What question did this study set out to answer?

This research aims to evaluate how Lactobacillus johnsonii DY2 from yaks can protect against acute E. coli infections.

February 2, 2026Veterinary Sciences0 citationsOpen Access

Lactobacillus johnsonii DY2 Isolated from Yaks Alleviated Acute Escherichia coli Infection via Modulating Inflammatory Responses, Antioxidant Capacity, and Gut Microbiota

YLYing LiuSouth China Agricultural University YDYanlei DongNanjing Agricultural University MSMuhammad SafdarHubei University of Arts and Science

Key Points

This research aims to evaluate how Lactobacillus johnsonii DY2 from yaks can protect against acute E. coli infections.
Isolated Lactobacillus johnsonii DY2 from yak feces.
Conducted in vitro tests to check the inhibitory effect on E. coli growth.
Administered DY2 orally to mice for 21 days before E. coli challenge.
Measured weight loss, bacterial translocation, organ indices, and immune responses pre- and post-infection.
Performed 16S rRNA sequencing to analyze gut microbiota diversity.
DY2 significantly reduced weight loss and bacterial translocation in treated mice (p < 0.001).
Normalized organ indices were observed in treated mice compared to controls (p < 0.05).
DY2 lowered pro-inflammatory cytokines and malondialdehyde levels (p < 0.001 to p < 0.05).
Increased anti-inflammatory IL-10 and antioxidant enzyme levels (p < 0.05 to p < 0.001).
Enhanced α-diversity and community stability of gut microbiota in DY2-treated mice (p < 0.05 to p < 0.001).

Abstract

The escalating challenge of antimicrobial resistance has spurred interest in probiotics as alternatives for combating bacterial infections. This study aimed to isolate and characterize probiotic Lactobacillus johnsonii (L. johnsonii) from yak feces with protective efficacy against acute Escherichia coli (E. coli) infection. In vitro, DY2 supernatant inhibited the growth of E. coli. In vivo, mice pretreated orally with DY2 (1 × 109 CFU/mL) for 21 days before E. coli challenge exhibited significantly reduced weight loss (p < 0.001), lower bacterial translocation in the intestines (p < 0.001), and normalized organ indices (p < 0.05) compared to untreated infected controls. DY2 modulated host immune and oxidative responses by significantly lowering serum levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6; p < 0.001 to p < 0.05) and malondialdehyde (MDA; p < 0.001), while elevating levels of the anti-inflammatory IL-10 (p < 0.05) and antioxidant enzymes (SOD, GSH-Px, T-AOC; p < 0.001 to p < 0.01). Histologically, DY2 preserved intestinal mucosal integrity, with reduced villus shortening and inflammatory infiltration (p < 0.001 for villus length in key segments). 16S rRNA sequencing of intestinal microbiota revealed enhanced α-diversity (p < 0.05 to p < 0.001), community stability, and enrichment of beneficial genera such as Butyricimonas in DY2-treated mice. Conclusively, Lactobacillus johnsonii DY2 protects against acute E. coli infection via anti-inflammatory, antioxidant, gut barrier strengthening, and microbiota-modulating activities. Yak-derived lactobacilli are promising probiotics with excellent antibacterial properties.

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