This work investigates the influence of the positive regulator XYR1 of Trichoderma harzianum on the production of cellulolytic enzymes, using sugarcane bagasse as carbon source. Constitutive expression of xyr1 was achieved under the control of the strong Trichoderma reesei pki1 promoter. Five clones with xyr1 overexpression achieved higher xyr1 expression and greater enzymatic productivity when cultivated under submerged fermentation, hence validating the genetic construction for T.
View Article and Find Full Text PDFBiomass is abundant, renewable and useful for biofuel production as well as chemical priming for plastics and composites. Deconstruction of biomass by enzymes is perceived as recalcitrant while an inclusive breakdown mechanism remains to be discovered. Fungi such as Myceliophthora thermophila M77 appear to decompose natural biomass sources quite well.
View Article and Find Full Text PDFThe use of glycerol obtained as an intermediate of the biodiesel manufacturing process as carbon source for microbial growth is a potential alternative strategy for the production of enzymes and other high-value bioproducts. This work evaluates the production of cellulase enzymes using glycerol for high cell density growth of Trichoderma harzianum followed by induction with a cellulosic material. Firstly, the influence of the carbon source used in the pre-culture step was investigated in terms of total protein secretion and fungal morphology.
View Article and Find Full Text PDFThe aim of this study was to develop a bioprocess for the production of β-glucosidase and pectinase from the fungus Annulohypoxylon stygium DR47. Media optimization and bioreactor cultivation using citrus bagasse and soybean bran were explored and revealed a maximum production of 6.26 U/mL of pectinase at pH 4.
View Article and Find Full Text PDFAccessory enzymes that assist biomass degradation could be used to improve the recovery of fermentable sugar for use in biorefineries. In this study, different fungal strains isolated from the Amazon rainforest were evaluated in terms of their ability to produce feruloyl esterase (FAE) and xylanase enzymes, and an assessment was made of the contributions of the enzymes in the hydrolysis of pretreated sugarcane bagasse. In the selection step, screening using plate assays was followed by shake flask submerged cultivations.
View Article and Find Full Text PDFBioresour Technol
March 2013
Supplementation of cellulase cocktails with accessory enzymes can contribute to a higher hydrolytic capacity in releasing fermentable sugars from plant biomass. This study investigated which enzymes were complementary to the enzyme set of Trichoderma harzianum in the degradation of sugarcane bagasse. Specific activities of T.
View Article and Find Full Text PDFBioresour Technol
March 2013
This work investigates the glycosyl hydrolase (GH) profile of a new Trichoderma harzianum strain cultivated under controlled bioreactor submerged fermentation. The influence of different medium components (delignified steam-exploded sugarcane bagasse, sucrose, and soybean flour) on GH biosynthesis was assessed using experimental mixture design (EMD). Additionally, the effect of increased component concentrations in culture media selected from the EMD was studied.
View Article and Find Full Text PDFThe objective of this work was to study the effect of early weaning on alimentary preference for the macronutrients protein, carbohydrate and fat in adult rats. Male Wistar rat pups were weaned by separation from the mother at 15 (D15) or 30 (D30) days old. Body weight and food intake were measured every 30 days until pups were 150 days old.
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