title: An impaired metabolic response to hydrostatic pressure explains Alcanivorax borkumensis recorded distribution in the deep marine water column.
abstract: Alcanivorax borkumensis is an ubiquitous model organism for hydrocarbonoclastic bacteria, which dominates polluted surface waters. Its negligible presence in oil-contaminated deep waters (as observed during the Deepwater Horizon accident) raises the hypothesis that it may lack adaptive mechanisms to hydrostatic pressure (HP). The type strain SK2 was tested under 0.1, 5 and 10 MPa (corresponding to surface water, 500 and 1000 m depth, respectively). While 5 MPa essentially inactivated SK2, further increase to 10 MPa triggered some resistance mechanism, as indicated by higher total and intact cell numbers. Under 10 MPa, SK2 upregulated the synthetic pathway of the osmolyte ectoine, whose concentration increased from 0.45 to 4.71 fmoles cell(-1). Central biosynthetic pathways such as cell replication, glyoxylate and Krebs cycles, amino acids metabolism and fatty acids biosynthesis, but not β-oxidation, were upregulated or unaffected at 10 MPa, although total cell number was remarkably lower with respect to 0.1 MPa. Concomitantly, expression of more than 50% of SK2 genes was downregulated, including genes related to ATP generation, respiration and protein translation. Thus, A. borkumensis lacks proper adaptation to HP but activates resistance mechanisms. These consist in poorly efficient biosynthetic rather than energy-yielding degradation-related pathways, and suggest that HP does represent a major driver for its distribution at deep-sea.
authors: Center of Microbial Ecology and Technology (CMET), University of Gent, Coupure Links 653, B 9000 Gent, Belgium.
authors: Alberto
authors: A
authors: Scoma
authors: Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milano, Via Celoria 2, 20133, Milano, Italy.
authors: Marta
authors: M
authors: Barbato
authors: Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milano, Via Celoria 2, 20133, Milano, Italy.
authors: Sara
authors: S
authors: Borin
authors: Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milano, Via Celoria 2, 20133, Milano, Italy.|Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), 4700, Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors: Daniele
authors: D
authors: Daffonchio
authors: Center of Microbial Ecology and Technology (CMET), University of Gent, Coupure Links 653, B 9000 Gent, Belgium.
authors: Nico
authors: N
authors: Boon
mesh_terms: D053521:Alcanivoraceae / Q000254:growth & development* / Q000378:metabolism; D000599:Amino Acids, Diamino / Q000096:biosynthesis; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D053898:Biosynthetic Pathways; D004261:DNA Replication; D020869:Gene Expression Profiling / Q000379:methods*; D015964:Gene Expression Regulation, Bacterial; D006874:Hydrostatic Pressure; D012623:Seawater / Q000382:microbiology; D014871:Water Microbiology
chemical_list: D000599:Amino Acids, Diamino; D001426:Bacterial Proteins; C045628:ectoine