Bifidobacterium pseudolongum are efficient indicators of animal fecal contamination in raw milk cheese industry
Bifidobacterium pseudolongum are efficient indicators of animal fecal contamination in raw milk cheese industry
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DOI：
10.1186/1471-2180-11-178
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发表时间：
2011-08-04
期刊：
影响因子：
4.2
通讯作者：
Daube, Georges
中科院分区：
文献类型：
--
作者：
Delcenserie, Veronique;Gavini, Francoise;Daube, Georges
背景：使用双歧杆菌作为粪便污染指标，对来自法国两家工厂的生乳奶酪（圣马塞林奶酪和布里干酪）在多个生产步骤（生乳、添加凝乳酶后 - 圣马塞林干酪 - 或第二次熟成后 - 布里干酪 -、脱模后和熟成过程中）的污染情况进行了研究。结果：使用 PCR-RFLP 和实时 PCR 比较了双歧杆菌半定量计数。 77%（PCR-RFLP；1.75 至 2.29 log cfu ml(-1)）和 68%（实时 PCR；2.19 至 2.73 log cfu ml(-1)）的 St-Marcellin 样品以及 87%（PCR-RFLP；1.17 至 2.40 log cfu ml(-1)）的布里干酪样品中检测到假长芽孢杆菌。假长双歧杆菌的平均计数在这两个过程中保持稳定。在 St-Marcellin 的成熟阶段，还检测到了另外两个双歧杆菌种群，分别在 61% 和 18% 的样品中检测到 (PCR-RFLP)。这些种群的存在解释了在成熟过程中观察到的双歧杆菌总数的增加。目前正在对这些人群进行进一步的鉴定。 48%（St-Marcellin）和 70%（Brie）的样品呈假长双歧杆菌阳性/大肠杆菌阳性。大肠杆菌阴性，而只有 10% (St-Marcellin) 和 3% (Brie) 呈假长芽孢杆菌阴性/大肠杆菌。结论：Marcellin 工艺成熟过程中双歧杆菌总数的增加不允许将其用作粪便指示剂。整个过程中存在的假长双歧杆菌定义了来自动物源的污染，因为该物种在牛粪中占主导地位，并且从未在人类粪便中分离出来。在两种不同的奶酪加工过程中，假长芽孢杆菌作为指示剂比大肠杆菌更敏感。应使用假长芽孢杆菌而不是大肠杆菌作为粪便指示剂来评估原料奶和原料奶奶酪的质量。
Background: The contamination of raw milk cheeses (St-Marcellin and Brie) from two plants in France was studied at several steps of production (raw milk, after addition of rennet - St-Marcellin - or after second maturation - Brie -, after removal from the mold and during ripening) using bifidobacteria as indicators of fecal contamination.Results: Bifidobacterium semi-quantitative counts were compared using PCR-RFLP and real-time PCR. B. pseudolongum were detected in 77% (PCR-RFLP; 1.75 to 2.29 log cfu ml(-1)) and 68% (real-time PCR; 2.19 to 2.73 log cfu ml(-1)) of St-Marcellin samples and in 87% (PCR-RFLP; 1.17 to 2.40 log cfu ml(-1)) of Brie cheeses samples. Mean counts of B. pseudolongum remained stable along both processes. Two other populations of bifidobacteria were detected during the ripening stage of St-Marcellin, respectively in 61% and 18% of the samples (PCR-RFLP). The presence of these populations explains the increase in total bifidobacteria observed during ripening. Further characterization of these populations is currently under process. Forty-eight percents (St-Marcellin) and 70% (Brie) of the samples were B. pseudolongum positive/E. coli negative while only 10% (St-Marcellin) and 3% (Brie) were B. pseudolongum negative/E. coli positive.Conclusions: The increase of total bifidobacteria during ripening in Marcellin's process does not allow their use as fecal indicator. The presence of B. pseudolongum along the processes defined a contamination from animal origin since this species is predominant in cow dung and has never been isolated in human feces. B. pseudolongum was more sensitive as an indicator than E. coli along the two different cheese processes. B. pseudolongum should be used as fecal indicator rather than E. coli to assess the quality of raw milk and raw milk cheeses.