Study On The Isolation And Identification Of Lactobacillus Amylovorus And Enterococcus Faecalis And Its Application In Weaned Piglets

The aim of this study was to isolate symbiosis and intermediate strains from the growing pig's ileum,colon and cecum,and to study the physiological and biochemical tests in vitro.The Lactobacillus amylovorus(LA)and Enterococcus faecalis(EF)with high nitrigon utilization were choosed to study the effects of LA and EF on the performance,immune function,antioxidant function and microflora of weanling piglets were studied.This paper includes the following two parts:Study content 1: A 60-d growthing pig was selected for the experiment,and the contents of ileum,colon and cecum were collected aseptically.After incubation at 37oC for 24 h,the morphological changes were observed under microscope.The DNA was extracted according to different morphologies and the DNA was extracted for16 sRNA sequencing.Lactobacillus amylovorus(LA),Lactobacillus reuteri,Enterococcus faecalis(EF)and Escherichia coli were isolated and identified.In vitro,the results showed that Lactobacillus amyloliquefaciens(LA)and Enterococcus faecalis(EF)were resistant to acid,high temperature resistance,high copper resistance and antibacterial properties.At the same time,the two probiotics had the activity of decreasing the activity of decarboxylase.Study content II: Based on the results of sdudy content 1,to further study LA and EF in weaned piglets on the application of the effect and the probiotic mechanism.A total of 40 healthy weaned pigs were randomly divided into four groups(each treatment had 10 replicates,each replicate had 1 piglet,each piglet was kept in individual pen): control(CON)group;Lactobacillus amylovorus(LA)group(1 ×1010CFU,3 times a day);Enterococcus faecalis(EF)group(1×1010 CFU,3 times a day),Lactobacillus amylovorus +Enterococcus faecalis(LA+EF)(1×1010 CFU/each strain,3 times a day).The results showed that oral LA and EF significantly improved the end-weight,average daily feed intake,average daily gain and feed conversion rate of piglets(P<0.05).LA increased significantly thymus index,pancreas dirty index,spleen index,lymph node index and jejunum length index(P<0.05).The activity of T-SOD and GSH-PX was significantly increased(P<0.05),and the activity of MDA was significantly decreased(P>0.05)after oral administration of LA and EF.LA and EFsignificantly reduced the pH of piglets(P<0.05).The expression of ?-defensin-2 and TLR4(P<0.05)significantly increased the expression of HSP90(P<0.05).The expression of ?-defensin-2 and TLR4 was significantly increased(P<0.05),significantly reduced the activity of lysine decarboxylase,methionine decarboxylase,threonine decarboxylase,and lysine in the colon microbes.The effect of Lactobacillus amylovorus and Enterococcus faecalis on the decarboxylase activity of intestinal microbes was significant(P<0.05)Amino acid decarboxylase,ornithine decarboxylase and histidine decarboxylase(P<0.05).Two probiotics did not alter the dominant colonies within the colon,but increased the relative abundance of microbes in the colon.Lactobacillus amylovorus reduced the abundance of Enterobacter cloacae and Clostridium in cecum,and increased the relative abundance of lactic acid bacteria,Velvetia and Rhizoctonia.In summary,Lactobacillus amylovorus and Enterococcus faecalis have improved animal production performance,improve the body immunity,protect the liver.Without changing the composition of intestinal dominant flora at the same time,improve the abundance of some beneficial bacteria in the colon,reducing the abundance of some harmful bacteria,played a role in maintaining intestinal microflora.Therefore,it can be considered as an additive in pig production applications.At the same time,we found that the combination of the two probiotics was similar to that of Lactobacillus amylovorus alone.Therefore,we can choose to add Lactobacillus amylovorus alone in the production,which not only achieves the purpose of healthy breeding,but also saves the cost.