Rúbia Carvalho Gomes Corrêa

Endophytic fungi: expanding the arsenal of industrial enzyme producers

Endophytic fungi, mostly belonging to the Ascomycota, are found in the intercellular spaces of the aerial plant parts, particularly in leaf sheaths, sometimes even within the bark and root system without inducing any visual symptoms of their presence. These fungi appear to have a capacity to produce a wide range of enzymes and secondary metabolites exhibiting a variety of biological activities. However, they have been only barely exploited as sources of enzymes of industrial interest. This review emphasizes the suitability and possible advantages of including the endophytic fungi in the screening of new enzyme producing organisms as well as in studies aiming to optimize the production of enzymes through well-known culture processes. Apparently endophytic fungi possess the two types of extracellular enzymatic systems necessary to degrade the vegetal biomass: (1) the hydrolytic system responsible for polysaccharide degradation consisting mainly in xylanases and cellulases; and (2) the unique oxidative ligninolytic system, which degrades lignin and opens phenyl rings, comprises mainly laccases, ligninases and peroxidases. The obvious ability of endophytic fungi to degrade the complex structure of lignocellulose makes them useful in the exploration of the lignocellulosic biomass for the production of fuel ethanol and other value-added commodity chemicals. In addition to this, endophytic fungi may become new sources of industrially useful enzymes such as lipases, amylases and proteases.

Phytochemicals and bioactive properties of Ilex paraguariensis : An in-vitro comparative study between the whole plant, leaves and stems

The leaves, stems and whole plant of Ilex paraguariensis (yerba mate) were characterized in terms of their chemical composition and biological activities in order to determine which part of the plant is more interesting to develop bioactive formulations. The yerba mate samples contain at least five free sugars, five organic acids, eighteen fatty acids, one tocopherol, nine hydroxycinnamoyl derivatives and two flavonols. The leaf extract revealed the highest antioxidant activity, correlating with its highest levels of phenolic compounds. By contrast, the stem extract showed the highest anti-inflammatory potential and was also the most potent against MCF-7 and HepG2 cell lines, probably due to the presence of other phytochemicals. The absence of hepatotoxicity in the extracts was confirmed in porcine liver primary cells. Although the yerba mate extracts have been widely studied, this report shows for the first time the distinct potentialities of each individual part of the plant.

New phytochemicals as potential human anti-aging compounds: Reality, promise, and challenges

ABSTRACT Aging is an inevitable process influenced by genetic, lifestyle, and environmental factors. Indirect evidence shows that several phytochemicals can have anti-aging capabilities, although direct evidence in this field is still limited. This report aims to provide a critical review on aspects related to the use of novel phytochemicals as anti-aging agents, to discuss the obstacles found when performing most anti-aging study protocols in humans, and to analyze future perspectives. In addition to the extensively studied resveratrol, epicatechin, quercetin, and curcumin, new phytochemicals have been reported to act as anti-aging agents, such as the amino acid L-theanine isolated from green tea, and the lignans arctigenin and matairesinol isolated from Arctium lappa seeds. Furthermore, this review discusses the application of several new extracts rich in phytochemicals with potential use in anti-aging therapies. Finally, this review also discusses the most important biomarkers to test anti-aging interventions, the necessity of conducting epidemiological studies and the need of clinical trials with adequate study protocols for humans.

Analysis of a whole diet in terms of phenolic content and antioxidant capacity: effects of a simulated gastrointestinal digestion

Abstract This work compares the phenolic contents and the total antioxidant capacity of the 36 most popular Brazilian foods submitted to aqueous extraction or in vitro digestion. The purpose was to evaluate the extent by which digestion differs from the simple aqueous extraction procedures of several food matrices. After in vitro digestion, cereals, legumes, vegetables, tuberous vegetables, chocolates and fruits showed higher phenolic contents and higher antioxidant activities than those obtained by aqueous extraction. Contrarily, the digestion caused a reduction in the phenolic contents and antioxidant activities of beverages (red wine, coffee and yerba mate). Our results suggest that the phenolics of food groups with solid and complex matrix are protected against enzymatic action and alteration in pH during the digestion, what does not occur in liquid food matrices such as the beverages. This fact would overestimate the antioxidant activities of beverages submitted solely to aqueous extraction.

