This study was led with the purpose of evaluating the effectiveness of eugenol, beta-pinene and alpha-pinene in inhibiting the growth of potential infectious endocarditis causing gram-positive bacteria. The phytochemicals Minimum Inhibitory Concentration-MIC was determined by solid medium diffusion procedure, while the interference of the MIC values on the bacterial cell viability was performed by viable cells count. Staphylococcus aureus, S. epidermidis, Streptococcus pneumoniae and S. pyogenes strains were used as test microorganisms. The assayed phytochemicals showed effectiveness in inhibiting all assayed bacteria strains presenting MIC values between 2.5 and 40 µL/mL. Eugenol showed the lowest MIC values which were between 2.5 and 5 µL/mL for the most bacteria strains. MIC values found to the phytochemicals were able to inhibit the cell viability of S. aureus providing a total elimination of the bacteria inoculum in a maximum time of 24 hours of exposure. These data showed the interesting antibacterial property of the assayed phytochemicals and support their possible and rational use in the antimicrobial therapy. Este estudo foi conduzido com a proposta de avaliar a efetividade de eugenol, beta-pineno e alfa-pineno em inibir o crescimento de cepas de bactérias Gram-positivas potencialmente causadoras de endocardite infecciosa. A Concentração Inibitória Mínima-CIM dos fitoconstituintes foi determinada através do método de difusão em meio sólido, enquanto a interferência da CIM sobre a viabilidade celular bacteriana foi avaliada através da contagem de células viáveis. Cepas de Staphylococcus aureus, S. epidermidis, Streptococcus pneumoniae e S. pyogenes foram utilizadas como microrganismos teste nos ensaios antimicrobianos. Os fitoconstituintes ensaiados mostraram efetividade em inibir todas as cepas bacterianas utilizadas como microrganismos testes apresentando valores de CIM entre 2.5 e 40 µL/mL. Eugenol apresentou os menores valores de CIM, os quais estiveram entre 2,5 e 5 µL/mL para a maioria das cepas bacterianas. Os valores de CIM encontrados para os fitoconstituintes foram capazes de inibir a viabilidade celular de S. aureus causando uma total eliminação do inóculo bacteriano em um tempo máximo de 24 horas de exposição. Estes dados mostram o intenso potencial antibacteriano dos fitoconstituintes ensaiados e suportam sua possível e racional aplicação na terapia antimicrobiana

This study aimed to identify lactic acid bacteria (LAB) in byproducts of fruit (Malpighia glabra L., Mangifera indica L., Annona muricata L. and Fragaria vesca L.) pulp processing. Fifty strains of LAB were identified using matrix-assisted laser desorption/ionization–time of flight mass spectrometry (MALDI-TOF MS) and 16S rRNA gene sequence (16S rRNA) analysis. Species belonging to Lactobacillus genus were the predominant LAB in all fruit pulp processing byproducts. The average congruency between the MALDI-TOF MS and 16S rRNA in LAB species identification reached 86%. Isolates of L. plantarum, L. brevis, L. pentosus, L. lactis and L. mesenteroides were identified with 100% congruency. MALDI-TOF MS and 16S rRNA analysis presented 86% and 100% efficiency of LAB species identification, respectively. Further, five selected Lactobacillus strains (L. brevis 59, L. pentosus 129, L. paracasei 108, L. plantarum 49 and L. fermentum 111) were evaluated for desirable probiotic-related properties and growth behavior on two different cultivation media. The exposure to pH 2.0 sharply decreased the counts of the different Lactobacillus strains after a 1 or 2 h incubation, while varied decreases were noted after 3 h of exposure to pH 3.0. Overall, the exposure to pH 5.0 and to bile salts (0.15, 0.30 and 1.00%) did not decrease the counts of the Lactobacillus strains. All tested Lactobacillus strains presented inhibitory activity against Staphylococcus aureus, Salmonella Typhimurium, Salmonella Enteritidis, Listeria monocytogenes and Escherichia coli, and presented variable susceptibility to different antibiotics. The selected Lactobacillus strains presented satisfactory and reproducible growth behavior. In conclusion, MALDI-TOF MS and 16S rRNA analysis revealed high efficiency and congruency for LAB species identification, and the selected Lactobacillus strains may be candidates for further investigation of novel probiotic strains.