compared to 0.16 h−1 at high pressure, from 16 h to 44 h. In the stationary phase a higher cell density was reached at 0.1 MPa than at 15 MPa. The rate of degradation of n-hexadecane was 0.035 mM/h at ambient pressure from 17 to 43 h, and 0.019 mM/h at high pressure, from 16 to 44 h. In control experiments without bacteria at 15 MPa the n-hexadecane also slowly decreased although with a much slower rate of 0.007 mM/h.

Bottom Line: However, above this pressure growth decreased and at 12 MPa or more no more growth was observed.Nevertheless, S. yanoikuyae continued to convert naphthalene at pressure >12 MPa, although at a lower rate than at 0.1 MPa.These results show that high pressure has a strong influence on the biodegradation of crude oil components and that, contrary to previous assumptions, the role of pressure cannot be discounted when estimating the biodegradation and ultimate fate of deep-sea oil releases such as the Deepwater Horizon event.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Technical Biocatalysis, Hamburg University of Technology, Hamburg 21073, Germany.

ABSTRACT
The blowout of the Deepwater Horizon in the Gulf of Mexico in 2010 occurred at a depth of 1500 m, corresponding to a hydrostatic pressure of 15 MPa. Up to now, knowledge about the impact of high pressure on oil-degrading bacteria has been scarce. To investigate how the biodegradation of crude oil and its components is influenced by high pressures, like those in deep-sea environments, hydrocarbon degradation and growth of two model strains were studied in high-pressure reactors. The alkane-degrading strain Rhodococcus qingshengii TUHH-12 grew well on n-hexadecane at 15 MPa at a rate of 0.16 h(-1), although slightly slower than at ambient pressure (0.36 h(-1)). In contrast, the growth of the aromatic hydrocarbon degrading strain Sphingobium yanoikuyae B1 was highly affected by elevated pressures. Pressures of up to 8.8 MPa had little effect on growth of this strain. However, above this pressure growth decreased and at 12 MPa or more no more growth was observed. Nevertheless, S. yanoikuyae continued to convert naphthalene at pressure >12 MPa, although at a lower rate than at 0.1 MPa. This suggests that certain metabolic functions of this bacterium were inhibited by pressure to a greater extent than the enzymes responsible for naphthalene degradation. These results show that high pressure has a strong influence on the biodegradation of crude oil components and that, contrary to previous assumptions, the role of pressure cannot be discounted when estimating the biodegradation and ultimate fate of deep-sea oil releases such as the Deepwater Horizon event.

No MeSH data available.


Related in: MedlinePlus