Biofilm formation on ultrafiltration membranes by yeast strains isolated from apple juice processing industries

Abstract

Four yeast strains (Candida tropicalis, C. krusei, C. kefyr and Rodhotorula mucilaginosa) isolated from an apple juice plant were evaluated for their ability to form monospecies biofilms on ultrafiltration membranes. Yeast attachment and biofilm formation was estimated at different contact times 2, 6, 24, 48, 72 h and one week using apple juice as food matrix and polyvinylidene fluoride membrane as contact surface. The highest counts recorded after one week trial were for C. tropicalis and C. krusei (9.02 ± 0.30 and 9.30 ± 0.29 log CFU cm-2 respectively), followed by C. kefyr (8.63 log CFU cm-2) and R. mucilaginosa with the lowest adhesion (7.68 log CFU cm-2). The present study supports the importance to examine the interactions among members of resident microbiota on surfaces commonly used for juice clarification processes and should alert about improving and adopting better cleaning and disinfection protocols as they can represent a serious hygienic-sanitary problem.