ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Food Microbiology
This article is part of the Research TopicProbiotic Potential: Lactic Acid Bacteria in Advancing Functional Foods and Health OutcomesView all 16 articles
Bactericidal and antibiofilm activity of lactic acid bacteria-derived cell free extracts against dairy-associated spoilage and pathogenic bacteria
Provisionally accepted
Andressa Falqueto1
Luana Virginia Souza2
Rafaela Da Silva Rodrigues2Cinzia Caggia3Antonio Fernades de Carvalho1
Luis Augusto Nero2Solimar Gonçalves Machado1
Cinzia Lucia Randazzo3*- 1Departamento de Tecnologia de Alimentos, Universidade Federal de Vicosa, Viçosa, Brazil
- 2Departamento de Medicina Veterinária, Universidade Federal de Vicosa, Viçosa, Brazil
- 3Department of Agriculture, Food and Environment, University of Catania, Catania, Italy
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This study aimed to evaluate the antimicrobial and antibiofilm potential of fifteen LAB strains using five types of LAB-derived preparations: cell-free supernatants (CFS), sonicated-inactivated cells (IC), their combination (ICS), and their neutralized variants (CFS N, ICS N) to identify the most effective strain-extract combinations for potential application as natural biocontrol agents in dairy systems. Antimicrobial activity was assessed through agar diffusion assays, growth and biofilm inhibition, and determination of minimum inhibitory (MIC) and bactericidal (MBC) concentrations. The extracts were further characterized by pH and organic acid profiles using high-performance liquid chromatography (HPLC), and their mechanisms of action were investigated through cellular leakage assays, time–kill kinetics, and scanning electron microscopy (SEM). Several LAB-derived extracts exhibited strong antagonistic and antibiofilm activity against both spoilage and pathogenic bacteria. Non-neutralized CFS and ICS showed pronounced bactericidal activity, confirming the central role of organic acids in microbial inhibition. Z-score ranking and leakage assays identified Lactiplantibacillus plantarum Q4C3, Lactococcus lactis subsp. lactis biovar diacetylactis SBR4, Weissella cibaria W21, and Weissella viridescens W23 as the most effective strains. Time–kill assays demonstrated rapid microbial reductions (>3 log CFU/mL) within 4h by CFS, whereas ICS required longer exposure. SEM analysis revealed severe membrane disruption in CFS-treated cells and the presence of LAB-derived debris surrounding ICS-exposed cells. These findings demonstrate that acidic LAB-derived extracts, particularly CFS, efficiently disrupt microbial cells and support their use as safe and effective natural biocontrol agents for improving the microbial safety and quality of dairy products.
Keywords: bacterialmembrane disruption5, Biopreservative4, Food Safety2, Food spoilage1, growth inhibition6, Organic acid profile3
Received: 08 Jan 2026; Accepted: 11 Feb 2026.
Copyright: © 2026 Falqueto, Souza, Rodrigues, Caggia, de Carvalho, Nero, Machado and Randazzo. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Cinzia Lucia Randazzo
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