Yeast biofilm development and rheological properties on turbluent flow regimes

BRUGNONI, LORENA INÉS; TARIFA, MARÍA CLARA; LOZANO, JORGE ENRIQUE; GENOVESE, DIEGO BAUTISTA

Maastricht

Congreso; 6th Congress of European Microbiologists; 2015

BackgroundIn food processing lines or in complex equipment, microorganisms are exposed to varying hydrodynamic conditions caused by the flow of liquid food, and biofilms grown under a wide distribution of hydrodynamic strengths. ObjetivesThe aim of the present work was to investigate the in situ thickness, architecture, and rheological properties of yeast biofilms growing on stainless steel under turbulent flow. Methods The yeast species used (Rhodototula mucilaginosa, Candida krusei, Candida kefyr and Candida tropicalis) were isolated from an apple juice industry. Biofilm formation in turbulent flow were performed in a Rotating Disk System (RDS) already described (Brugnoni et al., 2011). Viscoelastic properties of biofilms were determined by small deformation dynamic oscillatory measurements in a Paar Physica rheometer MCR301 (Anton Paar GmbH, Graz, Austria), using parallel plates.ConclusionsResults show yeasts biofilms formed on stainless steel at Reynolds (Re) numbers ranging from 294,000 to 1.2 × 106. These growth phases transform adherent blastospores to well-defined cellular communities. Biofilm formation increases with Re and time. Flow conditions impacted biofilm composition, with a predominance of C. krusei. Under turbulent flow in biofilm thickness increased >100 μm and cell morphology was governed by hyphal structures and rounded cells. Biofilms resulted viscoelastic materials with a solid-like behavior. Rheological values were not significantly affected by flow conditions or growth time. At large deformations their weak structure collapsed beyond a critical strain. Brugnoni LI, Cubitto MA, Lozano JE. 2011b. Role of shear stress on biofilm formation of Candida krusei in a Rotating Disk System. J. Food Process Eng. 102:266?271.