AUTHOR=Wang Jing , Zeng Yanxia , Wang Sixin , Liu Hui , Zhang Dongyan , Zhang Wei , Wang Yamin , Ji Haifeng 

TITLE=Swine-Derived Probiotic Lactobacillus plantarum Inhibits Growth and Adhesion of Enterotoxigenic Escherichia coli and Mediates Host Defense

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.01364

DOI=10.3389/fmicb.2018.01364

ISSN=1664-302X

ABSTRACT=<p>Weaning stress renders piglets susceptible to pathogen infection, which leads to post-weaning diarrhea, a severe condition characterized by heavy diarrhea and mortality in piglets. Enterotoxigenic <italic>Escherichia coli</italic> (ETEC) is one of typical strains associated with post-weaning diarrhea. Thus, prevention and inhibition of ETEC infection are of great concern. Probiotics possess anti-pathogenic activity and can counteract ETEC infection; however, their underlying mechanisms and modes of action have not yet been clarified. In the present study, the direct and indirect protective effects of <italic>Lactobacillus plantarum</italic> ZLP001 against ETEC infection were investigated by different methods. We found that bacterial culture and culture supernatant of <italic>L. plantarum</italic> ZLP001 prevented ETEC growth by the Oxford cup method, and ETEC growth inhibition was observed in a co-culture assay as well. This effect was suggested to be caused mainly by antimicrobial metabolites produced by <italic>L. plantarum</italic> ZLP001. In addition, adhesion capacity of <italic>L. plantarum</italic> ZLP001 to IPEC-J2 cells were observed using microscopy and counting. <italic>L. plantarum</italic> ZLP001 also exhibited a concentration-dependent ability to inhibit ETEC adhesion to IPEC-J2 cells, which mainly occurred via exclusion and competition mode. Furthermore, quantitative real time polymerase chain reaction (qPCR) analysis showed that <italic>L. plantarum</italic> ZLP001 upregulated the expression of host defense peptides (HDPs) but did not trigger an inflammatory response. In addition, <italic>L. plantarum</italic> ZLP001 induced HDP secretion, which enhanced the potential antimicrobial activity of IPEC-J2 cell-culture supernatant after incubation with <italic>L. plantarum</italic> ZLP001. Our findings demonstrate that <italic>L. plantarum</italic> ZLP001, an intestinal <italic>Lactobacillus</italic> species associated with piglet health, possesses anti-ETEC activity. <italic>L. plantarum</italic> ZLP001 might prevent ETEC growth, inhibit ETEC adhesion to the intestinal mucosa, and activate the innate immune response to secret antimicrobial peptides. <italic>L. plantarum</italic> ZLP001 is worth investigation as a potential probiotics.</p>