Identification of commensal lactobacilli with immunomodulatory activities and inhibitory effects on Salmonella colonization in chickens

乳酸菌(LAB)是在哺乳动物和禽类的肠道中发现的一组微生物。包括乳酸菌在内的几个实验室已经被发现具有益生菌活性。一些乳杆菌是肠道微生物群落的正常成员，对宿主健康有好处。这些健康益处包括控制致病肠道微生物和增强宿主免疫反应，包括全身和局部肠道。在家禽业中，一些做法，如预防性使用抗生素，改变了肠道微生物群落的组成，并可能限制共生微生物控制致病微生物的能力，如沙门氏菌。事实上，家禽产品是人类食源性疾病的主要来源。在加拿大，沙门氏菌在2004年造成了约5,200例食源性疾病的报告病例，2001-02年度每个报告病例的平均估计费用为1,100美元。还应指出的是，根据一些估计，未报告的沙门氏菌病病例数量是报告病例数量的10倍。因此，家禽业迫切需要制定控制食源性致病菌从家禽传播到人类的策略。含有乳酸菌的益生菌提供了一种这样的策略。除了益生菌对肠道病原体的控制作用外，乳酸菌还具有免疫调节活性。然而，益生菌在鸡体内的免疫增强机制还没有得到深入的研究。更重要的是，目前可获得的具有已证实的鸡免疫增强能力的益生菌产品数量非常有限。因此，拟议的研究旨在筛选存在于鸡肠道微生物区系中的共生乳杆菌，以鉴定具有优越免疫调节活性的菌株。此外，我们打算评估这些细菌单独或联合使用在减少沙门氏菌对鸡肠道定植方面的效果。

Lactic acid producing bacteria (LAB) are a group of microbes that can be found in the intestines of mammals and avian species. Several LAB, including lactobacilli have been found to have probiotic activities. Some lactobacilli are normal members of the intestinal community of microbes and confer upon their host health benefits. These health benefits include control of disease-causing enteric microbes and enhancement of host immune response, both systemically and also locally in the intestine. In the poultry industry, some practices, such as the prophylactic use of antibiotics, alter the composition of the intestinal microbial community and may limit the ability of commensal microbes to control disease-causing microbes, such as Salmonella. In fact, poultry products are a major source of food-borne disease for humans. In Canada, Salmonella caused about 5,200 reported cases of food-borne illness in 2004, with an average estimated cost of $1,100.00 per reported case in 2001-02. It should also be noted that based on some estimates, the number of unreported cases of salmonellosis is 10 times higher than the number of reported cases. Therefore, it has become urgent for the poultry industry to develop strategies for control of transmission of food-borne pathoegens from poultry to humans. Probiotics containing lactobacilli offer one such strategy. In addition to the effects of probiotics on control of enteric pathogens, lactobacilli possess immunomodulatory activities in chickens. However, the immune enhancing mechanisms of probiotics in the chicken have not been studied in depth. More importantly, a very limited number of probiotic products are currently available with proven immune enhancing capabilities in chickens. Therefore, the proposed studies are aimed to screen commensal lactobacilli present in the chicken gut microbiota to identify isolates that have superior immunomodulatory activities. Furthermore, we intend to assess the efficacy of these bacteria either alone or in combination in reducing colonization of the chicken gut by Salmonella.