The fermentation efficiency exhibited by Saccharomyces cerevisiae on Sugarcane bagasse hydrolysate, by analyzing the effects of pre-treatment and detoxification / A eficiência da fermentação exibida por Saccharomyces cerevisiae no hidrolisado de bagaço de cana-de-açúcar, analisando os efeitos do pré-tratamento e destoxicação

In this study, the possibility of increasing fermentation efficiency of Saccharomyces cerevisiae on sugarcane bagasse (a type of lignocellulosic waste) was analyzed. Sugarcane bagasse was subjected to hydrothermal and acidic pre-treatment. Next, the enzymatic hydrolysis of raw biomass and each pre treated biomass was performed using CellicCtec® enzymatic complex to obtain sugarcane hydrolysate, hydrothermal hydrolysate and acidic hydrolysate. Next, these were fermented by S. cerevisiae to check if the by-products of enzymatic hydrolysis, furfural and acetic acid had an inhibitory effect on fermentation efficiency. Next, each pre-treated biomass was subjected to detoxification involving activated charcoal. Each detoxified biomass was tested for fermentation efficiency. The lignocellulosic composition for sugarcane hydrolysate, hydrothermal hydrolysate and acidic hydrolysate, varied significantly, and were found to be, for cellulose 36.7%, 27.7% and 63.7% respectively; for hemicellulose 22.2%, 4.4% and 12% respectively; and for lignin 21.2%, 27.7% and 28.7% respectively. The presence of furfural and acetic acid had a strong influence on the fermentation efficiency of S. cerevisiae, and affected the consumption of sugars in each biomass by more than 90%. Further, we found that the detoxification process increased fermentation efficiency by 12.7% for the hydrothermal hydrolysate while for the acidic hydrolysate no significant difference was observed. This study showed that fermentation with greater efficiency is viable through the combined use of hydrothermal pre-treatment and detoxification. This combination of methods also causes less pollution as compared with the method involving acid pre-treatment due to the reduced number of effluents produced.(AU)

Nesse trabalho avaliou-se a possibilidade de se aumentar a eficiência de fermentação de um hidrolisado de bagaço de cana submetido aos pré-tratamentos hidrotérmico (195 ºC, usando 200 rpm por 10 min) e ácido (0,5% (v/v) de ácido sulfúrico a 121ºC por 15 min) (carga de sólidos de 10% m/v). A hidrólise enzimática do material pré-tratado foi realizada utilizado o complexo enzimático CellicCtec® (60 FPU/gbiomassa seca, tampão citrato a 50 mM e pH 4,8) a 50ºC usando 150 rpm por 72h. Antes do processo de detoxificação, realizou-se um teste com a espécie de Saccharomyces cerevisiae para verificar se os compostos furfural (1 e 4g.L-1) e ácido acético (1 e 5% v/v) exerciam significativa inibição na espécie testada. O processo de detoxificação avaliou a concentração de carvão ativado (1, 3 e 5% m/v) e o tempo do processo (30, 45 e 60 min) a 30 ºC, 150 rpm por 24 h. A composição lignocelulosica da biomassa in natura e pré-tratada (hidrotérmico e ácido) foi para celulose (36,7, 27,7 e 63,7%), hemicelulose (22,2, 4,4 e 12%) e lignina (21,2, 27,7 e 28,7%), respectivamente e com rendimento mássico em torno de 60%. A presença de furfural e ácido acético exibiu forte influência na espécie considerada, chegando a prejudicar em mais de 90% o consumo de açúcares no meio. O processo de destoxificação aumentou 13% a eficiência de fermentação para o hidrolisado obtido hidrotermicamente, enquanto que para o ácido não houve diferença significativa. Obtendo assim uma fermentação com maior eficiência, tecnicamente viável e menos poluente.(AU)

Hepatite A: soroprevalência e fatores associados em escolares de São Luís (MA), Brasil / Hepatitis A: seroprevalence and associated factors among schoolchildren of São Luís (MA), Brazil

