Enzymatic Dispersion of Pseudomonad Biofilms Grown at Psychrotrophic Temperature

Abstract Pseudomonads are robust biofilm formers in psychrotrophic temperatures, which can cause spoilage in dairy, poultry, and meat processing. This study screened strong biofilm formers based on the Congo Red Assay (CRA) and crystal violet assay. Among the eleven dairy isolates, two isolates, 3SM and 20SM, were strong biofilm formers at 4°C based on the crystal violet assay. With CRA, these two isolates were identified as cellulose producers. The cellulose quantification results agreed with the CRA. These two isolates produced significantly higher EPS and cell counts at 4°C compared to the other isolates. The strong biofilm-forming isolates were allowed to form biofilms on a stainless-steel surface for 72 h at 4°C. The preformed biofilms were treated with both laboratory (pure chemicals such as 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, complete dispersion was not achieved. This indicated the need for further research to improve the efficacy of enzyme cleaners in pseudomonad biofilm removal.