Harrison Jesse P, Hallsworth John E, Cockell Charles S
UK Centre for Astrobiology, School of Physics and Astronomy, The University of Edinburgh, Edinburgh, United Kingdom
Institute for Global Food Security, School of Biological Sciences, Medical Biology Centre, Queen's University Belfast, Belfast, United Kingdom.
Appl Environ Microbiol. 2015 Mar;81(6):2156-62. doi: 10.1128/AEM.03639-14. Epub 2015 Jan 16.
The limits to biological processes on Earth are determined by physicochemical parameters, such as extremes of temperature and low water availability. Research into microbial extremophiles has enhanced our understanding of the biophysical boundaries which define the biosphere. However, there remains a paucity of information on the degree to which rates of microbial multiplication within extreme environments are determined by the availability of specific chemical elements. Here, we show that iron availability and the composition of the gaseous phase (aerobic versus microaerobic) determine the susceptibility of a marine bacterium, Halomonas hydrothermalis, to suboptimal and elevated temperature and salinity by impacting rates of cell division (but not viability). In particular, iron starvation combined with microaerobic conditions (5% [vol/vol] O2, 10% [vol/vol] CO2, reduced pH) reduced sensitivity to temperature across the 13°C range tested. These data demonstrate that nutrient limitation interacts with physicochemical parameters to determine biological permissiveness for extreme environments. The interplay between resource availability and stress tolerance, therefore, may shape the distribution and ecology of microorganisms within Earth's biosphere.
地球上生物过程的限制因素由物理化学参数决定，如极端温度和低水分可利用性。对微生物嗜极菌的研究增进了我们对界定生物圈的生物物理边界的理解。然而，关于极端环境中微生物繁殖速率在多大程度上由特定化学元素的可利用性所决定，目前仍缺乏相关信息。在此，我们表明铁的可利用性和气态相组成（需氧与微需氧）通过影响细胞分裂速率（而非活力），决定了海洋细菌嗜热栖热单胞菌对次优温度和盐度以及高温和高盐度的敏感性。特别是，缺铁与微需氧条件（5%[体积/体积]O₂、10%[体积/体积]CO₂、pH降低）相结合，降低了在所测试的13°C温度范围内对温度的敏感性。这些数据表明，营养限制与物理化学参数相互作用，以确定极端环境下的生物许可性。因此，资源可利用性与胁迫耐受性之间的相互作用可能会塑造地球生物圈中微生物的分布和生态。
