Gastric Postbiotics Show Promise Against Biofilm Infections

Postbiotics derived from bacteria naturally found in the human stomach demonstrated potent antimicrobial and anti-biofilm activity against two clinically important pathogens in a new study. The findings suggest these non-living microbial products could represent a promising alternative to conventional antimicrobials in the fight against biofilm-associated infections.

As antimicrobial resistance continues to increase, researchers are exploring alternatives to traditional antibiotics. Unlike probiotics, which contain live microorganisms, postbiotics are preparations of inactivated microbes or their metabolites. Because they do not contain viable bacteria, postbiotics may offer advantages including improved stability, longer shelf life, and a potentially lower risk of adverse effects, particularly in vulnerable patient populations.

Researchers Isolated Beneficial Gastric Bacteria

The study began by analysing gastric biopsy samples from 20 patients with gastritis to identify bacteria with probiotic characteristics.

Researchers recovered 65 bacterial isolates, most of which were Gram-positive bacilli. Following safety screening, 34 isolates underwent further testing for survival under conditions resembling the human stomach.

Two isolates demonstrated particularly favourable probiotic characteristics, including survival in acidic conditions, resistance to bile salts, strong adhesion to intestinal epithelial cells, and persistence in simulated gastric juice. Genetic sequencing identified the strains as belonging to the Lacticaseibacillus and Ligilactobacillus genera.

The researchers subsequently produced postbiotic preparations from these isolates, designated PQ3 and PM2.

Strong Activity Against Bacterial and Fungal Pathogens

Both postbiotic preparations inhibited the growth of Staphylococcus aureus and Candida albicans, two pathogens frequently associated with difficult-to-treat biofilm infections.

PM2 consistently demonstrated greater antimicrobial activity than PQ3, requiring lower concentrations to inhibit or kill both organisms. The findings indicate that metabolites produced by certain gastric bacteria may possess broad-spectrum antimicrobial properties against both bacterial and fungal pathogens.

Biofilm Formation Significantly Reduced

In addition to inhibiting microbial growth, both postbiotics disrupted biofilm formation.

PQ3 reduced S. aureus biofilms by up to 49% and C. albicans biofilms by up to 51%. PM2 produced even greater effects, reducing bacterial biofilms by as much as 74% and fungal biofilms by up to 85%.

Because biofilms protect microorganisms from antimicrobial agents and immune responses, therapies capable of disrupting these structures could improve the management of chronic and device-associated infections.

Potential Alternative to Conventional Antimicrobials

The authors conclude that gastric microbiota-derived postbiotics represent promising candidates for future antimicrobial development.

While the findings are limited to laboratory experiments, they demonstrate that bioactive compounds produced by naturally occurring gastric bacteria can inhibit both microbial growth and biofilm formation. The researchers suggest that further in vivo studies, alongside genomic and mechanistic investigations, will be needed to determine how these postbiotics exert their antimicrobial effects and whether they can be translated into clinically useful therapies.

As interest in microbiome-based therapeutics continues to grow, postbiotics may emerge as an important addition to strategies aimed at tackling antimicrobial resistance while reducing reliance on conventional antibiotics.

Reference

Azizi M et al. Gastric microbiota‑derived postbiotics as antimicrobial and anti‑biofilm agents. BMC Microbiol. 2026;DOI: 10.1186/s12866-026-05429-2.