Stevia Rebaudiana fraction presents broad-spectrum antibacterial action and antibiofilm action for Staphylococcus aureus / Fração Stevia Rebaudiana apresenta ação antibacteriana de amplo espectro e ação antibiótica para Staphylococcus aureus

Fractions of S. rebaudiana leaves, extracted in Ethyl Acetate (EAF), rich in antioxidant compounds and Isobutanolic fraction (IF), with a high content of glycosides, were evaluated for antibacterial and antibiofilm potential against reference strains of Gram-positive and Gram-negative bacteria of clinical interest. EAF had bactericidal action against Gram-positive strains evaluated and against most Gram-negative strains, with the exception of Salmonella enteritidis. Gram-positive species showed greater sensitivity to EAF. For IF, up to the maximum concentration, there was no bactericidal effect for the strains. The pretreatment of planktonic cells of S. aureus with subinhibitory concentrations of EAF determined a reduction in the potential of structuring of the biofilm by up to 71%. The fraction showed effectiveness in biofilm treatments formed by S. aureus, with a 99% reduction in cell viability compared to the control. In addition to the antibacterial action on planktonic cells, EAF has promising effects against S. aureus biofilms

Growth of Fungal Cells and the Production of Mycotoxins

Some filamentous fungi are able to grow in food and produce toxic metabolites. It occurs mainly in grains, cereals, oilseeds and some by-products. The growth of fungi in a particular food is governed largely by a series of physical and chemical parameters. The production of toxic metabolites is not confined to a single group of molds irrespective of whether they are grouped according to structure, ecology, or phylogenetic relationships. Mycotoxins can be carcinogenic and cause several harmful effects to both human and animal organisms, in addition to generating large economic losses. The major mycotoxins found in food are the aflatoxins, fumonisins, ochratoxins, patulin, zearalenone, and trichothecenes, generally stable at high temperatures and long storage periods. Considering the difficult prevention and control, international organizations for food safety establish safe levels of these toxins in food destined for both human and animal consumption. Good agricultural practices and control of temperature and moisture during storage are factors which contribute significantly to inhibit the production of mycotoxins. The use of some fungistatic products, such as essential oils and antioxidants, as well as physical, mechanical, chemical, or thermal processing, represents important methods to have the concentration of mycotoxins reduced in food