Differential role of gpaB and sidA gene expressions in relation to virulence in Aspergillus species from patients with invasive aspergillosis

Abstract The virulence genes in invasive aspergillosis (IA) have not been analyzed adequately. The present study was designed to evaluate the expression of gpaB and sidA genes, which are important virulence genes in Aspergillus spp. from bronchoalveolar lavage (BAL) samples. Direct examination and culture on Czapek Agar and Sabouraud Dextrose Agar media were performed for 600 BAL specimens isolated from patients with possible aspergillosis. A Galactomannan ELISA assay was also carried out. The expression levels of the gpaB and sidA genes in isolates were analyzed using quantitative real-time PCR (qRT-PCR). We identified 2 species, including Aspergillus flavus (A. flavus) and Aspergillus fumigatus (A. fumigatus) in 25 positive samples for invasive aspergillosis as validated using GM-ELISA. A. flavus is the main pathogen threatening transplant recipients and cancer patients worldwide. In this study, A. flavus had low levels of the gpaB gene expression compared to A. fumigatus (p = 0.006). The highest sidA expression was detected in transplant recipients (p = 0.05). There was no significant correlation between sidA expression and underlying disease (p = 0.15). The sidA and gpaB gene expression patterns may provide evidence that these virulence genes play important roles in the pathogenicity of Aspergillus isolates; however, there are several regulatory genes responsible for the unexpressed sidA and gpaB genes in the isolates.

Surface response methodology for the optimization of lipase production under submerged fermentation by filamentous fungi

Abstract A Plackett–Burman Factorial Design of 16 experiments was conducted to assess the influence of nine factors on the production of lipases by filamentous fungi. The factors investigated were bran type (used as the main carbon source), nitrogen source, nitrogen source concentration, inducer, inducer concentration, fungal strain (Aspergillus niger or Aspergillus flavus were selected as good lipase producers via submerged fermentation), pH and agitation. The concentration of the yeast extract and soybean oil and the pH had a significant effect (p < 0.05) on lipase production and were consecutively studied through a Full Factorial Design 23, with the concentration of yeast extract and pH being significant (p < 0.05). These variables were optimized using a central composite design, obtaining maximum lipolytic activities with the use of 45 g/L of yeast extract and pH 7.15. The statistical model showed a 94.12% correlation with the experimental data.

Biotransformation of sucrose into 5-hydroxy-2-hydroxymethyl-γ-pirone by Aspergillus flavus

The sucrose hydrolysis and the preference of consumption of glucose instead of fructose were investigated for the production of 5-hydroxy-2-hydroxymethyl-γ-pyrone (HHMP) in the presence of Aspergillus flavus IOC 3974 cultivated in liquid Czapeck medium. Standardized 0.5g of pellets were transferred as inoculum into twelve conical flasks of 250 ml containing 100 ml of medium with different sucrose concentration, which was kept at 120 rpm and 28"C for 16 days without pH adjustment. Aliquots of 500μl of the broth culture were withdrawn at 24 h intervals and analyzed. The major yield of HHMP was 26g l-1 in 120g l-1 of sucrose. At these conditions, A. flavus produced an invertase capable of hydrolyzing 65 percent of total sucrose concentration in 24h, and an isomerase capable of converting fructose into glucose. In this work, it focused the preference for glucose and, then, of fructose by A. flavus and the strategy used to produce HHMP.

Foram investigadas a hidrólise da sacarose e a preferência pela glicose frente à frutose no processo de produção do 5-hidroxi-2-hidroximetil-γ-pirona (HHMP) na presença de Aspergillus flavus IOC 3974 cultivado em meio líquido Czapeck. Quantidades de 0,5g de pelletes foram utilizadas como inóculo. Doze frascos cônicos de 250 ml contendo 100 ml de meio de culturacom diferentes concentrações de sacarose foram utilizados.Os microrganismos foram cultivados a 120 rpm e 28"C por 16 dias sem ajuste do pH. O maior rendimento do HHMP foi 26g l-1em 120g l-1de sacarose. Nestas condições, A. flavus, foi capaz de produzir uma invertase possibilitando a hidrólise de 65 por cento da concentração total de sacarose em 24 horas, conjuntamente com a produção de uma isomerase que foi capaz de converter a frutose em glicose. Este trabalho está focalizado preferencialmente no consumo da glicose frente à frutose por A. flavus e na estratégia de produção do HHMP.

Removal of gold, silver and copper by living and nonliving fungi from leach liquor obtained from the gold mining industry

Três linhagens de fungos, identificadas como Aspergillus flavus, Aspergillus fumigatus e Aspergillus niger, isoladas de amostras da planta de extraçäo de ouro da Mineraçäo Morro Velho (Nova Lima, Brasil), foram testadas quanto à capacidade de remover metais pesados em uma soluçäo obtida do circuito de beneficiamento de minério de ouro da mineraçäo (liquor de lixiviaçäo). Foi investida a habilidade desses fungos em remover ouro, prata e cobre via processos independentes do metabolismo (biomassa seca) e células cultivadas no liquor de lixiviaçäo. A biomassa seca das três linhagens estudadas apresentou uma baixa capacidade de bissorçäo de metais, provavelmente devido a elevada concentraçäo de cianeto no liquor de lixiviaçäo. Os fungos A. fumigatus e A. niger, quando metabolicamente ativos, apresentaram uma elevada habilidade de remoçäo desses metais. A presença de atividade metabólica nas células fúngicas

Control de alimentos y las aflatoxinas / Food control and aflatoxics

Entre los microorganismos que producen la contaminacion de los alimentos de consumo humano, se encuentra el Aspergillus flavus, a traves del factor toxico denominado Aflatoxina. las condiciones de temperatura de 20 a 38 grados centigrados los niveles de humedad de 14 a 30 por ciento , la presencia de nutrientes, ogigeno, etc, favorecen el desarrollo de estos hongos y la produccion de toxinas en los alimentos, producto de las inadecuadas condiciones higienico sanitarias. A todo esto se suman las dificultades economicas de los paises en desarrollo, donde existen problemas de desnutricion, patologias gastro-intestinales, enfermedades carenciales y un mayor consumo de hidratos de carbono, que proteinas, lo que incrementa la sensibilidad de la poblacion a las sustancias toxicas. El cancer hepatico es uno de los principales efectos patologicos relacionados con la aflatoxina, cuyo nivel de tolerancia en los productos alimenticios esta entre 3 a 25 mcg/Kg (5mcg/Kg para aflatoxina B1, que es la mas toxica). En Bolivia, INLASA acepta 10 mcg/Kg como nivel de tolerancia. La deteccion de aflatoxinas en el arroz vietnamita introducido al pais, debe ser el punto de partida para implementar un sistema de prevencion y control de alimentos contaminados, con la participacion de la poblacion y una coordinacion interinstitucional decidida