INRA, UR 545, Fromagères, 20 côte de Reyne, F-15000 Aurillac, France.
Int J Food Microbiol. 2012 May 15;156(2):91-101. doi: 10.1016/j.ijfoodmicro.2012.03.007. Epub 2012 Mar 15.
The purpose of this study was to characterize microbial biofilms from 'gerles' (wooden vats for making PDO Salers cheese) and identify their role in milk inoculation and in preventing pathogen development. Gerles from ten farms producing PDO Salers cheese were subjected to microbial analysis during at least 4 periods spread over two years. They were distinguished by their levels of Lactobacillus (between 4.50 and 6.01 log CFU/cm(2)), Gram negative bacteria (between 1.45 and 4.56 log CFU/cm(2)), yeasts (between 2.91 and 5.57 log CFU/cm(2)), and moulds (between 1.72 and 4.52 log CFU/cm(2)). They were then classed into 4 groups according their microbial characteristics. These 4 groups were characterized by different milk inoculations (with either sour whey or starter culture, daily or not), and different washing procedures (with water or whey from cheese making). The farm gerles were not contaminated by Salmonella, Listeria monocytogenes or Staphylococcus aureus. Only one slight, punctual contamination was found on one gerle among the ten studied. Even when the milk was deliberately contaminated with L. monocytogenes and S. aureus in the 40 L experimental gerles, these pathogens were found neither on the gerle surfaces nor in the cheeses. Using 40 L experimental gerles it was shown that the microbial biofilms on the gerle surfaces formed in less than one week and then remained stable. They were mainly composed of a great diversity of lactic acid bacteria (Leuconostoc pseudomesenteroides, Lactococcus lactis, Lactobacillus casei, Lactobacillus plantarum, Lactobacillus hilgardii,…), Gram positive catalase positive bacteria (Curtobacterium flaccumfaciens, Curtobacterium oceanosedimentum Citrococcus spp., Brachybacterium rhamnosum, Kocuria rhizophila, Arthrobacter spp.…) and yeast (Kluyveromyces lactis, Kluyveromyces marxianus). In less than 1 min, even in a 500 L farm gerle, the gerle's microbial biofilm can inoculate pasteurized milk with micro-organisms at levels superior to those in raw milk.
本研究的目的是对“gerles”（用于制作 PDO 萨莱奶酪的木制大桶）中的微生物生物膜进行特征描述，并确定其在牛奶接种和防止病原体发展方面的作用。在两年内的至少 4 个时期，对来自 10 个生产 PDO 萨莱奶酪的农场的 gerles 进行了微生物分析。它们的特征是乳杆菌（4.50 至 6.01 log CFU/cm(2))、革兰氏阴性菌（1.45 至 4.56 log CFU/cm(2))、酵母（2.91 至 5.57 log CFU/cm(2)) 和霉菌（1.72 至 4.52 log CFU/cm(2))。然后根据它们的微生物特性将它们分为 4 组。这 4 组的特点是不同的牛奶接种方式（使用酸乳或 starter culture，每天或不使用）和不同的洗涤程序（使用水或奶酪制作中的乳清）。在这 10 个研究的 gerles 中，没有发现沙门氏菌、单增李斯特菌或金黄色葡萄球菌污染。只有一个 gerle 出现了一次轻微的、局部的污染。即使在 40L 的实验 gerles 中故意将单核细胞增生李斯特菌和金黄色葡萄球菌污染牛奶，也未在 gerle 表面或奶酪中发现这些病原体。使用 40L 的实验 gerles 表明，gerle 表面的微生物生物膜在不到一周的时间内形成，然后保持稳定。它们主要由多种乳酸菌（肠膜明串珠菌、乳球菌乳脂亚种、干酪乳杆菌、植物乳杆菌、希氏乳杆菌等）、革兰氏阳性过氧化氢酶阳性菌（短状杆菌、海栖栖油杆菌属、柠檬酸球菌属、短双歧杆菌、罗伊氏乳杆菌属等）和酵母（乳酸克鲁维酵母、马克斯克鲁维酵母）组成。不到 1 分钟，即使在 500L 的农场 gerles 中，gerle 的微生物生物膜也可以用高于生奶水平的微生物接种巴氏杀菌奶。
