Microbacterium: adapted bacteria to microfiltrated milk

Microfiltration is a widespread technology applied to reduce the bacterial content during milk treatment. It is usually associated to pasteurization to further extend the shelf life of milk. The aim of this work was to evaluate the presence of bacteria in microfiltrated milk from the production process to the end of the shelf life. MATERIAL AND METHODS Milk samples were collected in two different plants located in Italy. Multiple time points were considered during the milk processing of the first plant, along with three different seasons. Samples from the second plant s were collected from freshly packaged at different time points. Additional samples were provided at the retail store. The following analyses were carried out for each sample: Total Bacterial Count (TBC), Bacillus cereus, Enterobacteriaceae (using enrichment medium). The colonies (about 10% of the plate) were randomly selected from the plates, purified by streaking on MPCA and then isolates were identified using the 16S rRNA gene Sanger sequencing. The proteolytic and lipolytic activity of Microbacterium isolates were evaluated using spotting technique on milk and tributyrin agar plates . Biofilm production was evaluated by streaking the strains isolated on Congo Red Agar (CRA) medium. The antibiotic resistance profile was determined according to CLSI standard methods. Moreover, bacterial growth capability in milk was also assessed at 8°C.