Abstract This study reports the prevalence of sporeforming bacteria and contamination levels of a variety of powdered dairy products from cows’, ewes’, goats’ and mares’ milk produced in France. The concentration of mesophilic spores, thermophilic spores and highly heat-resistant thermophilic spores was assessed in 61 dairy powders. Thermophilic spore concentration was highly variable between powders, likely due to the different manufacturing processes used for transforming milk into dairy powders. The different stages of processing, particularly heat treatment close to 55 °C had a strong impact on selection of thermophilic bacteria contaminating dairy powders. For some products, thermophilic spore counts were as high as 5.89 log TSC g-1. Of the 313 thermophilic isolates selected, 93.3% belonged to the species Geobacillus stearothermophilus (43.5%), Bacillus licheniformis (30.0%) and Anoxybacillus flavithermus (19.8%). These results confirm the presence of the three majority species reported worldwide.

中文翻译：

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法国乳粉中嗜热孢子形成菌的存在和多样性

摘要 本研究报告了产于法国的奶牛、母羊、山羊和马奶的各种乳粉中产芽孢细菌的流行情况和污染水平。对 61 种乳粉中嗜温孢子、嗜热孢子和高耐热嗜热孢子的浓度进行了评估。不同粉末之间的嗜热孢子浓度差异很大，这可能是由于将牛奶转化为乳粉所使用的制造工艺不同。加工的不同阶段，特别是接近 55°C 的热处理对污染乳粉的嗜热细菌的选择有很大影响。对于某些产品，嗜热孢子数高达 5.89 log TSC g-1。在选择的 313 个嗜热分离株中，93.3% 属于嗜热脂肪地芽孢杆菌 (43. 5%)、地衣芽孢杆菌 (Bacillus licheniformis) (30.0%) 和 Anoxybacillus flavithermus (19.8%)。这些结果证实了世界范围内报道的三种主要物种的存在。