通过培养可以捕获地下微生物组的全部多样性的程度可能受到采样过程中由于减压而不可避免地丧失细胞活力的阻碍。富集,和隔离。此外,跨越地表和地下生态系统的先前分离的菌株的耐压性可以揭示这些过渡带中的微生物活动和压力适应。然而,高压富集技术可能会对高压对压电耐受和压电敏感物种的生理影响进行评估。这里,我们比较了两种高压培养技术-一种需要在采样过程中对整个培养物进行减压,另一种使用先前描述的等量异位PUSH设备-以探索在孵育过程中重复减压的影响,以表征来自深层环境的分离物。使用两个模型硫酸盐还原原核生物来测试减压/再加压循环对生长速率的影响,细胞产量,和耐压。嗜温细菌脱硫弧菌的培养温度为0.1至50MPa,并在0.1至98MPa的温度下测试了超热古细菌古细菌。对于这两种种植方法,D.salexigens显示指数增长高达20兆帕,但是等压栽培观察到更快的生长速率。此外,在30MPa时,仅在等量异位条件下,在D.salexigens培养物中观察到少量生长。等压力条件也将牛耳的指数增长延长到60兆帕,与在二次采样过程中减压培养时的50MPa相比。对于这两种菌株,生长速率和细胞产量随着压力的增加而下降,在压力范围的较高端观察到最明显的减压效果。这些结果突出表明,重复减压会对细胞活力产生显著的负面影响,这表明减压耐受性可能取决于栖息地的深度。此外,采样,富集,在等压装置中的培养不仅对于探索对减压敏感的深层生物圈部分至关重要,而且还可以更好地表征跨越地表和地下生态系统的压电耐受和压电敏感物种的压力极限和生长特征。
The extent to which the full diversity of the subsurface microbiome can be captured via cultivation is likely hindered by the inevitable loss of cellular viability from decompression during sampling, enrichment, and isolation. Furthermore, the pressure tolerance of previously isolated strains that span surface and subsurface ecosystems can shed light into microbial activity and pressure adaptation in these transition zones. However, assessments of the effects of elevated pressure on the physiology of piezotolerant and piezosensitive species may be biased by high-pressure enrichment techniques. Here, we compared two high-pressure cultivation techniques-one that requires decompression of the whole cultures during sampling and one that employs the previously described isobaric PUSH devices-to explore the effects of repeated decompression during incubations performed to characterize isolates from deep environments. Two model sulfate-reducing prokaryotes were used to test the effects of decompression/repressurization cycles on growth rates, cell yields, and pressure tolerance. The mesophilic bacterium Desulfovibrio salexigens was cultivated from 0.1 to 50 MPa, and the hyperthermophilic archaeon Archaeoglobus fulgidus was tested from 0.1 to 98 MPa. For both cultivation methods, D. salexigens showed exponential growth up to 20 MPa, but faster growth rates were observed for isobaric cultivation. Furthermore, at 30 MPa minor growth was observed in D. salexigens cultures only for isobaric conditions. Isobaric conditions also extended exponential growth of A. fulgidus to 60 MPa, compared to 50 MPa when cultures were decompressed during subsampling. For both strains, growth rates and cell yields decreased with increasing pressures, and the most pronounced effects of decompression were observed at the higher end of the pressure ranges. These results highlight that repeated decompression can have a significant negative impact on cell viability, suggesting that decompression tolerance may depend on habitat depth. Furthermore, sampling, enrichment, and cultivation in isobaric devices is critical not only to explore the portion of the deep biosphere that is sensitive to decompression, but also to better characterize the pressure limits and growth characteristics of piezotolerant and piezosensitive species that span surface and subsurface ecosystems.