OBJETIVOS: Estimar a prevalência de anticorpos contra o vírus da hepatite A (antiVHA-IgG) em escolares de 7 a 14 anos de escolas públicas e privadas e identificar fatores demográficos, socioeconômicos e sanitários associados à prevalência de antiVHA-IgG. MÉTODOS: Estudo soroepidemiológico para detecção de antiVHA-IgG, de abril de 2002 a abril de 2004, em 462 escolares de São Luís, com idades compreendidas entre 7 e 14 anos, do ensino fundamental. Participaram 30 escolas aleatoriamente selecionadas, com probabilidade proporcional ao número de alunos matriculados, sendo 23 públicas e 7 privadas. Os dados foram obtidos por meio de questionário estruturado. Para se identificar variáveis independentemente associadas à prevalência do antiVHA-IgG, foi realizada análise de regressão de Poisson múltipla, sendo estimadas as RPs ajustadas e respectivos intervalos de confiança de 95 por cento. Somente permaneceram no modelo final aquelas variáveis associadas com a prevalência da hepatite A com p < 0,10. Foi adotado o nível de significância de 0,05 (α = 0,05). RESULTADOS: A prevalência de antiVHA-IgG foi de 64 por cento, sendo de 71,5 por cento nas escolas públicas e de 36,5 por cento nas privadas. Após análise multivariável, idade de 11 a 14 anos, mais de uma pessoa por dormitório e menos de dois banheiros por domicílio foi associada a maiores prevalências de antiVHA-IgG. Maior escolaridade dos pais esteve associada à menor prevalência de antiVHA-IgG. CONCLUSÕES: A hepatite A é endêmica nos escolares de São Luís, com taxa de prevalência semelhante àquela encontrada em outras regiões do país com condições socioeconômicas e sanitárias similares. Fatores historicamente associados à maior prevalência da hepatite A foram também identificados nesta população.

OBJECTIVES: To estimate the prevalence of antibodies to hepatitis A virus (antiVHA-IgG) in children aged 7-14 years from public and private schools, and to identify demographic, socioeconomic and sanitation factors associated with the prevalence of antiVHA-IgG. METHODS: Seroepidemiological study for the detection of IgG antiVHA. It was conducted from April 2002 to April 2004 with 462 elementary school students from São Luis, ranging from 7 to 14-years of age. Thirty schools randomly selected took part in the study, with a probability proportional to the number of students enrolled; 23 schools were public and 7 were private. Data was obtained through a structured questionnaire. In order to identify the variables independently associated with IgG antiVHA, the Poisson multiple regression analysis was performed, estimating the adjusted PRs and their 95 percent confidence intervals. The variables associated with the prevalence of hepatitis A with p < 0 were the only ones that remained in the final model. The level of significance of 0.05 (α = 0.05) was adopted. RESULTS: The prevalence of antiVHA-IgG was 64 percent, 71.5 percent in public and 36.5 percent in private schools. After multivariate analysis, age 11 to 14 years, more than one person per bedroom, and less than two bathrooms per household were associated with a higher prevalence of antiVHA-IgG. Higher parental education was associated with lower prevalence of antiVHA-IgG. CONCLUSIONS: Hepatitis A is endemic among schoolchildren in São Luís. The prevalence rate was similar to those found in other regions of the country with similar socio-economic and health conditions. Factors historically associated with a higher prevalence of hepatitis A were also identified in this population.

Hepatitis A: seroprevalence and associated factors among schoolchildren of São Luís (MA), Brazil.

OBJECTIVES: To estimate the prevalence of antibodies to hepatitis A virus (antiVHA-IgG) in children aged 7-14 years from public and private schools, and to identify demographic, socioeconomic and sanitation factors associated with the prevalence of antiVHA-IgG. METHODS: Seroepidemiological study for the detection of IgG antiVHA. It was conducted from April 2002 to April 2004 with 462 elementary school students from São Luis, ranging from 7 to 14-years of age. Thirty schools randomly selected took part in the study, with a probability proportional to the number of students enrolled; 23 schools were public and 7 were private. Data was obtained through a structured questionnaire. In order to identify the variables independently associated with IgG antiVHA, the Poisson multiple regression analysis was performed, estimating the adjusted PRs and their 95% confidence intervals. The variables associated with the prevalence of hepatitis A with p < 0 were the only ones that remained in the final model. The level of significance of 0.05 (α = 0.05) was adopted. RESULTS: The prevalence of antiVHA-IgG was 64%, 71.5% in public and 36.5% in private schools. After multivariate analysis, age 11 to 14 years, more than one person per bedroom, and less than two bathrooms per household were associated with a higher prevalence of antiVHA-IgG. Higher parental education was associated with lower prevalence of antiVHA-IgG. CONCLUSIONS: Hepatitis A is endemic among schoolchildren in São Luís. The prevalence rate was similar to those found in other regions of the country with similar socio-economic and health conditions. Factors historically associated with a higher prevalence of hepatitis A were also identified in this population.