The accumulation of exopolysaccharides (EPS) produced by microorganisms occurs in the presence of excess substrate and limiting conditions of elements that are essential to growth, such as nitrogen, phosphorus, sulfur, and magnesium. The presence of EPS produced by bacterial cells contributes to slime colonies formation in solid medium and increased viscosity in liquid medium. This paper proposes an alternative method for screening EPS-producing lactic acid bacteria using solid medium-containing discs of filter paper that are saturated with active cultures. The screening was carried out under different culture conditions varying the type of sugar, pH, and temperature. EPS production was visualized by the presence of mucoid colonies on the discs, which was confirmed by the formation of a precipitate when part of this colony was mixed with absolute alcohol. The established conditions for obtaining a high number of isolates producing EPS were 10% sucrose, pH 7.5 and 28 ºC. This method proved to be effective and economical because several strains could be tested on the same plate, with immediate confirmation.

The genus Leuconostoc belongs to a group of lactic acid bacteria usually isolated from fermented vegetables, which includes species involved in the production of exopolysaccharides (EPS). These biopolymers possess considerable commercial potential. Because of the wide variety of industrial applications of EPS, this study aimed to produce and characterize the native exopolysaccharide strain Leuconostoc pseudomesenteroides R2, which was isolated from cabbage collected in a semi-arid region of Bahia. We employed the following conditions for the production of EPS: 10.7% sucrose, pH 8.2, without agitation and incubation at 28°C for 30 hours. The fermentation broth was treated with ethanol and generated two types of polysaccharide substances (EPS I and EPS II). The identification of EPS I and EPS II was conducted using FT-IR, 1 H, 13 C and DEPT-135 NMR spectra. The two substances were identified as linear dextran α polysaccharides (1 → 6) which indicated different characteristics with respect to thermal analysis and density of free packaging, viscosity and time of solubilization. Both dextrans are of low density, possess high thermal stability and exhibited the behavior characteristic of pseudoplastic polymers.

ResumoA utilização de micro-organismos probióticos é uma das mais atrativas opções para consumo humano, devido às suas excelentes propriedades funcionais. Considerando-se que o desenvolvimento de novos produtos tem adquirido crescente importância, objetivou-se, neste trabalho, avaliar a aceitabilidade de barras de cereais com micro-organismos potencialmente probióticos. Utilizou-se a escala hedônica estruturada de nove pontos, que contém os termos descritivos situados entre "gostei extremamente" e "desgostei extremamente". Os atributos avaliados foram: aparência, textura, sabor e impressão global. Foi também realizada uma pesquisa de intenção de consumo, utilizando-se uma escala de cinco pontos situados entre "nunca comeria" e "comeria sempre". A avaliação sensorial foi realizada por uma equipe de 36 indivíduos não treinados: professores, estudantes e funcionários da Universidade Federal do Espírito Santo, de ambos os sexos, com idades entre 20 e 40 anos. As amostras foram apresentadas aos provadores em ordem aleatória, de forma monádica, devidamente identifi cadas com números de três dígitos. A utilização da levedura Saccharomyces boulardii e da bactéria Lactobacillus acidophilus, por meio das diferentes formas de incorporação nas barras de cereais, não interferiu na qualidade sensorial e estrutural do produto. As quatro formulações de barra de cereais apresentaram boa aceitação sensorial quanto a aparência, textura, sabor e impressão global. A pesquisa de intenção de consumo revelou que mais de 60% dos provadores consumiriam o produto sempre ou frequentemente. A viabilidade dos microorganismos por curto período de tempo torna necessária a realização de novos estudos, com o objetivo de aumentar a estabilidade destes micro-organismos durante a vida de prateleira do produto. Palavras-chave: Barra de cereais; Probióticos; Saccharomyces boulardii; Lactobacillus acidophilus. SummaryThe use of probiotic microorganisms is one of the most attractive options for human consumption due to their excellent functional properties. Considering that the development of new products has gained increasing importance, the aim of this work was to evaluate the acceptability of cereal bars with potentially probiotic microorganisms. A nine point structured hedonic scale was used containing the descriptive terms situated between "like extremely" and "dislike extremely". The attributes evaluated were aspect, texture, fl avour and overall impression. A survey of the intention to consume the product was also carried out using a fi ve point scale between "never consume" and "always consume". The sensory evaluation was carried out by a team of 36 untrained subjects: teachers, students and staff of the Federal University of Espírito Santo, of both sexes and aged between 20 and 40 years. The samples were presented to the panellists in random order in a monadic way, identifi ed with 3-digit numbers. The various ways of incorporating Saccharomyces boulardii and Lactobacillus acidophilus into the cereal bars did not affect the structural and sens...

The current study aims to assess the kinetics of population growth of Rhodotorula oryzicola and the production of β-1,3-glucanase (EC 3.2.1.39) enzyme by this yeast. It also aims to obtain the optimum conditions of β-1,3-glucanase enzymatic activity by varying the pH as well as to study the enzyme thermostability. R. oryzicola population doubled within 12 hr. During this period, 9.26 generations were obtained, with 1 hr and 29 min of interval from one generation to the other, with specific growth rate (µ) of 0.15 (hr). The entire microorganism growth process was monitored during β-1,3-glucanases production, and the maximum value was obtained in the stationary phase in the 48-hr fermentation period. pH and temperature optimum values were 4.7 and 96°C, respectively. The enzyme maintained 88% of its activity when submitted to the temperature of 90°C for an incubation period of 1 hr. The results show that the enzyme can be used in industrial processes that require high temperatures and acidic pH.

Probióticos são aditivos alimentares constituídos por microrganismos vivos que exercem efeitos benéficos no hospedeiro. Seu principal mecanismo de ação baseia-se no princípio da exclusão competitiva. Atualmente, diversos microrganismos vêm sendo isolados e selecionados para a formulação de produtos probióticos, que são classificados pela FDA (Food and Drug Administration) como um produto GRAS (Generally Recognized as Safe). Existem no mercado várias formulações probióticas, que podem ser constituídas por diferentes espécies de bactérias, fungos filamentosos e leveduras, ou por somente um tipo de microrganismo. As espécies de leveduras mais utilizadas correspondem a Saccharomyces cerevisiae e S. boulardii. A administração destas leveduras no hospedeiro foi relatada como segura e bem tolerada pelas crianças, porém recentemente alguns autores descreveram casos de septicemia e fungemia em pacientes imunossuprimidos e imunocompetentes recebendo bioterapia com estas leveduras. Assim, este trabalho consiste em uma revisão, onde são abordados os diferentes aspectos da relação dos microrganismos probióticos sobre a saúde humana e animal.