Comparative analysis of the diversity of aerobic spore-forming bacteria in raw milk from organic and conventional dairy farms
Comparative analysis of the diversity of aerobic spore-forming bacteria in raw milk from organic and conventional dairy farms
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DOI：
10.1016/j.syapm.2008.03.002
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发表时间：
2008-06-01
影响因子：
3.4
通讯作者：
Heyndrickx, Marc
中科院分区：
文献类型：
--
作者：
Coorevits, An;De Jonghe, Valerie;Heyndrickx, Marc
原料奶的细菌污染可能来自不同的来源：空气、挤奶设备、饲料、土壤、粪便和草。据推测，奶牛饲养和圈养策略的差异可能会影响牛奶的微生物质量。通过比较有机和传统奶牛场牛奶中的需氧孢子形成植物群，研究了这一假设。实验室巴氏消毒牛奶样品从五个传统的和五个有机奶牛场，在夏末/秋季和冬季采样，被镀上一个标准的培养基和两个差分媒体，一个筛选磷脂分解和其他蛋白水解活性的细菌。获得了近930个分离物，其中898个可以通过脂肪酸甲酯分析进行筛选。采用16 S rRNA基因测序和（GTG）（5）-PCR进一步分析代表性分离株。牛奶中的大多数需氧芽孢形成菌属于芽孢杆菌属，并且与地衣芽孢杆菌、短小芽孢杆菌、环状芽孢杆菌、枯草芽孢杆菌的模式菌株和蜡状芽孢杆菌组的物种的模式菌株显示出至少97%的16 S rRNA基因序列相似性。约7%的菌株可能属于新的孢子形成类群。尽管有机奶牛场与传统奶牛场牛奶中需氧孢子形成细菌的总体多样性高度相似，但观察到两者之间存在一些差异：（i）与有机奶牛场相比，传统奶牛场牛奶中耐热微生物的数量相对较高（41.2% vs. 25.9%），以及（ii）B的数量相对较高。有机牛奶中的蜡状芽孢杆菌群微生物（81.3%）和常规牛奶中的热球脲杆菌（85.7%）。这些差异之一是B的发生率较高。来自有机奶牛场的牛奶中的蜡状菌群生物，可能与两种类型的奶牛场之间的饲养策略的差异有关。然而，没有合理的澄清，发现相对较高数量的耐热微生物和较高的发生率U。来自传统奶牛场的牛奶中存在嗜热球腔菌。这可能是由于喂养策略的差异，但没有发现支持这一假设的决定性迹象。(C)2008年Elsevier GmbH。All rights reserved.
Bacterial contamination of raw milk can originate from different sources: air, milking equipment, feed, soil, faeces and grass. It is hypothesized that differences in feeding and housing strategies of cows may influence the microbial quality of milk. This assumption was investigated through comparison of the aerobic spore-forming flora in milk from organic and conventional dairy farms. Laboratory pasteurized milk samples from five conventional and five organic dairy farms, sampled in late summer/autumn and in winter, were plated on a standard medium and two differential media, one screening for phospholipolytic and the other for proteolytic activity of bacteria. Almost 930 isolates were obtained of which 898 could be screened via fatty acid methyl ester analysis. Representative isolates were further analysed using 16S rRNA gene sequencing and (GTG)(5)-PCR. The majority of aerobic spore-formers in milk belonged to the genus Bacillus and showed at least 97% 16S rRNA gene sequence similarity with type strains of Bacillus licheniformis, Bacillus pumilus, Bacillus circulans, Bacillus subtilis and with type strains of species belonging to the Bacillus cereus group. About 7% of all isolates may belong to possibly new spore-forming taxa. Although the overall diversity of aerobic spore-forming bacteria in milk from organic vs. conventional dairy farms was highly similar, some differences between both were observed: (i) a relatively higher number of thermotolerant organisms in milk from conventional dairy farms compared to organic farms (41.2% vs. 25.9%), and (ii) a relatively higher number of B. cereus group organisms in milk from organic (81.3%) and Ureibacillus thermosphaericus in milk from conventional (85.7%) dairy farms. One of these differences, the higher occurrence of B. cereus group organisms in milk from organic dairy farms, may be linked to differences in housing strategy between the two types of dairy farming. However, no plausible clarification was found for the relatively higher number of thermotolerant organisms and the higher occurrence of U. thermosphaericus in milk from conventional dairy farms. Possibly this is due to differences in feeding strategy but no decisive indications were found to support this assumption. (C) 2008 Elsevier GmbH. All rights reserved.