Enzymatic dispersion of pseudomonad biofilms grown at psychrotrophic temperature

Pseudomonads are robust biofilm formers in psychrotrophic temperatures, which can cause spoilage in dairy, poultry, and meat processing. This study screened eleven isolates for the biofilm-forming ability using the Congo Red Assay (CRA) and the crystal violet assay. Two isolates, 3SM and 20SM, showed significantly higher EPS production, cellulose synthesis and cell count at 4ºC and were selected for the enzymatic dispersion. Mature biofilms formed on the stainless-steel surface for 72 h at 4°C were treated with laboratory enzymes (Proteinase-K, Cellulase, and DNase I) and commercial enzymes (formulated cleaners, EnduroZyme, DualZyme, and TriZyme). Compared to laboratory enzymes, commercial enzymes were efficient in dispersing the biofilms (EnduroZyme- 62 %, DualZyme- 42 %, and TriZyme-32 % of biofilm removal), which was confirmed by cell counts, crystal violet assay, and microscopic observations. However, none of the treatments resulted in complete biofilm dispersion. These findings highlight the resilience of psychrotrophic pseudomonad biofilms and underscore the need for improved enzymatic strategies tailored for cold-chain environments. • P. lundensis and P. cedrina form robust biofilms at 4ºC. • The laboratory enzymes reduced the biofilm cell counts by less than a log CFU/cm 2 . • The commercial enzyme cleaners reduced the biofilm biomass from 32 % to 62 %.