Abstract Biofilms can be formed on the surfaces of dairy processing equipment and are a potential source of product contamination. This study evaluated the diversity of multispecies biofilms formed on stainless steel (SS) due to the contaminating microbiota in raw milk. Samples of raw milk were used: one was fresh milk and the other maintained in refrigerated bulk tanks for up to 48 h. The mesophilic aerobic contamination was ∼104 CFU ml−1 in fresh milk and 106 CFU ml−1 in bulk milk. SS coupons were kept immersed in the milk at 7 ±2 °C for 10 days, and every two days, the raw milk was changed for samples of the same origin collected on the current day. After incubation for 10 days, sessile cells in the biofilm reached 105 CFU cm−2 in the presence of fresh milk, and 106 CFU cm−2 in the presence of bulk milk. The genetic diversity analysis showed that Gammaproteobacteria and Bacilli predominated in the biofilms throughout the incubation of both milk samples and these biofilms showed a reduction in diversity over time. The main classes of bacteria found in these biofilms have representatives of great importance since many of them have spoilage potential.

中文翻译：

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原奶中污染微生物群形成的多物种生物膜

摘要 生物膜可在乳制品加工设备的表面形成，是产品污染的潜在来源。本研究评估了由于生乳中的污染微生物群而在不锈钢 (SS) 上形成的多物种生物膜的多样性。使用了原料奶样品：一种是鲜奶，另一种在冷藏散装罐中保存长达 48 小时。中温需氧污染在新鲜牛奶中为 104 CFU ml-1，在散装牛奶中为 106 CFU ml-1。SS 试片在 7±2°C 的牛奶中浸泡 10 天，每两天更换一次生奶，用于当天采集的相同来源的样品。孵育 10 天后，生物膜中的固着细胞在新鲜牛奶存在下达到 105 CFU cm-2，在散装牛奶存在下达到 106 CFU cm-2。遗传多样性分析表明，在两种牛奶样品的整个孵育过程中，生物膜中的伽马变形菌和芽孢杆菌占主导地位，并且这些生物膜的多样性随着时间的推移而减少。在这些生物膜中发现的主要细菌类别具有重要意义，因为它们中的许多具有腐败潜力。