Hydrostatic pressures (HP) <30–40 MPa are often considered mild, and their impact on petroleum biodegradation seldom considered. However, the frequent use of nutrient-rich media in lab-scale high-pressure reactors may exaggerate HP importance by resulting in a strong growth stimulation as compared to oligotrophic marine environments. Here, we tested coastal seawater microbial communities, presumably enriched in pressure-sensitive microorganisms. Limiting environmental conditions for growth were applied (i.e. low temperature [5°C], no added nutrients) and HP tested at 0.1 and 15 MPa, using crude oils from three different reservoirs. The cell number was not affected by HP contrary to the microbial community composition (based on 16S rRNA gene and 16S rRNA sequences). The most predominant genera were Zhongshania, Pseudomonas and Colwellia. The enrichment of Zhongshania was crude-oil dependent and comparable at 0.1 and 15 MPa, thus showing a piezotolerant phenotype under the present conditions; Pseudomonas’ was crude-oil dependent at 0.1 MPa but unclear at 15 MPa. Colwellia was selectively enriched in the absence of crude oil and suppressed at 15 MPa. HP shaped the assemblage of oil-degrading communities even at mild levels (i.e. 15 MPa), and should thus be considered as a fundamental factor to assess oil bioremediation along the water column.

中文翻译：

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轻度的静水压力（15 MPa）影响在限制条件下（5°C，未添加营养物）测试的石油降解沿海微生物群落的组装，但不影响其生长。

静水压力（HP）<30–40 MPa通常被认为是温和的，很少考虑它们对石油生物降解的影响。但是，与贫营养的海洋环境相比，实验室规模的高压反应器中经常使用富含营养的培养基可能会导致强烈的生长刺激，从而夸大了HP的重要性。在这里，我们测试了可能富含压敏微生物的沿海海水微生物群落。应用了限制生长的环境条件（即低温[5°C]，未添加营养物），并使用来自三个不同储层的原油在0.1和15 MPa下对HP进行了测试。与微生物群落组成相反（基于16S rRNA基因和16S rRNA序列），细胞数不受HP影响。最主要的属是中山菌，假单胞菌和Colwellia。中山的富集取决于原油，并且在0.1和15 MPa时具有可比性，因此在当前条件下显示出耐压电的表型。假单胞菌在0.1 MPa时取决于原油，但在15 MPa时不清楚。Colwellia在不存在原油的情况下选择性富集，并在15 MPa时被抑制。高压即使在中等水平（即15 MPa）下也能降解石油降解群落，因此应被视为评估沿水柱进行生物修复的基本因素。