“…The increasing concern about resistant microorganisms stimulates the study of new and more effective antimicrobial agents (Raghunath and Perumal, 2017;Tang and Lv, 2014). New agents can be obtained from biological sources, such as bacteriocins and essential oils, or synthesized organic/inorganic compounds (Han, 2005;Medeiros et al, 2017;Medeiros et al, 2018). Good antimicrobial effects have been obtained from metal oxide nanoparticles (Raghunath and Perumal, 2017), such as MgO (Tang et al, 2012), Cu 2 O, CuO, ZnO, TiO 2 , and WO 3 (Duffy et al, 2018;Vargas-Reus et al, 2012), which present distinct behavior and properties from micrometric or millimetric particles (Azeredo, 2013;Martinez-Gutierrez et al, 2010;Morais and Durán, 2006).…”