COMPARATIVE PROTEOMIC ANALYSIS PROVIDES INSIGHT INTO THE PROTEINS INVOLVED IN STAPHYLOCOCCUS AUREUS BIOFILM

Staphylococcus aureus (S.aureus) strains are highly adaptable and have the ability to form structures known as biofilms (Di Ciccio et al.,2015), leading to surface colonization and the creation of a niche where the bacteria appear more resistant to antimicrobials and disinfectants (Costerton et al., 1999; Fratamico et al., 2009). To date, studies on the use of proteomic techniques to understand the species-specific mechanisms of biofilm formation are still lacking. The goal of this study was to compare the proteomic profile of the sessile and planktonic form of different strains of S.aureus with different biofilm formation index. The experiment was conducted on six strains: S.a ATCC 35556 (strong biofilm producer), S.a ATCC 12600 (moderate biofilm producer), S.a ATCC 29213 (weak biofilm producer),and three S.a wild isolate (strong, moderate and weak biofilm producer). These isolates are well known for their ability to form stable biofilms. All this strains have been grown both in the planktonic and in the sessile form and analyzed through 2D electrophoresis coupled with MALDI-TOF MS. Differential protein expression of S. aureus has been evaluated among groups of sessile and planktonic forms in order to discover the mechanisms of biofilm formation common to all analyzed strains. Results highlighted the differential expression of more then 20 proteins. Among them, Putative universal stress protein (Q7A551), ATP-dependent 6-phosphofructokinase (A6U2G5), Putative antiporter subunit mnhE2 (Q2FJ11) and Phosphoribosylglycinamide formyltrasferase (Q5HH12). Obtained results suggest that there is a common mechanism of biofilm formation that needs further investigation. Understanding the common pathways involved in biofilm formation will help to the development of new methods to counteract biofilm formation and to improve food safety.