Ghosh Sonali, Korza George, Maciejewski Mark, Setlow Peter
Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, Connecticut, USA.
Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, Connecticut, USA
J Bacteriol. 2015 Mar;197(5):992-1001. doi: 10.1128/JB.02520-14. Epub 2014 Dec 29.
This work was undertaken to obtain information on levels of metabolism in dormant spores of Bacillus species incubated for weeks at physiological temperatures. Spores of Bacillus megaterium and Bacillus subtilis strains were harvested shortly after release from sporangia and incubated under various conditions, and dormant spore metabolism was monitored by (31)P nuclear magnetic resonance (NMR) analysis of molecules including 3-phosphoglyceric acid (3PGA) and ribonucleotides. Incubation for up to 30 days at 4, 37, or 50°C in water, at 37 or 50°C in buffer to raise the spore core pH from ∼6.3 to 7.8, or at 4°C in spent sporulation medium caused no significant changes in ribonucleotide or 3PGA levels. Stage I germinated spores of Bacillus megaterium that had slightly increased core water content and a core pH of 7.8 also did not degrade 3PGA and accumulated no ribonucleotides, including ATP, during incubation for 8 days at 37°C in buffered saline. In contrast, spores incubated for up to 30 days at 37 or 50°C in spent sporulation medium degraded significant amounts of 3PGA and accumulated ribonucleotides, indicative of RNA degradation, and these processes were increased in B. megaterium spores with a core pH of ∼7.8. However, no ATP was accumulated in these spores. These data indicate that spores of Bacillus species stored in water or buffer at low or high temperatures exhibited minimal, if any, metabolism of endogenous compounds, even when the spore core pH was 7.8 and core water content was increased somewhat. However, there was some metabolism in spores stored in spent sporulation medium.
开展这项工作是为了获取有关芽孢杆菌属休眠孢子在生理温度下培养数周后的代谢水平信息。巨大芽孢杆菌和枯草芽孢杆菌菌株的孢子在从孢子囊中释放后不久收获，并在各种条件下培养，通过对包括3-磷酸甘油酸（3PGA）和核糖核苷酸在内的分子进行（31）P核磁共振（NMR）分析来监测休眠孢子的代谢。在4、37或50°C的水中培养30天，在37或50°C的缓冲液中培养以将孢子核心pH从约6.3提高到7.8，或在4°C的陈旧芽孢形成培养基中培养，核糖核苷酸或3PGA水平均无显著变化。巨大芽孢杆菌处于第一阶段的萌发孢子，其核心含水量略有增加，核心pH为7.8，在37°C的缓冲盐水中培养8天期间，也不会降解3PGA，也不会积累包括ATP在内的核糖核苷酸。相比之下，在陈旧芽孢形成培养基中于37或50°C培养长达30天的孢子会降解大量3PGA并积累核糖核苷酸，这表明存在RNA降解，并且在核心pH约为7.8的巨大芽孢杆菌孢子中这些过程有所增加。然而，这些孢子中没有积累ATP。这些数据表明，即使孢子核心pH为7.8且核心含水量有所增加，在低温或高温下保存在水或缓冲液中的芽孢杆菌属孢子对内源化合物的代谢也极少（如果有代谢的话）。然而，保存在陈旧芽孢形成培养基中的孢子会有一些代谢。
