Scanning electron microscopy of biofilm formation by Staphylococcus aureus on stainless steel and polypropylene surfaces

Attachment of bacteria to food processing equipment surfaces can lead to product contamination, spoilage, and surface destruction. Most of bacteria in their habitat live in communities of different degrees of complexity, in general composing biofilms. Once installed the biofilm, the resistance of these sessile organisms increases, making it difficult thus the action of sanitizers. This multidisciplinary study led to the description regarding the effect of antimicrobial solutions of essential oils of Syzygium aromaticum and Thymus vulgaris and their combination on biofilm formed by Staphylococcus aureus ATCC 25923 on AISI 304 stainless steel and polypropylene surfaces and evaluate the possible effects of these oils on Staphylococcus aureus cells after treatment with sanitizing solutions based on these natural compounds. All sanitizing solutions showed antibacterial potential, being effective in reducing bacterial biofilms on these surfaces. The solution containing the combination of essential oils was the most efficient by reducing 7.38 and 6.58 Log CFU.cm-2 of cells adhered on the surfaces of AISI 304 stainless steel and polypropylene, respectively, after 5 min of contact. Key words: Antimicrobial effect, microorganism, Syzygium aromaticum, Thymus vulgaris.