Kaletunç Gönül, Lee Jaesung, Alpas Hami, Bozoglu Faruk
Department of Food, Agricultural and Biological Engineering, Ohio State University, Columbus, Ohio 43210, USA.
Appl Environ Microbiol. 2004 Feb;70(2):1116-22. doi: 10.1128/AEM.70.2.1116-1122.2004.
Scanning electron microcopy (SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) were used to evaluate structural changes in Leuconostoc mesenteroides cells as a function of high-hydrostatic-pressure treatment. This bacterium usually grows in chains of cells, which were increasingly dechained at elevated pressures. High-pressure treatments at 250 and 500 MPa also caused changes in the external surface and internal structure of cells. Dechaining and blister formation on the surface of cells increased with pressure, as observed in SEM micrographs. TEM studies showed that cytoplasmic components of the cells were affected by high-pressure treatment. DSC studies of whole cells showed increasing denaturation of ribosomes with pressure, in keeping with dense compacted regions in the cytoplasm of pressure-treated cells observed in TEM micrographs. Apparent reduction of intact ribosomes observed in DSC thermograms was related to the reduction in number of viable cells. The results indicate that inactivation of L. mesenteroides cells is mainly due to ribosomal denaturation observed as a reduction of the corresponding peak in DSC thermograms and condensed interior regions of cytoplasm in TEM micrographs.
采用扫描电子显微镜（SEM）、透射电子显微镜（TEM）和差示扫描量热法（DSC）来评估嗜热栖热放线菌细胞结构变化与高静水压处理之间的关系。这种细菌通常以细胞链形式生长，在压力升高时细胞链会逐渐解链。250和500兆帕的高压处理也会导致细胞外表面和内部结构发生变化。如扫描电子显微镜照片所示，细胞表面的解链和气泡形成随压力增加而增加。透射电子显微镜研究表明，细胞的细胞质成分受到高压处理的影响。对全细胞的差示扫描量热法研究表明，核糖体的变性随压力增加，这与透射电子显微镜照片中观察到的经压力处理细胞细胞质中的致密压缩区域一致。差示扫描量热图中观察到的完整核糖体明显减少与活细胞数量减少有关。结果表明，嗜热栖热放线菌细胞的失活主要是由于核糖体变性，这在差示扫描量热图中表现为相应峰的降低，在透射电子显微镜照片中表现为细胞质内部区域的浓缩。
