Influence of milk proteins on the adhesion and formation of Bacillus sporothermodurans biofilms: Implications for dairy industrial processing

Abstract Bacillus sporothermodurans is a producer of highly heat-resistant spores, which is a problem for the dairy industry worldwide. In this work, we studied the attachment and biofilm formation on stainless steel surfaces in contact with milk proteins (casein and whey). The results of the biofilm formation were obtained by the plate count method. In conjunction, biofilms (niches and cell sizes) were measured by scanning electron microscopy (SEM) on the 1st, 5th and 10th day. X-ray photoelectron spectroscopy (XPS) was a complementary technique that probed the conditioning of the substrate surface after 24 h. The milk proteins affected the total bacterial count in the samples, and also influenced the biofilm architecture. Sessile cell counts varied from 4.3 log CFU/cm2 in the attachment stage to up to 10.2 log CFU/cm2 in the matured biofilm stage. The spore counts varied from