Biochar’s Adsorption of Escherichia coli and Probiotics Lactiplantibacillus plantarum and Limosilactobacillus reuteri and Its Impact on Bacterial Growth Post In Vitro Digestion

Background: Biochar has gained increasing attention for its potential benefits in improving animal health. Its physical and chemical properties depend on the starting biomass and production technology. This study investigates its functional properties versus bacteria. Methods: The morphology and physical properties of biochar from vine pruning were evaluated by SEM. The adsorption capacity for pathogenic E. coli F4+ and F18+ and probiotic microorganisms such as Lactobacillus sp. was assessed by plate count after contact with biochar. The growth activity on pathogenic and probiotic bacteria was tested after in vitro digestion. Results: Biochar from grapevine pruning did not maintain the original structure and showed both smooth and rough surfaces. The binding capacity varied across bacterial species. At concentrations of 20 mg/mL, up to 74% of E. coli adhered to the biochar surface, while the maximum adsorption rate of Lactobacillus sp. was around 38%. An inhibitory activity against E. coli (maximum reduction: 35%) and a growth-promoting effect for Lactobacillus sp. were observed (maximum promotion: 6%). Conclusions: These findings highlight the potential of biochar as a functional feed ingredient and that its functional properties are preserved after in vitro digestion.