Produção e caracterização bioquímica de uma fosfatase ácida de Trichoderma harzianum (ALL42)

• Autor(a) principal: SOUZA, Amanda Araujo
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tde/1267
• topic: Trichoderma harzianum; solubilização de fosfato; fosfatase ácida; Trichoderma harzianum, phosphate solubilization, acid phosphatase; CNPQ::CIENCIAS BIOLOGICAS::BIOQUIMICA::ENZIMOLOGIA

Trichoderma harzianum is a saprophytic fungus, known for its potential as a biological control agent of different phytopathogens that causes losses in crops. Its action is based on different mechanisms like volatile and non-volatile antibiotics production, competition for nutrient and space, production of hydrolytic enzymes and mycoparasitism. This fungus also plays an important role in the release of carbon, nitrogen and phosphorus from insoluble macromolecules to the medium, favoring the growth of plants. Phosphorus is a limiting nutrient for plant growth, however, over 80% of the phosphorus applied to the soil, it becomes unavailable, due to its adsorption, precipitation or conversion to organic form. One way to obtain phosphate compounds in soil is through the action of enzymes called phosphatases, which catalyze the hydrolysis of phosphate esters producing soluble phosphorus. High levels of acid phosphatase (ACP) were produced by Trichoderma harzianum ALL42. This study evaluated the ability of T. harzianumALL42produce acid phosphatases(ACPs) in minimal medium modified by varying the concentration of glucose and phosphate (KH2PO4). The results showed that the concentration of glucose and phosphate in the culture medium regulated the production of ACPs T. harzianum ALL42. Thisfungusproducedanacid phosphatase(ACPII) inculture mediumcontainingglucose0.5% and0.04% phosphate. Theenzymewaspartiallypurifiedby hydrophobic interaction chromatography on Phenyl Sepharose. A typical procedure provided 2,0 fold purification with 32.65 % yield. It was optimally active in the pH range 5,2 and at 50°C. The enzyme was heat-stable, retaining approximately 60% of its activity after heating for 60 min at 60°C. Kinetic parameters calculated for the hydrolysis of p-nitrophenyl phosphate by acid phosphatase were Km= 0,054 M and Vmax= 2,058 units.min-1. The enzyme was strongly inhibited by KH2PO4, FeCl3 and sodium tungstate. The enzyme is inhibited by KH2PO4 and sodium tungstate through mixed inhibition. The acid phosphatase hydrolyzed a number of phosphate esters ATP, ADP, AMP, D-glucose-1-phosphate, D-fructose-6-phosphate, includingphytic acid, showinganactivityofphytase.