Recombinant lactobacillin PlnK adjusts the gut microbiome distribution in broilers

1. The heterologous expression and biological function of the Lactobacillus bacteriocin plantaricin K (PlnK) remain largely unknown. 2. In this study, PlnK was efficiently expressed in competent <i>E. coli</i> BL21 (used in transformation and protein expression) after 12 h, at 37°C and in 0.4 mmol/l isopropyl β- d-1-thiogalactopyranoside (IPTG). 3. The inhibitory bacterial spectrum of recombinant PlnK was investigated and indicated that levels of PlnK above 0.10 mg/ml produced an obvious inhibitory effect on gram-positive bacteria and gram-negative bacteria <i>in vitro</i>. 4. The effects of PlnK on intestinal immune function and the gut microbiome distribution in broilers were studied. The results revealed that, after consuming 2.50 × 10^˗3 mg/ml of PlnK in water for one week, at the phylum level, the abundance of <i>Firmicutes</i> was increased and the abundance of <i>Bacleroidetes</i> was decreased. At the family level, the abundance of <i>Lachnospiraceae, Ruminococcaceae</i> and <i>Streptococcaceae</i> were significantly improved, but the abundance of <i>Bacteroidaceae</i> was reduced. At the genus level, the abundances of <i>Lachnoclostridium, Streptococcus</i> and <i>Ruminococcaceae</i>-UCG-013, were significantly up-regulated, and the abundance of <i>Bacteroides</i> was down-regulated. 5. After oral liquid intake of PlnK for one week, levels of secretory immunoglobulin A (sIgA) in the duodenal mucus were not significantly increased, but the mRNA levels of <i>TLR</i>3, <i>MDA</i>5, <i>IFN-α, IFN-β, IFITM</i>3 and <i>IFITM</i>10 in the duodenum were significantly reduced. 6. This study demonstrated that the recombinant PlnK could adjust the intestinal microbiome distribution and downregulate the IFN pathway.