Center for Food Safety and Animal Health, College of Veterinary Medicine, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul, The Republic of Korea.
J Food Prot. 2012 Jul;75(7):1342-5. doi: 10.4315/0362-028X.JFP-11-519.
Mannitol-yolk-polymyxin B agar (MYPA) was modified by supplementation with trimethoprim. The ability of the supplemented medium to select for and recover Bacillus cereus from pure cultures and food samples with high background microflora was compared with MYPA. For evaluation of the modified MYPA (mMYPA) in food samples with high background microflora, B. cereus was experimentally spiked into red pepper powder, fermented soybean paste, vegetable salad, and radish sprouts, and then it was recovered on MYPA and mMYPA for comparison. In all food samples, there was no difference in recoverability (P > 0.05) between mMYPA (red pepper powder, 3.34 ± 0.24 log CFU/g; fermented soybean paste, 3.52 ± 0.47 log CFU/g; vegetable salad, 3.51 ± 0.23 log CFU/g; radish sprouts, 3.32 ± 0.40 log CFU/g) and MYPA (red pepper powder, 3.18 ± 0.20 log CFU/g; fermented soybean paste, 3.33 ± 0.43 log CFU/g; vegetable salad, 3.36 ± 0.19 log CFU/g; radish sprouts, 3.33 ± 0.31 log CFU/g). However, mMYPA exhibited better selectivity than MYPA, because additional trimethoprim made the differentiation of suspected colonies easier by inhibiting competing flora. The addition of trimethoprim to conventional media could be a useful option to improve selectivity in foods with high background microflora.
甘露醇-卵黄-多黏菌素 B 琼脂（MYPA）通过添加甲氧苄啶进行了改良。比较了添加培养基和 MYPA 从高背景微生物区系的纯培养物和食品样品中选择和回收蜡样芽孢杆菌的能力。为了评估高背景微生物区系食品中改良的 MYPA（mMYPA），将蜡样芽孢杆菌实验性地掺入辣椒粉、发酵豆酱、蔬菜沙拉和萝卜芽中，然后在 MYPA 和 mMYPA 上回收进行比较。在所有食品样品中，mMYPA（辣椒粉，3.34±0.24 log CFU/g；发酵豆酱，3.52±0.47 log CFU/g；蔬菜沙拉，3.51±0.23 log CFU/g；萝卜芽，3.32±0.40 log CFU/g）和 MYPA（辣椒粉，3.18±0.20 log CFU/g；发酵豆酱，3.33±0.43 log CFU/g；蔬菜沙拉，3.36±0.19 log CFU/g；萝卜芽，3.33±0.31 log CFU/g）的回收率没有差异（P＞0.05）。然而，mMYPA 表现出比 MYPA 更好的选择性，因为额外的甲氧苄啶通过抑制竞争菌群使可疑菌落的分化更容易。在高背景微生物区系的食品中添加甲氧苄啶可能是提高选择性的一种有用选择。
