猪源性产细菌素乳酸菌对猪肠道菌群结构影响的研究

Bacteriocins, secrered by bacteria with high effect on inhibiting other strains or species, are a category of bactericidal peptides.In the primary study,five high production of bacteriocin lactic acid bacteria stains were isolated from porcine intestinal contents in our lab.More studies showed that this strain was good at inhibiting of many pig original pathogenic Escherichia coli and salmonella. In this study, bacteriocinogenic latic acid strains will be co-cultured with the common pathogenic bacteria and commensal bacteria of pigs in vitro and in vivo to investigate the interaction between the bacteriocinogenic strain and co-cultural strains. The bacteriocin products will also be isolated and purified to check their potency in anti pathogenic bacteria and inner bacteria. Based on the results of these experiments, the possible gastrointestinal flora structure regulatory mechenism by bacteriocinogenic lactic acid bacteria will be proposed and illustrated.This study will investigate into the way using bacteriocinogenic bacterium producing bacteriocin " on site" to prevent and cure bacterial diseases in animals. These results can also benefit the explanation of using bacterions in control of enteric bacteria steady state and the development of feed viable bacteriocinogenic probiotics.

细菌素是一类由细菌分泌的对其它细菌具有抑杀作用的多肽或蛋白类物质。本实验室前期从猪肠道内容物中分离获得5株高产细菌素的乳酸菌，研究发现其对临床分离的多株猪源致病性大肠杆菌、沙门氏菌均有极佳的抑杀作用。本研究将通过该高产细菌素的乳酸菌在猪体内和体外分别与猪肠道正常菌群及常见临床分离致病菌进行对峙培养，研究高产细菌素的乳酸菌对猪肠道菌群结构的调节作用。同时对所产细菌素进行分离纯化，研究所产细菌素对猪肠道内正常菌群的调控作用，阐明产细菌素乳酸菌对猪肠道菌群结构调节的可能作用机制。探索利用高产细菌素菌株在动物体内"现场"生产细菌素来实现利用细菌素防治动物细菌性疾病的途径，为利用细菌素调控动物肠道菌群及开发可用于饲料添加的产细菌素菌株作为益生素提供科学参考。

随着抗生素在畜牧业中应用的逐渐减少甚至禁用，新的抗生素替代物亟待被开发出来。从动物肠道中分离能产具有抗致病菌活性的内生菌株，通过其抑菌活性产物或者自身活动来调节动物肠道正常菌群，从而达到维持动物健康，促进动物生长的目的，是实现抗生素替代的一种理想策略。本项目通过对前期从猪肠道分离获得的抑菌活性内生菌株所产抑菌活性产物的分离、纯化及鉴定，从分子水平上阐明其抑菌活性产物的构成，同时分别对该抑菌活性产物及该活性菌株本身对猪肠道内的正常菌群及常见致病菌进行了抑菌活性检测，从而对该活性菌株及该菌株所产抑菌活性产物用于动物生产中可能导致动物肠道菌群发生的变化进行了研究。最后，为了进一步有效地利用该活性菌株及其抑菌活性产物，本研究还对该菌株生产该抑菌活性产物的条件进行了优化。研究结果表明，该活性菌株生产的抑菌活性产物是脂肽Surfactin、Iturin和Fengycin的复合物。该复合物对李斯特氏菌、变形杆菌、大肠杆菌等临床分离的致病菌具有抑菌活性，而对肠道分离的乳酸杆菌等没有抑菌活性。利用对峙培养试验的结果表明，该活性菌株对临床分离的金黄色葡萄球菌、大肠杆菌、沙门氏菌等均有良好的抑菌活性，可对外源性致病菌起到一种防御作用。综合以上结果，表明该活性菌株及其抑菌活性产物均对动物肠道内的菌群具有一定的调节作用，可进一步作为肠道菌群调节剂或益生菌来开发。