The production of xylitol from pentose-fermenting yeast is closely related to the amount of oxygen present in the culture medium. This study evaluated the effects of agitation and aeration in xylitol production using the yeast Starmerella meliponinorum FRP.09, previously isolated and selected due to its capacity to produce ethanol and xylitol from xylose. Fermentations were conducted in 125 mL flasks with 15 mL of culture medium and shaken at 150 rpm and 200 rpm without forced aeration and compared to fermentation in a static system. To assess the forced aeration, bioreactor was used with an air flow of 0.1 vvm and agitation of 100 rpm, 0.25 vvm / 150 rpm and 0.5 vvm / 200 rpm. Higher agitation and airflow significantly increased the xylose consumption. The yeast S. meliponinorum FRP.09 achieved the best xylitol yield of 0.6 g of xylitol per g of xylose consumed, when the fermentation was conducted with an air flow/rotation speed of 0.5 vvm / 200 rpm in bioreactor and 150 rpm in the fermentation flasks.

Cepas de Micrococcaceae são aplicadas em embutidos cárneos fermentados como culturas iniciadoras, onde vários membros desta família são naturalmente encontrados. O objetivo deste trabalho foi isolar e caracterizar Staphylococcus xylosus de embutidos cárneos artesanais produzidos na região Sul do Brasil. Dos 89 isolados que apresentaram atividades positiva para catalase e negativa para coagulase, 25 cepas foram selecionadas para caracterização fenotípica. Nove cepas identificadas como Staphylococcus xylosus por API-STAPH foram avaliadas para capacidade de redução de nitratos e o crescimento satidfatório das cepas foi verificado na presença de nitrito e NaCl, demonstrando seu potencial para utilização como culturas iniciadoras em embutidos cárneos fermentados. As cepas foram ainda avaliadas quanto ao gênero e espécie através da reação em cadeia da polimerase e apenas duas cepas foram identificadas como S. xylosus, diferindo dos resultados encontrados na caracterização fenotípica.

Micrococcaceae strains are applied to fermented sausage as starter cultures, where several members of this family are naturally found. The aim of the present work was to isolate and characterize Staphylococcus xylosus from artisanal sausages produced in South Region of Brazil. From 89 isolates presenting catalase positive and coagulase negative activities, 25 strains were selected for phenotypic characterization. Nine strains identified as Staphylococcus xylosus by API-STAPH were evaluated for their nitrate reduction capacity, which showed satisfactory growth of the strains in the presence of nitrite and sodium chloride, demonstrating their potential for use as starter cultures in fermented sausage. The strains were also evaluated through genus and species-specific PCR, which showed only two as S. xylosus, differing from results found in phenotypic characterization.

O objetivo do presente trabalho foi caracterizar cepas promissoras como cultivos iniciadores de Lactobacillus plantarum isoladas de embutidos cárneos fermentados naturalmente produzidos na região noroeste do Rio Grande do Sul, Brasil. Das 127 bactérias ácido láctica homofermentativas, Gram-positivo e catalase-negativo isoladas, dez foram aleatoriamente selecionadas e a caracterização fenotípica e a PCR espécie-específica foram realizadas. DNA genômico das cepas isoladas e das cepas de referência L. plantarum ATCC 8014 e L. pentosus ATCC 8041 foram amplificadas utilizando-se dois pares de iniciadores espécie-específicos para L. plantarum (16/Lpl e LbP11/LbP12). Os resultados da caracterização fenotípica e da PCR espécie-específica permitiram a identificação como Lactobacillus plantarum de cinco cepas das dez selecionadas.

The purpose of the present work was to characterize promising starter culture strains of Lactobacillus plantarum isolated from naturally fermented artisanal sausage manufactured in the northwestern region of Rio Grande do Sul state, Brazil. From 127 isolates of homofermentative, Gram-positive and catalase-negative lactic acid bacteria, ten isolates were randomly selected and the phenotypic characterization and species-specific PCR were performed. Genomic DNA from each isolated strain and from the reference strains L. plantarum ATCC 8014 and L. pentosus ATCC 8041 were amplified using two pairs of L. plantarum species-specific primers (16/Lpl and LbP11/LbP12). The results of the phenotypic characterization and species-specific PCR indicated that five out of ten isolates were Lactobacillus plantarum.