Jendrossek Dieter, Selchow Olaf, Hoppert Michael
Institut für Mikrobiologie, Universität Stuttgart, Allmandring 31, 70550 Stuttgart, Germany.
Appl Environ Microbiol. 2007 Jan;73(2):586-93. doi: 10.1128/AEM.01839-06. Epub 2006 Nov 3.
Localization of newly synthesized poly(3hydroxybutyrate) (PHB) granules was determined by confocal laser scanning fluorescence microscopy of Nile red-stained cells and by transmission electron microscopy (TEM). PHB granules of Nile red-stained living cells of Caryophanon latum at the early stages of PHB accumulation were frequently found at or close to the cytoplasmic membrane. TEM analysis of the same culture revealed electron-translucent globular structures resembling PHB granules that were nonrandomly distributed in the cell lumen but were frequently found at or close to the cytoplasmic membrane. Immunogold labeling using PHB-specific antiserum confirmed that the electron-translucent structures represented PHB granules. Electron microscopy examination of PHB granules after cell lysis revealed that PHB granules were often associated with membrane vesicles. Nonrandom localization of PHB granules was also found in Beijerinckia indica. Cells of this species harbored one PHB granule at each cell pole. Our results show that newly synthesized PHB granules often are close to or even in physical contact with the cytoplasmic membrane. Possible explanations for this unexpected finding and a hypothetical model of PHB granule formation in C. latum are discussed.
通过对尼罗红染色细胞进行共聚焦激光扫描荧光显微镜观察以及透射电子显微镜（TEM）分析，确定了新合成的聚（3-羟基丁酸酯）（PHB）颗粒的定位。在PHB积累早期，尼罗红染色的嗜热栖热放线菌活细胞的PHB颗粒经常出现在细胞质膜处或靠近细胞质膜的位置。对同一培养物的TEM分析显示，类似PHB颗粒的电子透明球状结构在细胞腔内呈非随机分布，但经常出现在细胞质膜处或靠近细胞质膜的位置。使用PHB特异性抗血清进行免疫金标记证实，这些电子透明结构代表PHB颗粒。细胞裂解后对PHB颗粒进行电子显微镜检查发现，PHB颗粒常与膜泡相关。在印度拜叶林克氏菌中也发现了PHB颗粒的非随机定位。该物种的细胞在每个细胞极含有一个PHB颗粒。我们的结果表明，新合成的PHB颗粒通常靠近细胞质膜，甚至与细胞质膜有物理接触。讨论了这一意外发现的可能解释以及嗜热栖热放线菌中PHB颗粒形成的假设模型。
