Interference of sodium alginate and 2,2’-bipyridyl on bacterial growth and biofilm produced by Staphylococcus aureus isolates from bovine mastitis

S. aureus is considered the main etiologic agent of mastitis, standing out for its ability to produce biofilm, a structure of resistance against antibiotics and the host's immune system. Iron is an essential micronutrient in different biochemical pathways, being associated with the regulation of gene expression and biofilm production. In turn, iron chelators prevent the use of this nutrient by microorganisms, impairing growth. Therefore, the objective of this study was to evaluate the interference of iron chelators (sodium alginate and 2,2'-bipyridyl) on bacterial growth and on the biofilm produced by S. aureus from bovine mastitis. For this purpose, methodologies were developed based on the evaluation of the antimicrobial activity of the compounds, as well as the analysis of the interference with biofilm formation and bacterial growth under different conditions. In addition, an analysis of presence of resistance genes and the icaA, icaD, sbnD and sfaD genes was performed. Although 100% of them had important genes associated with the production of siderophores (sbnD and sfaD), the two chelators were able to interfere with the growth of the isolates. The isolates produced biofilm and had the icaA and icaD genes. Although there was no significant interference with biofilm formation, the two chelators interfered with mature biofilm. 2,2'-bipyridyl, in particular, harms the biofilm formed in 66.66% of isolates. Although the results showed strain-dependent performance, the study showed the potential of sodium alginate and 2,2'-bipyridyl in combating biofilm produced by S. aureus, which is promising in the treatment of mastitis.