Broda D M, De Lacy K M, Bell R G
Microbiology and Food Safety Section, Meat Industry Research Institute of New Zealand, Hamilton, New Zealand.
Int J Food Microbiol. 1998 Jan 6;39(1-2):69-78. doi: 10.1016/s0168-1605(97)00120-7.
This study was undertaken to determine the influence of culture media on the quantitative recovery of vegetative cells and spores of psychrotrophic Clostridium spp. associated with the spoilage of chilled meats. For recovery of vegetative cells and spores (presumptive counts), 24 h or 48 h broth cultures in Peptone Yeast Extract Glucose Starch (PYGS) broth were used; for spore counts, concentrated spore suspensions derived from 35-day cultures were used. For presumptive counts, seven non-selective and eight selective media were tested. Recovery of psychrotrophic clostridia with optimum growth temperatures between 15 degrees C and 20 degrees C was best with non-selective media, such as Peptone Yeast Extract Glucose Starch (PYGS) agar with lysozyme; recovery of clostridia with growth optima between 25 degrees C and 30 degrees C was best with selective media, such as Shahidi Ferguson Perfringens (SFP) agar. For organisms with the lower optimum growth temperature (heat-sensitive group) spore recovery after heat treatment (80 degrees C for 10 min) was best if a 2 M (pH 10) thioglycollate treatment (10 min at 45 degrees C) was used, followed by plating onto a lysozyme- or egg-yolk-containing medium. For organisms with the higher optimum growth temperature (heat-resistant group), spore recovery was best on Glucose Starch agar without added lysozyme. The diversity among psychrotrophic Clostridium spp. associated with chilled meat spoilage precludes the identification of a single 'best' recovery medium or technique. Consequently, a variety of complementary selective techniques and media must be used if comprehensive recovery is to be assured.
本研究旨在确定培养基对与冷藏肉变质相关的嗜冷梭菌属营养细胞和孢子定量回收的影响。为回收营养细胞和孢子（推测计数），使用了在蛋白胨酵母提取物葡萄糖淀粉（PYGS）肉汤中进行24小时或48小时的肉汤培养；为进行孢子计数，使用了源自35天培养物的浓缩孢子悬液。对于推测计数，测试了七种非选择性培养基和八种选择性培养基。对于最佳生长温度在15℃至20℃之间的嗜冷梭菌，使用非选择性培养基（如含溶菌酶的蛋白胨酵母提取物葡萄糖淀粉（PYGS）琼脂）回收效果最佳；对于最佳生长温度在25℃至30℃之间的梭菌，使用选择性培养基（如沙希迪弗格森产气荚膜梭菌（SFP）琼脂）回收效果最佳。对于最佳生长温度较低的微生物（热敏组），如果使用2M（pH 10）巯基乙酸盐处理（在45℃下处理10分钟），然后接种到含溶菌酶或蛋黄的培养基上，热处理（80℃处理10分钟）后的孢子回收效果最佳。对于最佳生长温度较高的微生物（耐热组），在不添加溶菌酶的葡萄糖淀粉琼脂上孢子回收效果最佳。与冷藏肉变质相关的嗜冷梭菌属之间的多样性使得无法确定单一的“最佳”回收培养基或技术。因此，如果要确保全面回收，必须使用多种互补的选择性技术和培养基。
