Tatiane Brugnari

Proteases of Wood Rot Fungi with Emphasis on the Genus Pleurotus

Proteases are present in all living organisms and they play an important role in physiological conditions. Cell growth and death, blood clotting, and immune defense are all examples of the importance of proteases in maintaining homeostasis. There is growing interest in proteases due to their use for industrial purposes. The search for proteases with specific characteristics is designed to reduce production costs and to find suitable properties for certain industrial sectors, as well as good producing organisms. Ninety percent of commercialized proteases are obtained from microbial sources and proteases from macromycetes have recently gained prominence in the search for new enzymes with specific characteristics. The production of proteases from saprophytic basidiomycetes has led to the identification of various classes of proteases. The genus Pleurotus has been extensively studied because of its ligninolytic enzymes. The characteristics of this genus are easy cultivation techniques, high yield, low nutrient requirements, and excellent adaptation. There are few studies in the literature about proteases of Pleurotus spp. This review gathers together information about proteases, especially those derived from basidiomycetes, and aims at stimulating further research about fungal proteases because of their physiological importance and their application in various industries such as biotechnology and medicine.

Simultaneous Removal of the Antimicrobial Activity and Toxicity of Sulfamethoxazole and Trimethoprim by White Rot Fungi

The excessive use and ineffective treatments have turned antimicrobial drugs into common biologically active micropollutants which are contributing for the rising number of resistant bacteria. Considering the demand for alternative and efficient treatments for the removal of antibiotics from water matrices and also for treatment of expired drugs, the aim of this study was to evaluate the potential of Pleurotus ostreatus, Pleurotus pulmonarius, and Trametes sp. for degrading simultaneously trimethoprim (TMP) and sulfamethoxazole (SMX). Each strain was inoculated in a liquid medium composed of wheat bran extract, Vogel’s salts, and 50xa0mgxa0l−1 of each antibiotic. The production of laccase was stimulated by the presence of the drugs in cultures of all fungi evaluated. However, extracellular laccase activities were not statistically correlated (pxa0<xa00.05) to the reduction of TMP and SMX concentrations in liquid media. Biomass levels were also higher in the presence of the antibiotics. A significant (pxa0<xa00.05) correlation was observed between biomass production and SMX removal. Pleurotus spp. were more efficient than Trametes sp. in the removal of the drugs. Approximately 74% of SMX and 40% of TMP were removed from culture medium by P. ostreatus after 15xa0days of cultivation. The antibacterial and acute toxicity bioassays validated the effectiveness of the assessed fungi in degrading the drugs and hence inactivating its pharmacological activity.

Evaluation of diuron tolerance and biotransformation by the white-rot fungus Ganoderma lucidum

The white rot basidiomycete Ganoderma lucidum was evaluated for its capability to tolerate and to degrade the herbicide diuron. Diuron at a subtoxic concentration was added at the start of the cultivation in glucose liquid stationary cultures. Under this condition diuron was a laccase inducer. Almost 50% of the initially present diuron was removed after 15 d of cultivation. Two diuron metabolites were found N-(3,4-dichlorophenyl)-N-methylurea (DCPMU) and 3,4-dichlorophenylurea (DCPU). The addition of the cytochrome P450 inhibitors 1-aminobenzotriazole and piperonyl butoxide reduced significantly the capability of the fungus in degrading diuron. The activities of superoxide dismutase and catalase were significantly increased in the mycelial extracts by the presence of diuron. On the other hand, diuron did not cause any significant alteration in the levels of reactive oxygen species. Additionally, laccase could also degrade diuron in vitro and this degradation was increased by the addition of synthetic mediators, 3-ethylbenzthiazoline-6-sulphonic acid and acetylacetone. Significant reduction in the toxicity, as evaluated by the Lactuca sativa bioassay, was observed after G. lucidum treatment. In conclusion, G. lucidum is able to metabolize diuron by intra- and extracellular mechanisms, without the accumulation of toxic products.

A highly reusable MANAE-agarose-immobilized Pleurotus ostreatus laccase for degradation of bisphenol A

Bisphenol A (BPA) is an endocrine disruptor compound that is continuously released into the environment and is barely degraded in wastewater treatment plants. A previous study showed that free Pleurotus ostreatus laccase is efficient in degrading BPA producing less toxic metabolites. In the present study, this laccase was successfully immobilized onto MANAE-agarose, improving its efficiency in degrading BPA and its thermal and storage stabilities. In addition to this, the immobilized enzyme retained >90% of its initial capability to degrade BPA after 15cycles of reuse. P. ostreatus laccase immobilized onto MANAE-agarose could be an economical alternative for large scale degradation of BPA in aqueous systems.

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 180u202fkDa was produced in solid-state cultures using a mixture of pineapple crown leaves and wheat bran. Maximum production of the enzyme (820u202f±u202f30u202fU/g substrate) was obtained after 8u202fdays of culture at 28u202f°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.