Arely Prado-Barragán

Biotechnological Advances and Challenges of Tannase: An Overview

Tannase is one of the most versatile biocatalysts and plays an important role in a wide range of bioconversion reactions under protein-precipitating conditions. A comprehensive and illustrative review on the applied aspects of microbial tannases in modern biotechnological practices is presented. After a brief description of different substrates of tannases, fundamental biotechnological and catalytic aspects are reviewed and discussed to illustrate the pivotal role of tannases in the food and bioprocess industry. An emphasis on the biotechnological advances and challenges of tannase study is made.

The complete biodegradation pathway of ellagitannins by Aspergillus niger in solid‐state fermentation

Our research group has found preliminary evidences of the fungal biodegradation pathway of ellagitannins, revealing first the existence of an enzyme responsible for ellagitannins degradation, which hydrolyzes pomegranate ellagitannins and it was called ellagitannase or elagitannin acyl hydrolase. However, it is necessary to generate new and clear information in order to understand the ellagitannin degradation mechanisms. This work describes the distinctive and unique features of ellagitannin metabolism in fungi. In this study, hydrolysis of pomegranate ellagitannins by Aspergillus niger GH1 was studied by solid‐state culture using polyurethane foam as support and pomegranate ellagitannins as substrate. The experiment was performed during 36 h. Results showed that ellagitannin biodegradation started after 6 h of fermentation, reaching the maximal biodegradation value at 18 h. It was observed that ellagitannase activity appeared after 6 h of culture, then, the enzymatic activity was maintained up to 24 h of culture reaching 390.15 U/L, after this period the enzymatic activity decreased. Electrophoretic band for ellagitannase was observed at 18 h. A band obtained using non‐denaturing electrophoresis was identified as ellagitannase, then, a tandem analysis to reveal the ellagitannase activity was performed using Petri plate with pomegranate ellagitannins. The extracts were analyzed by HPLC/MS to evaluate ellagitannins degradation. Punicalin, gallagic acid, and ellagic acid were obtained from punicalagin. HPLC/MS analysis identified the gallagic acid as an intermediate molecule and immediate precursor of ellagic acid. The potential application of catabolic metabolism of ellagitannin hydrolysis for ellagic acid production is outlined.

Optimization of Ellagitannase Production by Aspergillus niger GH1 by Solid-State Fermentation

Ellagic acid is one of the most bioactive antioxidants with important applications in pharmaceutical, cosmetic, and food industries. However, there are few biotechnological processes developed for its production, because it requires precursors (ellagitannins) and the corresponding biocatalyst (ellagitannase). The aim of this study was to optimize the culture conditions for ellagitannase production by Aspergillus niger in solid-state fermentation (SSF). The bioprocess was carried out into a column bioreactor packed with polyurethane foam impregnated with an ellagitannins solution as carbon source. Four strains of Aspergillus niger (PSH, GH1, HT4, and HC2) were evaluated for ellagitannase production. The study was performed in two experimental steps. A Plackett–Burman design was used to determine the influencing parameters on ellagitannase production. Ellagitannins concentration, KCl, and MgSO4 were determined to be the most significant parameters. Box–Behnken design was used to define the interaction of the selected parameters. The highest enzyme value was obtained by A. niger PSH at concentrations of 7.5 g/L ellagitannins, 3.04 g/L KCl, and 0.76 g/L MgSO4. The methodology followed here allowed increasing the ellagitannase activity 10 times over other researcher results (938.8 U/g ellagitannins). These results are significantly higher than those reported previously and represent an important contribution for the establishment of a new bioprocess for ellagic acid and ellagitannase production.

Whole Cell Bioconversion of (+)-valencene to (+)-nootkatone in 100 % Organic Phase using Yarrowia lipolytica 2.2ab

Abstract The aim of this work was to assess the whole cell bioconversion of (+)-valencene to (+)-nootkatone in 100 % organic phase (orange essential oil) using a stirred tank bioreactor. Yarrowia lipolytica 2.2ab was used to perform bioconversion experiments; 600 mL of orange essential oil was inoculated with 50 cm3 of cell paste containing 13.5 g of biomass previously permeabilized with 0.2 % (w/v) of cetyl trimethylammonium bromide (CTAB) and enriched with 2.0 mM niacin. Experiments were conducted at 200 rpm, 0.5 vvm and 30 °C. The highest (+)-nootkatone yield was ca. 773 mg L−1 after 4 days of conversion. Bioconversion percent and volumetric productivity increased to 82.3 % and 8.06 mg L−1 h−1 compared to those reported previously using a three-phase partitioning bioreactor. The absence of free water in the system did not affect the performance of Y. lipolytica 2.2ab.

Incremento de la capacidad antioxidante de extractos de pulpa de café por fermentación láctica en medio sólido

La pulpa de café es una excelente fuente de antioxidantes naturales, la mayoría de los cuales son difíciles de eliminar, debido a su interacción química en las paredes celulares. Estos compuestos bioactivos pueden ser obtenidos por el proceso de extracción asistida por fermentación (FAE). En este estudio, las propiedades antioxidantes de extractos de pulpa de café fueron evaluadas por los ensayos de barrido de radicales ABTS y DPPH después de que este residuo fue pretratado por FAE usando diversas bacterias en un bioproceso de fermentación láctica en estado sólido. Los compuestos bioactivos liberados fueron identificados usando HPLC-MS. Lactobacillus casei mejoró la capacidad antioxidante de los extractos debido a la liberación de altas concentraciones de compuestos fenólicos como ácido clorogénico y resorcinol.

Utilization of Citrus Waste Biomass for Antioxidant Production by Solid-State Fermentation

Citrus fruits such as lemon, orange, grapefruit, and tangerine are consumed for their flavor, low cost, and human health benefits. However, citrus juice extraction generates by-products that are mostly unused and is discharged in landfills. In this study, the by-products of lemon, orange, grapefruit, and tangerine were subjected to solid-state fermentation (SSF) using Fusarium oxysporum, Penicillium purpurogenum GH2, Trichoderma harzianum T1-04, and Aspergillus niger GH1 to enhance their antioxidant activity. After fermentation, ethanol extracts were obtained and tested for their antioxidative activity by employing three techniques, 2,2-diphenyl-1-picrylhydrazyl (DPPH˙), ferric reducing antioxidant power (FRAP), and lipid oxidation inhibition (LOI). An increase in antioxidant activity from 33.13 to 41.62 mg/gmsi of antioxidants after fermentation of tangerine by-products by A. niger GH1 was observed. Major compounds present in ethanol extracts obtained after fermentation by A. niger GH1were identified by HPLC-MS, and their m/z corresponded to chlorogenic acid, didymin, naringin, and hesperidin. These results indicated that SSF is a suitable method to enhance antioxidant activity of citrus by-products.