Lezcano María Ángeles, Carrizo Daniel, Lominchar Miguel Ángel, Sánchez-García Laura, Quesada Antonio, Parro Víctor
Centro de Astrobiología (CAB), CSIC-INTA, 28850, Torrejón de Ardoz, Madrid, Spain.
IMDEA Water Institute, Avenida Punto Com 2, 28805, Alcalá de Henares, Madrid, Spain.
Microb Ecol. 2025 Jul 31;88(1):84. doi: 10.1007/s00248-025-02583-4.
Ancient Antarctic microbial mats harbour viable bacteria that have been exposed to extreme cold and arid conditions for hundreds of years. To delve into the molecular mechanisms underlaying their survival, we isolated 12 bacterial strains from a 1,000-year-old desiccated microbial mat from the McMurdo Ice Shelf and studied their lipid composition as a function of temperature. Six of the bacterial strains were classified as Paenisporosarcina macmurdoensis, and the other six as Arthrobacter sp., according to 16S rRNA gene analyses. Two strains of each taxon were incubated at their minimum and maximum growth temperatures, and the changes in their lipid profiles were analyzed. The proportion of major fatty acids (saturated, unsaturated, and iso- and anteiso-) remained relatively constant across temperature in the four strains, but the composition of hydrocarbons and alcohols differed between taxa (e.g., presence of unsaturated alkenes in Arthrobacter sp., or unidentified isoprenoid alcohols in P. macmurdoensis). This highlights the diagnostic value of non-fatty acid lipids and revealed a taxon-dependent lipid composition. Despite the taxon-associated lipid profile, incubation temperature also influenced lipid composition in both taxa, with higher temperature correlating with greater lipid richness. Interestingly, the two P. macmurdoensis strains showed distinct lipid profiles at 20°C, suggesting that intraspecific lipid diversity reflects within-species physiological variability with potential relevance for adaptation to temperature fluctuations in the mat. Therefore, assessing the influence of temperature on bacterial lipids is crucial for understanding their adaptation and survival in extreme environments, as well as for expanding species lipid inventories for biological interpretations of ancient samples.
古老的南极微生物垫中含有存活了数百年的细菌，这些细菌一直处于极端寒冷和干旱的环境中。为了深入研究它们生存的分子机制，我们从麦克默多冰架上一块有1000年历史的干燥微生物垫中分离出12株细菌菌株，并研究了它们的脂质组成随温度的变化。根据16S rRNA基因分析，其中6株细菌菌株被归类为麦克默多拟芽孢八叠球菌，另外6株为节杆菌属。将每个分类单元的两株菌株分别在其最低和最高生长温度下培养，并分析它们脂质谱的变化。在这四株菌株中，主要脂肪酸（饱和脂肪酸、不饱和脂肪酸、异分支脂肪酸和anteiso-脂肪酸）的比例在不同温度下相对保持恒定，但不同分类单元的碳氢化合物和醇类组成有所不同（例如，节杆菌属中存在不饱和烯烃，或麦克默多拟芽孢八叠球菌中存在未鉴定的类异戊二烯醇）。这突出了非脂肪酸脂质的诊断价值，并揭示了分类单元依赖性脂质组成。尽管存在与分类单元相关的脂质谱，但培养温度也影响了两个分类单元的脂质组成，温度越高，脂质丰富度越高。有趣的是，两株麦克默多拟芽孢八叠球菌菌株在20°C时显示出不同的脂质谱，这表明种内脂质多样性反映了物种内部的生理变异性，这可能与适应微生物垫中的温度波动有关。因此，评估温度对细菌脂质的影响对于理解它们在极端环境中的适应和生存至关重要，同时对于扩展物种脂质清单以用于对古代样本进行生物学解释也至关重要。
