Characterization of dual-species biofilms formed by bacteria isolated from milk

This study evaluated biofilm formation of bacteria isolated from raw milk and investigated the composition of extracellular polymeric substances (EPS) using Raman spectroscopy. Biofilms were formed from six isolates on a 96 -well microplate at 7 and 25 degrees C in 1 and 10% reconstituted whole milk. Biofilms were then formed on stainless steel coupons at 7 degrees C from two isolates identified as strong biofilm producers. Pseudomonas fluorescens, a frequent contaminant of raw milk, forms single or dualspecies biofilms with Staphylococcus aureus; however, the sessile cell number of S. aureus remained constant over ten days. Raman spectroscopy identified that EPS composition varied with carbohydrate and protein substrates, the predominant components in P. fluorescens single or dual -species biofilms. Understanding the formation and composition of biofilms at different temperatures and in milk concentrations that simulate the equipment used in the dairy industry is a significant subsidy for establishing adequate sanitary protocols for their mitigation. (c) 2024 Elsevier Ltd. All rights reserved.