Vol. 10, Issue 12, Part A (2025)

Author(s): Naveen Kumar TJ, K Radha, VN Vasudevan, Sathu T, R Geetha, K Vrinda Menon and Gleeja VL

Abstract: Biofilm-associated contamination by Pseudomonas and Bacillus remains a major challenge in dairy processing environments, necessitating natural and effective antimicrobial alternatives. This study evaluated the antimicrobial and antibiofilm efficacy of a postbiotic preparation derived from Lacticaseibacillus paracasei UBLP-35 against these predominant dairy-associated spoilage organisms. The postbiotic was produced through heat inactivation, ultrasonic lysis and lyophilization, yielding a cell-free bioactive preparation. Antimicrobial activity assessed by agar disc diffusion demonstrated a strong, concentration-dependent inhibitory effect (P=0.001). Pseudomonas aeruginosa inhibition zones increased from 6.60±0.15 mm at 300 mg/mL to a maximum of 13.93±0.28 mm at 900 mg/mL, while Bacillus inhibition expanded from 7.23±0.10 mm to 16.15±0.41 mm over the same concentration range. Antibiofilm assays revealed substantial suppression of biofilm formation, with optical density values decreasing significantly at higher postbiotic concentrations (P=0.001). At 900 mg/mL, biofilm biomass was reduced to 0.043±0.002 in P. aeruginosa and 0.032±0.001 in Bacillus subtilis, corresponding to 78.71 and 72.41 per cent inhibition, respectively. Lower concentrations (300-800 mg/mL) also produced graded reductions, confirming a clear dose-response trend. Overall, the results demonstrate that L. paracasei-derived postbiotics exhibited potent, broad-spectrum antimicrobial and antibiofilm activities. The high efficacy at ? 800 mg/mL highlights the potential of this postbiotic as a clean-label biopreservative for mitigating biofilm-mediated spoilage in dairy processing systems. These findings support the industrial applicability of LAB postbiotics as stable, natural and safe interventions for enhancing microbial safety and extending product shelf life.

DOI: 10.22271/veterinary.2025.v10.i12a.2783