Reuterin inhibits Pseudomonas spp. growth and biofilm formation, and extends fresh cheese shelf life

Pseudomonas spp. cause texture, flavour and colour defects in milk and fresh cheese, and are commonly associated with post-pasteurization contamination due to their ability to form biofilms. Current strategies to prevent these defects reduce, but do not avoid, Pseudomonas contamination. In this work, the antimicrobial potential of reuterin, produced by Limosilactobacillus reuteri INIA P572, against 10 dairy Pseudomonas strains was investigated. These strains were selected for their spoilage potential and/or biofilm-forming ability. Reuterin showed a broad anti-pseudomonas spectrum in trypticase soy broth (TSB), inhibiting the growth of all Pseudomonas strains and preventing biofilm formation at refrigeration (6 °C) and room temperature (25 °C). Additionally, reuterin minimum bactericidal concentrations ranged from 8.64 to 30.22 mM, except for P. fluorescens INIA Ps146, which was not eradicated by the highest tested concentration. Fresh cheeses inoculated with these Pseudomonas strains showed discoloration after 5 days of refrigerated storage. However, when fresh cheeses were pre-treated with a 69 mM reuterin solution before inoculation, no colour defects were observed after 28 days for four strains, while for the other six strains, the defect was delayed by 9–23 days. These results suggest that reuterin may be a promising biopreservative to control Pseudomonas in dairy products. • Pseudomonas causes texture, flavour and colour defects in milk and fresh cheese. • Reuterin showed a broad anti-pseudomonas spectrum, inhibiting all strains tested. • Reuterin had a bactericidal effect on 9 of the 10 Pseudomonas strains tested. • Reuterin prevented the formation of biofilms by all Pseudomonas strains. • Reuterin delayed the colour defects caused by Pseudomonas in fresh cheese.