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

Abstract

The Hatton–Rockall Basin (North‐East Atlantic) is an area with potential for deep‐sea (2,900 m) hydrocarbon exploration. Following the Deepwater Horizon oil spill, many investigations into the responses of sediment microbial communities to oil pollution have been undertaken. However, hydrostatic pressure is a parameter that is often omitted due to the technical difficulties associated with conducting experiments at high pressure (>10 MPa). In this study, sediments from 2,900 m in the Hatton–Rockall Basin, following a one‐week decompression period in a temperature‐controlled room at 5°C, were incubated in factorial combinations of 0.1 and 30 MPa, 5 and 20°C, and contamination with a hydrocarbon mixture or uncontaminated controls to evaluate the effect of these environmental variables on the bacterial community composition. Our results revealed varying effects of pressure, temperature, and oil contamination on the composition of the bacterial community within the sediment. Temperature was the strongest determinant of differences in the bacterial community structure between samples followed by pressure. Oil contamination did not exert a strong change in the sediment bacterial community structure when pressure and temperature conditions were held at in situ levels (30 MPa and 5°C). The γ‐proteobacteria Pseudomonas and Colwellia, and several Bacteroidetes dominated communities at 30 MPa. In contrast, hydrocarbon degraders such as Halomonas , Alcanivorax, and Marinobacter decreased in relative abundance at the same pressure. This study highlights the importance of considering hydrostatic pressure in ex situ investigations into hydrocarbon‐degrading deepwater microbial communities.

Chemical Profiling Provides Insights into the Metabolic Machinery of Hydrocarbon-Degrading Deep-Sea Microbes

“…These findings suggest that the in vitro conditions established in this study did not support growth of all microbes; however, as expected the microbes that did survive were associated with hydrocarbon-degrading properties ( 32 ). Similar observations were made in a previous study simulating deep-sea environments (pressure, 0.1 and 30 MPa; temperature, 5 and 20°C) where the microbial community structure remained similar at the phylum level but differed at the taxon level ( 39 ).…”

Inoculum origin, incubation temperature and mild hydrostatic pressure modulate growth and activity of anaerobic saline communities

“…In consequence, the absolute abundance of non-adapted groups is reduced, allowing the establishment of predominant groups whose physiological features allow them to survive under stress conditions (75). In the case of the concomitant action of mHP and temperature, it has been pointed out a more significant effect of temperature as a diversity modifier (23). In our experiments, the exposure to higher mHP decreased absolute abundance (Figure 9 83) is worth mentioning.…”

“…Incubation under increasing HHP decreased the absolute abundance of archaea and generated a community predominantly dominated by bacteria (90%) mostly associated with the phylum Gammaproteobacteria (22). Other phyla such as Proteobacteria, Bacteroidetes, Actinobacteria, Flavobacteria and Firmicutes (2) had become predominant when samples from diverse habitats, namely coastal sediments and surface marine water were incubated at HHP (23). In the subsurface, the exposure to high-salinity, temperature and HHP conditions reduced the richness and diversity of microbial communities, including members of the above-mentioned phyla (24).…”

A Review and Bibliometric Analysis on Applications of Microbial Degradation of Hydrocarbon Contaminants in Arctic Marine Environment at Metagenomic and Enzymatic Levels

“…Cold-acclimated microorganisms such as PAHs-degrading Pseudomonads ( β -Proteobacteria) and Sphingobium sp. C100 ( α -Proteobacteria) were enriched in the deep-sea sediments of the Arctic Ocean [ 99 ], Marinomonas profundimaris D104 [ 100 ], while Colwellia was present in the Svalbard sea ice of the Arctic [ 101 , 102 ]. The majority of hydrocarbons (94%) were degraded by the bacterial communities present in sub-ice seawater of the Arctic by removing almost all the biodegradable alkanes and similarly for the methylated forms of PAHs.…”