Guerra Matías, González Karina, González Carlos, Parra Boris, Martínez Miguel
Department of Microbiology, Faculty of Biological Sciences, University of Concepción, Concepción, Chile.
Int Microbiol. 2015 Sep;18(3):189-94. doi: 10.2436/20.1501.01.249.
Dormancy is characterized by low metabolism and absence of protein synthesis and cellular division enabling bacterial cells to survive under stress. The aim was to determine if carbon starvation and low temperature are factors that modify the proportion of dormant/active cells in Deinococcus sp. UDEC-P1. By flow cytometry, RedoxSensor Green (RSG) was used to quantify metabolic activity and Propidium Iodide (PI) to evaluate membrane integrity in order to determine the percentage of dormant cells. Cell size and morphology were determined using scanning electronic microscopy. Under carbon starvation at 30°C, Deinococcus sp. UDEC-P1 increased its proportion of dormant cells from 0.1% to 20%, decreased the count of culturable cells and average cell volume decreased 7.1 times. At 4°C, however, the proportion of dormant cells increased only to 6%, without a change in the count of culturable cells and an average cellular volume decrease of 4.1 times and 3% of the dormant cells were able to be awakened. Results indicate a greater proportion of dormant Deinococcus sp. UDEC-P1 cells at 30ºC and it suggests that carbon starvation is more deleterious condition at 30ºC than 4ºC. For this reason Deinococcus sp. UDEC-P1 cells are more likely to enter into dormancy at higher temperature as a strategy to survive.
休眠的特征是新陈代谢缓慢、缺乏蛋白质合成和细胞分裂，这使细菌细胞能够在压力下存活。本研究的目的是确定碳饥饿和低温是否会改变嗜热放线菌属UDEC-P1中休眠/活跃细胞的比例。通过流式细胞术，使用氧化还原传感器绿（RSG）来量化代谢活性，使用碘化丙啶（PI）来评估膜完整性，以确定休眠细胞的百分比。使用扫描电子显微镜确定细胞大小和形态。在30°C的碳饥饿条件下，嗜热放线菌属UDEC-P1的休眠细胞比例从0.1%增加到20%，可培养细胞数量减少，平均细胞体积减小7.1倍。然而，在4°C时，休眠细胞的比例仅增加到6%，可培养细胞数量没有变化，平均细胞体积减小4.1倍，3%的休眠细胞能够被唤醒。结果表明，在30°C时嗜热放线菌属UDEC-P1的休眠细胞比例更高，这表明碳饥饿在30°C时比在4°C时更具有害性。因此，嗜热放线菌属UDEC-P1细胞更有可能在较高温度下进入休眠状态，作为一种生存策略。