Antioxidant and rheological properties of guava jam with added concentrated grape juice

BACKGROUNDnGuava jam enriched by the addition of concentrated grape juice in the proportion of 30% (w/w) (ENR) was studied for its antioxidant potential and rheological behavior. Total phenolics content, 1,1-diphenyl-2-picrylhydrazyl radical (DPPH(•)) scavenging activity and β-carotene-linoleic acid coupled oxidation assays were used to evaluate the antioxidant properties of the samples during storage for 90 days at room temperature (25°C).nnnRESULTSnThe ENR showed a total phenolic content of 11.09 g GAE kg(-1) of jam at production, more than two-fold the phenolic content presented by the standard formulation (STA). For the ENR formulation the antioxidant capacity increased in almost 20% (P ≤ 0.05) with time on the β-carotene assay and decreased with time on the DPPH assay. The enriched guava jam exhibited a non-Newtonian shear-thinning behavior at temperatures ranging from 25 to 55°C, and, moreover, presented higher stability than the standard formulation when exposed to temperature variation.nnnCONCLUSIONnENR constitutes an original food product with a notable antioxidant potential, even greater than the potential presented by the standard guava jam, worldwide appreciated delicacy.

Spent mushroom substrate of Pleurotus pulmonarius: a source of easily hydrolyzable lignocellulose

Pleurotus pulmonarius was cultivated on a corncob-based substrate for producing of mushrooms and for assessing the transformation of the lignocellulosics during the development of fungal biomass. Associated events, such as the release of relevant enzymes and the H2O2 generation, were also monitored. The peaks of laccase and catalase activities occurred at the 5th day and that of Mn peroxidase at the 30th day, simultaneously with a high activity of superoxide dismutase. Increase in the endocellulase and xylanase activities was observed after 10xa0days, with maximal activities achieved during the 20–30-day period. Maximal values of H2O2 were found after 10xa0days of cultivation. Electron microscopy and Fourier transform infrared (FTIR) spectroscopy showed strong alterations in the lignocellulosic fibers. The uncultivated and the cultivated substrates at different times were hydrolyzed with commercial cellulase and β-glucosidase. The highest values of reducing sugars (110.5u2009±u20095.6xa0μmol/mL), being 65xa0% glucose, were obtained using the 20-day cultivated substrate. After the fruiting stage (first flush), enzymatic hydrolysis of the spent mushroom substrate (SMS) yielded 53.0u2009±u20092.8 and 77.5u2009±u20094.0xa0μmol/mL of glucose and total reducing sugars, respectively. Although the release of reducing sugars of the P. pulmonarius SMS was lower than that obtained after 20xa0days of cultivation, it was still 50xa0% higher than that obtained using the uncultured substrate. This observation, combined with the fact that SMS constitutes a residue generated as a by-product of the depletion of an agro-industrial residue, allows to conclude that this material offers an interesting economic perspective for the obtainment of cellulosic ethanol.

Enzymes from Basidiomycetes—Peculiar and Efficient Tools for Biotechnology

Abstract Basidiomycetes are considered to be a very interesting group of fungi given their exceptional adjustment abilities to accommodate themselves to the detrimental conditions of the environment where they constantly act as natural lignocellulose destroyers. Basidiomycetes possess the two types of extracellular enzymatic systems necessary to degrade the vegetal biomass: (1) a hydrolytic system responsible for polysaccharide degradation, consisting mainly of xylanases and cellulases and (2) a unique oxidative ligninolytic system, which degrades lignin and opens phenyl rings; this systemcomprises mainly laccases, ligninases, and peroxidases. Recent genomic studies of basidiomycetes have provided valuable information about the various ecological groups including white rot and brown rot fungi. The ability of basidiomycetes to degrade the complex structure of lignocellulose makes them potentially useful in the exploration of the lignocellulosic biomass for the production of fuel ethanol and other value-added commodity chemicals. No less important is their potential in biodegradation and bioremediation processes, thanks to the capability of their ligninolytic system in degrading a wide range of xenobiotic compounds. In this chapter, special attention is devoted to those enzymes typically produced by basidiomycetes with a high potential for biotechnological applications.

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.

Endophytes as Pollutant-Degrading Agents: Current Trends and Perspectives

Bioremediation is based on biological systems, bacteria, fungi, and plants. They are effective systems to treat a polluted site because they are able to modify the chemical structure of the contaminant into less hazardous end products. Investigations regarding the theme have immensely accelerated during the last years, what originated a great number of articles involving the terms “phytoremediation” and “bioremediation.” Initially the term phytoremediation was defined as being the use of plants for the degradation of polluting hazardous chemicals. However, the discovery that healthy plants could be containing endosymbiotic groups of microorganisms, often bacteria or fungi, led to the notion that these microorganisms could be, partly at least, responsible for the degradation of the pollutants. This review focuses on this proposed partnership in the bioremediation process, taking into account investigations conducted during the last 5 years.