Navegando por Autor "Gelain, Lucas"

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    Continuous production of enzymes under carbon-limited conditions by Trichoderma harzianum P49P11
    (Elsevier) Gelain, Lucas; Kingma, Esther; Pradella, José Geraldo da Cruz; Costa, Aline Carvalho da; Wielen, Luuk Van Der; Gulik, Walter Martin van
    Carbon-limited chemostat cultures were performed using different carbon sources (glucose, 10 and 20 g/L; sucrose, 10 g/L; fructose/glucose, 5.26/5.26 g/L; carboxymethyl cellulose, 10 g/L; and carboxymethyl cellulose/glucose, 5/5 g/L) to verify the capability of the wild type strain Trichoderma harzianum to produce extracellular enzymes. All chemostat cultures were carried out at a fixed dilution rate of 0.05 h . Experiments using glucose, fructose/glucose and sucrose were performed in duplicate. Glucose condition was found to induce the production of enzymes that can catalyse the hydrolysis of p-nitro- phenyl-b-D-glucopyranoside (PNPGase). A concentration of 20 g/L of glucose in the feed provided the highest productivity (1048 ± 16 U/mol h). Extracellular polysaccharides were considered the source of inducers. Based on the obtained results, a new PNPGase production process was developed using mainly glucose. This process raises interesting possibilities of synthesizing the inducer substrate and the induced enzymes in a single step using an easily assimilated carbon source under carbon-limited conditions.
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    Replacement of the carbon catabolite regulator (cre1) and fed-batch cultivation as strategies to enhance cellulase production in Trichoderma harzianum
    (Elsevier) Delabona, Priscila da Silva; Lima, Deise Juliana; Codima, Carla Aloia; Ramoni, Jonas; Gelain, Lucas; Melo, Vandierly Sampaio de; Farinas, Cristiane Sanchez; Pradella, José Geraldo da Cruz; Seiboth, Bernhard
    This work focused on mitigating carbon catabolic repression (CCR) and increasing cellulase production in Trichoderma harzianum based on the cre1 deletion. The CRE1 protein (encoded by cre1) has been described as a cellulase transcriptional repressor in various cellulotic fungi, but has not been investigated in T. harzianum. We constructed ∆cre1 T. harzianum by replacing the cre1 gene with the amdS gene from Aspergillus nidulans. Quantitative PCR analysis of some Cazymes genes showed that CRE1 acts positively on gh61, bgl1 and xyn2. The fed-batch strategy using hydrothermal sugarcane bagasse by the ∆cre1_Th15 produced a constant rate of FPase under glucose influence, suggesting that the knockout of the carbon catabolite regulator improved the glycoside hydrolases (FPase 1.96 ± 0.32 IU/mL; β-glucosidase 5.67 ± 0.28 IU/mL and xylanase 327. 26 ± 14.25 IU/mL), so that this strain can be used for biorefinery purposes.