Probiotic and antibacterial properties of recombinant Lactococcus lactis expressing the fusion antimicrobial peptides BMAP18-BSN37 in mice and chickens.

Study Design

Population: BALB/c murine and 817 strain avian models
Methods: A recombinant food-grade strain, L. lactis NZ-BB, was engineered to express a fusion antimicrobial peptide (BMAP18-BSN37) and evaluated in vivo; oral administration trials with Nisin-induced peptide expression were performed

Animal Study

Antimicrobial resistance poses a serious threat to global food safety and poultry production, prompting the need for effective alternatives to conventional antibiotics in food-producing animals. In this study, a recombinant food-grade strain, L. lactis NZ-BB, was engineered to express a fusion antimicrobial peptide (BMAP18-BSN37), and evaluated its probiotic characteristics and antimicrobial efficacy against Salmonella, a major foodborne pathogen in chicken. The recombinant plasmid pUBB was successfully constructed and introduced into L. lactis NZ9000, with optimal peptide expression achieved following Nisin induction (20 ng/mL, 6 h). NZ-BB demonstrated stable plasmid maintenance, high expression levels, and no detectable metabolic burden. In vivo trials using BALB/c murine and 817 strain avian models showed that NZ-BB enhanced body weight gain, supported immune organ development, and improved intestinal barrier integrity through upregulation of tight junction proteins (occludin, claudin-1, ZO-1) and anti-inflammatory cytokines (TGF-β, IL-4), while reducing pro-inflammatory markers (IL-1β, TNF-α, IL-17a). Importantly, oral administration of NZ-BB significantly reduced intestinal and systemic Salmonella burdens, mitigated tissue damage, and restored immune balance in both mice and chicks. Furthermore, NZ-BB regulated the expression of innate immune receptors (e.g., NLRC3) and matrix metalloproteinases (e.g., MMP-1), highlighting its immunomodulatory potential. These results underscore the dual probiotic and antimicrobial functionality of NZ-BB and support its potential use as a food-safe microbial agent to improve animal health and reduce the risk of Salmonella contamination in the food chain.

Research Insights

Supplement	Dose	Health Outcome	Effect Type	Effect Size	Source
Lactobacillus lactis LI-23	—	Improved Growth Performance	Beneficial	Moderate	View source NZ-BB enhanced body weight gain, supported immune organ development
Lactobacillus lactis LI-23	—	Improved Intestinal Barrier Function	Beneficial	Moderate	View source NZ-BB enhanced body weight gain, supported immune organ development, and improved intestinal barrier integrity through upregulation of tight junction proteins (occludin, claudin-1, ZO-1) and anti-inflammatory cytokines (TGF-β, IL-4)
Lactobacillus lactis LI-23	—	Reduced Intestinal Inflammation	Beneficial	Moderate	View source while reducing pro-inflammatory markers (IL-1β, TNF-α, IL-17a)
Lactobacillus lactis LI-23	—	Reduced Salmonella Colonization	Beneficial	Large	View source oral administration of NZ-BB significantly reduced intestinal and systemic Salmonella burdens, mitigated tissue damage, and restored immune balance in both mice and chicks