Roselene Ferreira Oliveira

Degradation of Diuron by Phanerochaete chrysosporium: Role of Ligninolytic Enzymes and Cytochrome P450

The white-rot fungus Phanerochaete chrysosporium was investigated for its capacity to degrade the herbicide diuron in liquid stationary cultures. The presence of diuron increased the production of lignin peroxidase in relation to control cultures but only barely affected the production of manganese peroxidase. The herbicide at the concentration of 7 μg/mL did not cause any reduction in the biomass production and it was almost completely removed after 10 days. Concomitantly with the removal of diuron, two metabolites, DCPMU [1-(3,4-dichlorophenyl)-3-methylurea] and DCPU [(3,4-dichlorophenyl)urea], were detected in the culture medium at the concentrations of 0.74 μg/mL and 0.06 μg/mL, respectively. Crude extracellular ligninolytic enzymes were not efficient in the in vitro degradation of diuron. In addition, 1-aminobenzotriazole (ABT), a cytochrome P450 inhibitor, significantly inhibited both diuron degradation and metabolites production. Significant reduction in the toxicity evaluated by the Lactuca sativa L. bioassay was observed in the cultures after 10 days of cultivation. In conclusion, P. chrysosporium can efficiently metabolize diuron without the accumulation of toxic products.

Inhibition of Pancreatic Lipase and Triacylglycerol Intestinal Absorption by a Pinhão Coat (Araucaria angustifolia) Extract Rich in Condensed Tannin

The purpose of the present work was to characterize the possible inhibition of pancreatic lipase by a tannin-rich extract obtained from the pinhão (Araucaria angustifolia seed) coat, based on the previous observation that this preparation inhibits α-amylases. Kinetic measurements of pancreatic lipase revealed that the pinhão coat tannin is an effective inhibitor. Inhibition was of the parabolic non-competitive type. The inhibition constants, K¯i1 and K¯i2, were equal to 332.7 ± 146.1 μg/mL and 321.2 ± 93.0 μg/mL, respectively, corresponding roughly to the inhibitor concentration producing 50% inhibition ([I]50). Consistently, the pinhão coat extract was also effective at diminishing the plasma triglyceride levels in mice after an olive oil load; 50% diminution of the area under the plasma concentration versus the time curve occurred at a dose of 250 mg/kg. This observation is most probably the consequence of an indirect inhibition of triglyceride absorption via inhibition of pancreatic lipase. For the pinhão coat tannin, this is the second report of a biological activity, the first one being a similar inhibition of the absorption of glucose derived from starch as a consequence of an inhibitory action on α-amylases. Taken together, these effects represent a potential anti-obesity action, as suggested for other polyphenol or tannin-rich preparations.

Production of tannase and gallic acid by Aspergillus tamarii in submerged and solid state cultures

The hydrolytic enzyme, tannase and the antioxidant phenolic compound, gallic acid are useful in many biotechnological processes especially in food and pharmaceutical areas. The purpose of this study was to evaluate the production of tannase and gallic acid by Aspergillus tamarii developed in submerged and solid state cultures using tannic acid as substrate. In submerged cultures, maximal tannase activity (20,400 ± 2,900 U/L) was obtained after 2 days of cultivation using 2% tannic acid as substrate. In solid state cultivation using polyurethane foam as inert support, maximal tannase activity was obtained after 4 days of cultivation in 15% tannic acid cultures (25,470 ± 1,600 U/L). In both types of cultures, high accumulation of gallic acid was found in the two day-culture filtrates, 0.36±0.05 and 0.67±0.08 g of gallic acid per g of tannic acid, in submerged and solid state cultures, respectively. The accumulation of gallic acid in the cultures is, however, a transitory phenomenon, considering that the fungus slowly absorbs and metabolizes gallic acid. Key words: Aspergillus tamari, gallic acid, inert support, solid-state cultures, submerged cultures, tannase.

Immobilization of Aspergillus awamori β-glucosidase on commercial gelatin: An inexpensive and efficient process

In this work, a β-glucosidase of Aspergillus awamori with a molecular weight of 180 kDa was produced in solid-state cultures using a mixture of pineapple crown leaves and wheat bran. Maximum production of the enzyme (820 ± 30 U/g substrate) was obtained after 8 days of culture at 28 °C and initial moisture of 80%. The crude enzyme was efficiently immobilized on glutaraldehyde cross-linked commercial gelatin. Immobilization changed the kinetics of the enzyme, whose behavior could no longer be described by a saturation function of the Michaelis-Menten type. Comparative evaluation of the free and immobilized enzyme showed that the immobilized enzyme was more thermostable and less inhibited by glucose than the free form. In consequence of these properties, the immobilized enzyme was able to hydrolyze cellobiose more extensively. In association with Trichoderma reesei cellulase, the free and immobilized β-glucosidase increased the liberation of glucose from cellulose 3- and 5-fold, respectively. Immobilization of the A. awamori β-glucosidase on glutaraldehyde cross-linked commercial gelatin is an efficient and cheap method allowing the reuse of the enzyme by at least 10 times.

Inibição da Lipase Pancreática e da Absorção Intestinal de Triacilglicerídeos pelo Extrato de Casca de Pinhão (Araucaria angustifolia)

Instituto Federal de Mato Grosso do Sul – Coordenação de Alimentos, CEP 79400000, Coxim, MS, BrasilE-mail: (roselene.oliveira@ifms.edu.br) Universidade Estadual de Maringá– Departamento de Bioquímica CEP 87020900, Maringá, PR, Brasil Universidade Federal da Fronteira Sul – Departamento de Nutrição CEP 89802-265 Realeza, PR, Brasil Instituto Federal do Paraná – Coordenação de Alimentos CEP 86400000, Jacarezinho, PR, Brasil