Effect of soluble solids concentration on Neosartorya fischeri inactivation using UV-C light.

Ascospores of Neosartorya fischeri are heat-resistant and can survive thermal commercial treatments normally applied to the juices, as apple juice. Non-thermal processing of food such as exposure to ultraviolet light (UV-C) is reported to induce minimal quality changes while reduces microbial load. The main objective of this study was to determine the effect at different soluble solids concentration (12, 25, 30, 40, 50, 60 and 70 °Brix) on N. fischeri ascospores inactivation in apple juice, using UV-C light intensity (38 W/m2). Weibull model was fitted to experimental data. Then, a secondary model was used to describe how the inactivation kinetic parameters varied with the changes in soluble solids concentration. Results showed that the UV-C light had influence on N. fischeri ascospores inactivation in apple juice even at the highest soluble solids concentrations used, reaching approximately 4 log reductions at all concentrations used. The inactivation parameters, obtained by Weibull model, were δ (dose for the first decimal reduction) and p (the shape factor). Exponential model was chosen to describe the influence of soluble solids concentration on δ and p parameters. It can be concluded that UV-C light is a promising treatment with a drastic impact on the loads of N. fischeri, especially when low soluble solids concentration is used and a model was obtained to describe Brix effect.

Screening of thermotolerant and thermophilic fungi aiming Beta-xylosidase and arabinanase production

Plant cell wall is mainly composed by cellulose, hemicellulose and lignin. The heterogeneous structure and composition of the hemicellulose are key impediments to its depolymerization and subsequent use in fermentation processes. Thus, this study aimed to perform a screening of thermophilic and thermotolerant filamentous fungi collected from different regions of the São Paulo state, and analyze the production of β-xylosidase and arabinanase at different temperatures. These enzymes are important to cell wall degradation and synthesis of end products as xylose and arabinose, respectively, which are significant sugars to fermentation and ethanol production. A total of 12 fungal species were analyzed and 9 of them grew at 45 ºC, suggesting a thermophilic or thermotolerant character. Additionally Aspergillus thermomutatus anamorph of Neosartorya and A. parasiticus grew at 50 ºC. Aspergillus niger and Aspergillus thermomutatus were the filamentous fungi with the most expressive production of β-xylosidase and arabinanase, respectively. In general for most of the tested microorganisms, β-xylosidase and arabinanase activities from mycelial extract (intracellular form) were higher in cultures grown at high temperatures (35-40 ºC), while the correspondent extracellular activities were favorably secreted from cultures at 30 ºC. This study contributes to catalogue isolated fungi of the state of São Paulo, and these findings could be promising sources for thermophilic and thermotolerant microorganisms, which are industrially important due to their enzymes.

Screening of thermotolerant and thermophilic fungi aiming β-xylosidase and arabinanase production

Plant cell wall is mainly composed by cellulose, hemicellulose and lignin. The heterogeneous structure and composition of the hemicellulose are key impediments to its depolymerization and subsequent use in fermentation processes. Thus, this study aimed to perform a screening of thermophilic and thermotolerant filamentous fungi collected from different regions of the São Paulo state, and analyze the production of β-xylosidase and arabinanase at different temperatures. These enzymes are important to cell wall degradation and synthesis of end products as xylose and arabinose, respectively, which are significant sugars to fermentation and ethanol production. A total of 12 fungal species were analyzed and 9 of them grew at 45 ºC, suggesting a thermophilic or thermotolerant character. Additionally Aspergillus thermomutatus anamorph of Neosartorya and A. parasiticus grew at 50 ºC. Aspergillus niger and Aspergillus thermomutatus were the filamentous fungi with the most expressive production of β-xylosidase and arabinanase, respectively. In general for most of the tested microorganisms, β-xylosidase and arabinanase activities from mycelial extract (intracellular form) were higher in cultures grown at high temperatures (35-40 ºC), while the correspondent extracellular activities were favorably secreted from cultures at 30 ºC. This study contributes to catalogue isolated fungi of the state of São Paulo, and these findings could be promising sources for thermophilic and thermotolerant microorganisms, which are industrially important due to their enzymes.

Screening of thermotolerant and thermophilic fungi aiming ß-xylosidase and arabinanase production.

Plant cell wall is mainly composed by cellulose, hemicellulose and lignin. The heterogeneous structure and composition of the hemicellulose are key impediments to its depolymerization and subsequent use in fermentation processes. Thus, this study aimed to perform a screening of thermophilic and thermotolerant filamentous fungi collected from different regions of the São Paulo state, and analyze the production of ß-xylosidase and arabinanase at different temperatures. These enzymes are important to cell wall degradation and synthesis of end products as xylose and arabinose, respectively, which are significant sugars to fermentation and ethanol production. A total of 12 fungal species were analyzed and 9 of them grew at 45 °C, suggesting a thermophilic or thermotolerant character. Additionally Aspergillus thermomutatus anamorph of Neosartorya and A. parasiticus grew at 50 °C. Aspergillus niger and Aspergillus thermomutatus were the filamentous fungi with the most expressive production of ß-xylosidase and arabinanase, respectively. In general for most of the tested microorganisms, ß-xylosidase and arabinanase activities from mycelial extract (intracellular form) were higher in cultures grown at high temperatures (35-40 °C), while the correspondent extracellular activities were favorably secreted from cultures at 30 °C. This study contributes to catalogue isolated fungi of the state of São Paulo, and these findings could be promising sources for thermophilic and thermotolerant microorganisms, which are industrially important due to their enzymes.