College of Food Science and Technology, Hebei Normal University of Science and Technology, Qinhuangdao, 066004 China.
College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083 China.
Indian J Microbiol. 2013 Sep;53(3):352-8. doi: 10.1007/s12088-013-0373-4. Epub 2013 Mar 6.
To clarify the mechanism of microbial inactivation by supercritical carbon dioxide (SCCO2), membrane damage of Rhodotorula mucilaginosa was investigated within specific pressure (10 Mpa), temperature (37 °C), and treatment time (10-70 min) ranges, including cell morphological structure, membrane permeability and fluidity. SEM and TEM observations showed morphological changes in the cell envelope and intracellular organization after SCCO2 treatment. Increase of membrane permeability was measured as increased uptake of the trypan blue dye with microscopy, and leakage of intracellular substances such as UV-absorbing materials and ions by determining the change of protein and electrical conductivity. The SCCO2 mediated reduction in CFU ml(-1) was 0.5-1 log higher at 37 °C and 10 MPa for 60 min in Rose Bengal Medium containing 4 % sodium than a similar treatment in Rose Bengal Medium. Membrane fluidity analyzed by fluorescence polarization method using 1,6-diphenyl-1,3,5-hexatriene showed that the florescence polarization and florescence anisotropy of the SCCO2-treated cells were increased slightly and gently compared with the untreated cells. The correlation between membrane damage and death of cells under SCCO2 was clear, and the membrane damage was a key factor induced the inactivation of cells.
为了阐明超临界二氧化碳（SCCO2）对微生物失活的作用机制，在特定压力（10 MPa）、温度（37°C）和处理时间（10-70 min）范围内，研究了粘红酵母的膜损伤，包括细胞形态结构、膜通透性和流动性。SEM 和 TEM 观察显示，SCCO2 处理后细胞包膜和细胞内组织发生形态变化。用显微镜测量透膜性增加，通过测定蛋白质和电导率的变化来检测细胞内物质（如紫外吸收物质和离子）的泄漏，发现摄取锥虫蓝染料增加。在含有 4% 氯化钠的孟加拉玫瑰红培养基中，37°C 和 10 MPa 下处理 60 min，SCCO2 介导的 CFU ml(-1) 减少比在孟加拉玫瑰红培养基中类似处理高 0.5-1 对数。用 1,6-二苯基-1,3,5-己三烯通过荧光偏振法分析膜流动性，与未经处理的细胞相比，SCCO2 处理的细胞的荧光偏振和荧光各向异性略有增加且较为温和。SCCO2 下细胞死亡与膜损伤之间的相关性很明显，膜损伤是导致细胞失活的关键因素。
