Macuamule C L S, Wiid I J, van Helden P D, Tanner M, Witthuhn R C
Department of Food Science, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch 7602, South Africa.
DST-NRF Centre of Excellence for Biomedical Tuberculosis Research, SAMRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 19063, Tygerberg 7505, South Africa.
Int J Food Microbiol. 2016 Jan 18;217:170-6. doi: 10.1016/j.ijfoodmicro.2015.10.024. Epub 2015 Oct 25.
Mycobacterium bovis that causes Bovine tuberculosis (BTB) can be transmitted to humans thought consumption of raw and raw fermented milk products from diseased animals. Lactic acid bacteria (LAB) used in popular traditional milk products in Africa produce anti-microbial compounds that inhibit some pathogenic and spoilage bacteria. M. bovis BCG is an attenuated non-pathogenic vaccine strain of M. bovis and the aim of the study was to determine the effect of the fermentation process on the survival of M. bovis BCG in milk. M. bovis BCG at concentrations of 6 log CFU/ml was added to products of kefir fermentation. The survival of M. bovis BCG was monitored at 12-h intervals for 72 h by enumerating viable cells on Middlebrook 7H10 agar plates enriched with 2% BD BACTEC PANTA™. M. bovis BCG was increasingly reduced in sterile kefir that was fermented for a period of 24h and longer. In the milk fermented with kefir grains, Lactobacillus paracasei subsp. paracasei or Lactobacillus casei, the viability of M. bovis BCG was reduced by 0.4 logs after 24h and by 2 logs after 48 h of fermentation. No viable M. bovis BCG was detected after 60 h of fermentation. Results from this study show that long term fermentation under certain conditions may have the potential to inactivate M. bovis BCG present in the milk. However, to ensure safety of fermented milk in Africa, fermentation should be combined with other hurdle technologies such as boiling and milk pasteurisation.
引起牛结核病（BTB）的牛分枝杆菌可通过食用患病动物的生乳和生发酵乳制品传播给人类。非洲流行的传统乳制品中使用的乳酸菌（LAB）会产生抑制某些致病和腐败细菌的抗菌化合物。卡介苗（M. bovis BCG）是牛分枝杆菌的减毒非致病疫苗株，该研究的目的是确定发酵过程对牛奶中卡介苗存活的影响。将浓度为6 log CFU/ml的卡介苗添加到开菲尔发酵产品中。通过在添加了2% BD BACTEC PANTA™的Middlebrook 7H10琼脂平板上计数活细胞，每隔12小时监测卡介苗的存活情况，持续72小时。在发酵24小时及更长时间的无菌开菲尔中，卡介苗数量逐渐减少。在用开菲尔粒、副干酪乳杆菌副干酪亚种或干酪乳杆菌发酵的牛奶中，发酵24小时后卡介苗的活力降低了0.4个对数，发酵48小时后降低了2个对数。发酵60小时后未检测到活的卡介苗。这项研究的结果表明，在某些条件下长期发酵可能有使牛奶中存在的卡介苗失活的潜力。然而，为确保非洲发酵乳的安全性，发酵应与其他栅栏技术如煮沸和牛奶巴氏杀菌相结合。
