This work examines the physiologic basis of stress tolerance in bacterial strains of the genus Rhodanobacter that dominate in the acidic and highly metal contaminated near-source subsurface zone of the Oak Ridge Integrated Field Research Challenge (ORIFRC) site. Tolerance of R. denitrificans to levels of different stresses were studied in synthetic groundwater medium and R2A broth. Two strains of R. denitrificans, strains 2APBS1^T and 116–2, tolerate low to circumneutral pH (4-8), high Uranium (1 mmol/L), elevated levels of nitrate (400 mmol/L) and high NaCl (2.5%). A combination of physiologic traits, such as growth at low pH, increased growth in the presence of high organics concentration, and tolerance of high concentrations of nitrate, NaCl and heavy metals is likely responsible for dominance of Rhodanobacter at the ORIFRC site. Furthermore, extended incubation times and use of low carbon media, better approximating site groundwater conditions, are critical for accurate determination of stress responses. This study expands knowledge of the ecophysiology of bacteria from the genus Rhodanobacter and identifies methodological approaches necessary for acquiring accurate tolerance data.

这项工作研究了在橡树岭综合野外研究挑战赛（ORIFRC）地点的酸性和高度金属污染的近源地下区域中占支配地位的Rhodanobacter属菌株的耐应力性的生理基础。研究了合成地下水介质和R2A肉汤中反硝化杆菌对不同胁迫水平的耐受性。两株反硝化杆菌，菌株2APBS1 ^T和116–2，可耐受低至中性pH（4-8），高铀（1 mmol / L），硝酸盐（400 mmol / L）和高氯化钠（2.5％）。生理特征的组合，例如在低pH值下生长，在高有机物浓度下的生长增加以及对高浓度硝酸盐，NaCl和重金属的耐受性，可能是导致ORIFRC站点上罗丹杆菌占优势的原因。此外，延长孵育时间和使用低碳培养基，更好地近似现场地下水条件，对于准确确定应力响应至关重要。这项研究拓宽了红景天属细菌的生态生理知识，并确定了获取准确的耐受性数据所必需的方法学方法。