PRODUÇÃO DE XILANASE POR Aspergillus casielus COM DIFERENTES FONTES DE CARBONO

Neste trabalho foi avaliada a produção de xilanase por Aspergillus casielus, utilizando diversas fontes de carbono (resíduo ou bagaço de cevada, bagaço de cana, casca de amendoim, resíduo fibroso da mandioca, germe de trigo, bagaço de milho verde e casca de laranja). Dentre as fontes de carbono testadas na produção de xilanase pelo fungo A. casielus em condições de fermentação semi-sólida, os melhores indutores foram o bagaço de cevada seguido pela casca de amendoim com atividade especifica de 9,22 U/mg de proteína e 4,55 U/mg, respectivamente. Obeteve-se produção máxima de xilanase livre de celulase no 3º dia (72 horas) com atividade específica de 7,88 U/mg proteína. O pH ótimo e a temperatura ótima de atividade xilanásica foram 6,5 e 50ºC, respectivamente. A estabilidade térmica da xilanase na temperatura de 45ºC mostrouse praticamente constante, com perda de apenas 18% da atividade xilanolítica inicial em 90 minutos de reação. No entanto, nas temperaturas de 50ºC e 55ºC a enzima mostrou meia-vida de 50 e 17 minutos, respectivamente. Na análise dos produtos de hidrólise do xilano pela xilanase produzida por A. casielus verificou-se a formação de vários xilooligossacarídeos (xilose, xilobiose, xilotriose) indicando a ação de provável endoxilanase

Xylanase from Fusarium heterosporum: Properties and influence of thiol compounds on xylanase activity

The properties of xylanase purified from Fusarium heterosporum that was grown in barley-brewing residue under solid-state fermentation and the effects of thiol compounds on the reactivation of the metal ion-inhibited xylanase were investigated. Xylanase was purified to homogeneity by ion exchange chromatography, and its molecular mass was estimated to be 19.5 kDa by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH for the xylanase was 5.0, and it was stable in acidic pH (4.5 to 5.5), where it retained more than 87% of its activity after 24 h. The optimum temperature was 50°C, and it had a half-life of 53 min at 45°C. The apparent Km and Vmax values for the xylanase were 5.63 mg/ml and 800 μmol/mg/min, respectively. Ba2+, Ca2+, Mg2+ and the thiol compounds β-mercaptoethanol and dithiothreitol (DTT) enhanced xylanase activity, while Hg2+, Pb2+ and Zn2+ strongly inhibited enzyme activity. Furthermore, this xylanase had an alternative mode of regulation in the presence of thiol compounds because the enzyme was able to recover its catalytic activity after inhibition by heavy metal ions.Keywords: Hemicellulase, fungus, solid-state fermentation, barley brewing residue, thiol compoundsAfrican Journal of Biotechnology, Vol. 13(9), pp. 1047-1055, 26 February, 201

A thermostable xylanase from a new strain of Aspergillus fumigatus presents high ability to hydrolyze hemicellulose from corn straw / Uma xilanase termoestável de uma nova estirpe de Aspergillus fumigatus apresenta elevada capacidade de hidrolisar hemicelulose a partir de palha de milho

ABSTRACTIn order to optimize the production of xylanase from a new thermophilic strain of Aspergillus fumigatus (OI-1R-T), Plackett-Burman design (PBD) and central composite rotational design (CCRD) were performed. The response surface plots indicated a trend for increased xylanase biosynthesis with increasing concentrations of corn straw. The optimized xylanase activity was 530 U mL-1 in the presence of 6.5% (w/v) of the residual biomass, which was 11 times (1,157%) higher than that obtained with only the PBD (45.8 U mL-1). Interestingly, xylanase thermostability was maintained at 90% at 50 °C for 6 h. Enzymatic hydrolysis assays conducted for 96 h with 2 U mL-1 of xylanase and crude corn straw, pre-treated corn straw (hemicellulose) and xylan from beechwood, resulted in the net production of 3.89, 20.96 and 21.64 µmol mL-1of reducing sugars, respectively. Thus, A. fumigatus xylanase was equally able to hydrolyzes hemicellulose from corn straw and xylan from beechwood. The present data indicate that the xylanase activity of A. fumigatus could be applied to the production of low molecular weight sugars for use by pentose-fermenting yeast for the production of fuels and chemicals, among other products. 

Copper improves the production of laccase by the white-rot fungus Pleurotus pulmonarius in solid state fermentation

Pleurotus pulmonarius (Fr) Quélet, produced laccase as the main ligninolytic enzyme when cultivated on solid-state cultures using corn cob as substrate. The addition of copper greatly increased the production of enzyme. The addition of 25.0 mM CuSO4 increased the level of laccase from 270 to 1,420 U.L-1 and the fungus showed high resistance to copper under the conditions used in this work

Purification, biochemical characterization, and biotechnological applications of a multifunctional enzyme from the Thermoascus aurantiacus PI3S3 strain

Abstract The filamentous Thermoascus aurantiacus fungus characterized by its thermophilic nature, is recognized as an exceptional producer of various enzymes with biotechnological applications. This study aimed to explore biotechnological applications using polygalacturonase (PG) derived from the Thermoascus aurantiacus PI3S3 strain. PG production was achieved through submerged fermentation and subsequent purification via ion-exchange chromatography and gel filtration methods. The crude extract exhibited a diverse spectrum of enzymatic activities including amylase, cellulase, invertase, pectinase, and xylanase. Notably, it demonstrated the ability to hydrolyze sugarcane bagasse biomass, corn residue, and animal feed. The purified PG had a molecular mass of 36 kDa, with optimal activity observed at pH 4.5 and 70 °C. The activation energy (Ea) was calculated as 0.513 kJ mol−1, highlighting activation in the presence of Ca2+. Additionally, it displayed apparent K m, V max, and K cat values of at 0.19 mg mL−1, 273.10 U mL−1, and 168.52 s−1, respectively, for hydrolyzing polygalacturonic acid. This multifunctional PG exhibited activities such as denim biopolishing, apple juice clarification, and demonstrated both endo- and exo-polygalacturonase activities. Furthermore, it displayed versatility by hydrolyzing polygalacturonic acid, carboxymethylcellulose, and xylan. The T. aurantiacus PI3S3 multifunctional polygalacturonase showed heightened activity under acidic pH, elevated temperatures, and in the presence of calcium. Its multifunctional nature distinguished it from other PGs, significantly expanding its potential for diverse biotechnological applications