Jorge Enrique Lozano
National University of Bahia Blanca, Argentina
Title: Yeast biofilm development and rheological properties development on turbulent flow regimes
Biography
Biography: Jorge Enrique Lozano
Abstract
In 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. Using industrially relevant strains of yeasts, it was demonstrated that 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 encased in an extracellular matrix and biofilm formation increases when increasing Re number and time. In situ rheological behavior of yeast biofilms growing on stainless steel under turbulent flow was also investigated. The species used (R. mucilaginosa, C. krusei, C. kefyr and C. tropicalis) were isolated from a clarified apple juice industry. The flow conditions impacted biofilm composition over time with a predominance of C. krusei under static and turbulent flow. Structural variations occurred with a tighter appearance under dynamic flow. Under turbulent flow there was an increase of 112 μm in biofilm thickness and cell morphology was governed by hyphal structures and rounded cells. Yeast biofilms were determined to be viscoelastic materials with a predominantly solid-like behavior and rheological values were not significantly affected by the flow conditions or the growth time. At large deformations their weak structure collapsed beyond a critical strain. The present work could represent a starting point for developing in situ measurements of yeast rheology and contribute to a thin body of knowledge about fungal biofilm formation.