Fernandez Benoît, Savard Patricia, Fliss Ismail
STELA Dairy Research Center, Nutrition and Functional Foods Institute, Université Laval, G1K 7P4, Québec, QC, Canada.
Microb Ecol. 2016 Nov;72(4):931-942. doi: 10.1007/s00248-015-0645-0. Epub 2015 Jul 11.
Pediococcus acidilactici UL5 is a promising probiotic candidate due to its high survival rate under gastric and duodenal conditions and to its ability to produce the antilisterial bacteriocin pediocin PA-1. Its survival, metabolic activity, and impact on Listeria monocytogenes in a continuous stirred tank reactor containing immobilized human intestinal microbiota were studied over a period of 32 days of feeding a nutrient medium simulating ileal chyme. The impact of P. acidilactici UL5 on different bacterial groups of intestinal origin as well as its survival and its impact on L. monocytogenes were quantified using quantitative polymerase chain reaction coupling with propidium monoazide (PMA-qPCR), which was shown to detect and quantify viable bacteria only. P. acidilactici UL5 and its non-pediocin-producing mutant had no effect on the microbiota, but the producing strain induced an increase in the production of acetic and propionic acids. P. acidilactici survived but appeared to be a poor competitor with intestinal microbiota, dropping by 1.3 and 2.8 log after 8 h of fermentation to 10 colony-forming units (cfu) mL. A 1.64 log but non-significant reduction of Listeria was observed when P. acidilactici UL5 was added at 10 cfu mL. P. acidilactici UL5 isolated from the reactor after 3 days was still able to produce the active bacteriocin. These data demonstrate that P. acidilactici UL5 is capable of surviving transit through the ileum without losing its ability to produce pediocin PA-1 but seems to not be enough competitive with the great diversity of organisms found in the ileum.
嗜酸乳杆菌UL5是一种很有前景的益生菌候选菌株,因为它在胃和十二指肠条件下具有较高的存活率,并且能够产生抗李斯特菌的细菌素——植物乳杆菌素PA-1。在连续搅拌罐式反应器中,固定化的人类肠道微生物群在32天的时间里被投喂模拟回肠食糜的营养培养基,期间研究了嗜酸乳杆菌UL5的存活率、代谢活性及其对单核细胞增生李斯特菌的影响。使用定量聚合酶链反应结合单叠氮丙锭(PMA-qPCR)对嗜酸乳杆菌UL5对不同肠道来源细菌群的影响以及其存活率和对单核细胞增生李斯特菌的影响进行了量化,结果表明该方法只能检测和量化活细菌。嗜酸乳杆菌UL5及其不产生植物乳杆菌素的突变体对微生物群没有影响,但产生菌株可诱导乙酸和丙酸产量增加。嗜酸乳杆菌能够存活,但似乎与肠道微生物群的竞争力较弱,发酵8小时后下降了1.3和2.8个对数,降至10个菌落形成单位(cfu)/mL。当嗜酸乳杆菌UL5以10 cfu/mL添加时,观察到李斯特菌有1.64个对数的下降,但不显著。3天后从反应器中分离出的嗜酸乳杆菌UL5仍能够产生活性细菌素。这些数据表明,嗜酸乳杆菌UL5能够在通过回肠的过程中存活下来,而不会丧失产生植物乳杆菌素PA-1的能力,但似乎与回肠中发现的种类繁多的生物体相比竞争力不足。