Antimicrobial activity of fixed oils found in Brazil nuts and sunflower seeds against microorganisms isolated from bovine subclinical mastitis

Concern with traces of antibiotics found in milk and resistant bacteria has led to the search for alternatives, mainly natural products, to treat mastitis. This study aimed at evaluating the antimicrobial activity of fixed oils found in Brazil nuts and sunflower seeds against microorganisms isolated from mastitic milk and at analyzing their fatty acids. The following microorganisms were isolated from milk produced by cows with subclinical mastitis and selected for the antimicrobial test: Staphylococcus aureus, Enterococcus spp., Candida spp. and Cryptococcus laurentii. The oil components and the antimicrobial activity were determined by gas chromatography and by the broth microdilution technique, respectively.  The following fatty acids were identified: myristic, palmitic, palmitoleic, margaric, stearic, oleic, linoleic, linolenic, arachidic, gadoleic, behenic and lignoceric. Averages of minimum inhibitory concentrations (MIC) for S. aureus, Enterococcus spp., Candida spp. and C. laurenti were 36.30; 21.35; 15.62 and 10.41 μg.mL-1 (Brazil nut oil) and 23.5; 19.21; 7.81 and 1.2 μg.mL-1 (sunflower seed oil), respectively. These values show that these oils, in low concentration, have antimicrobial activity against the microorganisms under study. Therefore, this study shows that these fixed oils may be used as therapeutic resources for the control of mastitis.    Key words: Mastitis, antimicrobial activity, fixed oils.