Probiotic Lactobacillus casei expressing porcine antimicrobial peptide PR39 elevates antibacterial activity in the gastrointestinal tract

Abstract

PR39, a 4.7 kDa proline-rich antimicrobial peptide, acts as a cationic host defense peptide. In addition to killing bacteria, PR39 mediates inflammatory reactions, including cell proliferation, migration, wound healing, and angiogenesis. Here, we examined the antibacterial effects of this peptide. The synthetic gene fragment PR39 was inserted into the secretory expression vector plasmid pPG:612 of Lactobacillus casei, yielding the recombinant strain pPG:612-PR39/L. casei 393. In vitro antibacterial tests showed that expression of the PR39 peptide in recombinant L. casei resulted in antibacterial activity against Escherichia coli and Salmonella but had only minor antibacterial effects in Staphylococcus aureus. In addition, BALB/c mice fed the recombinant pPG:612-PR39/L. casei 393 grew better and had increased peripheral blood lymphocyte percentages, white blood cell numbers, and spleen indices than mice in the control group. Scanning electron microscopy showed that jejunum and duodenum villus height, crypt depth, and the ratio of villus height/crypt depth in the intestinal villi also increased. Moreover, mice fed the recombinant strain showed significantly lower mortality rates than the control group mice when challenged with the enterotoxigenic E. coli K88. Thus, this recombinant expression system had the beneficial characteristics of both L. casei and PR39, supporting its potential as an animal feed additive.

A bovine lactoferricin-lactoferrampin-encoding Lactobacillus reuteri CO21 regulates the intestinal mucosal immunity and enhances the protection of piglets against enterotoxigenic Escherichia coli K88 challenge

“…14 The synthesis and purification of AMPs are costly and timeconsuming. 15 Lactobacillus has been considered a good delivery vehicle to express AMPs for preserving the mucosal integrity, improving intestinal microbiota and ameliorating DSS-induced intestinal injury. 16,17 In this sense, AMPs serves as a strategy to provide protection against ETEC colonization and infection.…”

Dietary supplementation of recombinant antimicrobial peptide Epinephelus lanceolatus piscidin improves growth performance and immune response in Gallus gallus domesticus

“…Moreover, growth enhancement has been observed in other reports [37,38]. For example, feeding mice with PR39 peptide (4.7 kDa proline-rich AMP)-expressing Lactobacillus casei caused jejunum and duodenum villus height in the intestinal villi to increase [39]. Use of recombinant porcine β-defensin 2 (rpBD2) as a feed additive for weaned piglets also produced increases in intestinal villus height of the duodenum and jejunum [40].…”

Effects of Lactococcus lactis MG1363 producing fusion proteins of bovine lactoferricin–lactoferrampin on growth, intestinal morphology and immune function in weaned piglet

“…Staphylococcus aureus CVCC 25923, E. coli CVCC 10141 and Salm. enteritidis CICC 21482 were used to test the antibacterial activity of the LFCA using the previously described assay procedure (Lei Zhang et al, ). Briefly, 15 μmol l −1 LFCA protein (concentrated culture supernatant of pAMJ399‐LFCA/LLMG1363) was added to the LB broth containing approximately 1 × 10 6 CFU per ml of each bacterial strain and incubated at 37°C for 6 h. Moreover, L. pentosus KLDS1·0413 was first grown in the MRS broth, and then transferred to the MRS broth containing 15 μmol l −1 LFCA and incubated for 6 h. The optical density of the culture was determined every 1 h at an absorbance wavelength of 600 nm.…”