Integrative Phenotypic and Genomic Analysis Reveals Antimicrobial and Stress-Resistance Mechanisms of Lacticaseibacillus rhamnosus MG0718 as a Promising Probiotic Candidate for Food Applications.

Lactobacilli species have emerged as a focal point in food microbiology due to their core probiotic properties, including the regulation of intestinal homeostasis and the enhancement of immunity. This study focuses on Lacticaseibacillus rhamnosus MG0718 (hereinafter referred to as MG0718), employing a combined approach of phenotypic evaluation and whole-genome sequencing to assess its probiotic potential and analyze the correlation between its phenotype and genotype. In vitro experiments demonstrated that MG0718 possesses broad-spectrum antibacterial activity against pathogenic bacteria. In vitro experiments showed that MG0718 had broad-spectrum antibacterial activity against pathogenic bacteria such as Escherichia coli (E. coli), with an inhibition zone diameter of up to 13.67 ± 1.56 mm. It survived pH 2.5 for 6 h with only a 1.72 log10 reduction, and showed 0.78 and 1.11 log10 CFU/mL reductions in artificial gastric and intestinal fluids after 2 h. DPPH scavenging was 56.7% and total reducing power was 91.1%. In vivo, 7-day preventive administration maintained 100% survival against S. Typhimurium infection and alleviated weight loss. Bacterial loads in spleen, liver, and cecum dropped from 4.5, 4.5, and 4.2 to 3.6, 1.8, and 2.5 lg CFU/g, respectively. Whole-genome sequencing analysis indicated that the complete genome of MG0718 is 2,574,565 bp in length, containing 2813 CDS. Among these genomic components, 203 stress-related protein genes elucidate its superior environmental tolerance; one bacteriocin gene cluster, one EPS gene cluster and two secondary metabolite gene clusters provide the genetic basis for its antibacterial activity. Notably, no virulence factors were detected, ensuring the safety of the strain for application. In summary, the functional phenotypes of MG0718 are highly consistent with its genetic characteristics, identifying it as a probiotic candidate of significant developmental value. Future research should focus on clinical trials to further verify its practical benefits for human intestinal health and immunomodulation, thereby providing a robust scientific basis for its application in functional foods.