Solid bioprocess of tarbush (Flourensia cernua) leaves for ß-glucosidase production by Aspergillus niger: initial approach to fiber-glycoside interaction for enzyme induction.

Commercial cellulase production has increased in recent years and consistent research has been carried out to improve levels of ß-glucosidase. Bioprocesses have been successfully adapted to produce this enzyme, with solid-state fermentations as the best-suited technique involving fungi. The aim of this study was to use leaves of tarbush (Flourensia cernua), an abundant shrub of the Chihuahuan Desert, as a carbon source for ß-glucosidase production by Aspergillus niger. During the solid bioprocess, this enzyme reached its peak production at 36 h of culture with 3876.6 U/L. There is a particular interest in the substrate composition because of the possibility of phenolic glycosides having an important role in ß-glucosidase production. HPLC-MS analyses showed that glycosides were present with the highest accumulation at 36 h of fungal culture. Luteolin and apigenin glycosides [1.8 and 2.4 absorbance units, respectively] were also detected and showed their highest point of detection alongside the highest ß-glucosidase activity. No apparent changes in cellulose were observed, while hemicellulose content decreased, which could be related to production and activity of ß-glucosidase. This study shows that leaves of F. cernua are an important raw material for ß-glucosidase production and give a source of compounds of added value which also may have an important role for ß-glucosidase production.

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.

Antifungal ellagitannin isolated from Euphorbia antisyphilitica Zucc.

OBJECTIVE: To study antifungal activity of a new ellagitannin isolated from the plant residues of Euphorbia antisyphilitica (E. antisyphilitica) Zucc in the wax extraction process. METHODS: An extract was prepared from dehydrated and pulverized residues and fractionated by liquid chromatography on Amberilte XAD-16, until obtained an ellagitannin-rich ethanolic fraction which was treated by rotaevaporation to recover the ellagitannin as fine powder. An aqueous solution was prepared and treated through ionic exchange liquid chromatography (Q XL) and gel permeation chromatography (G 25). The ellagitannin-rich fraction was thermogravimetrically evaluated (TGA and DTA) to test the thermo-stability of ellagic acid (monomeric unit). Then ellagitannin powder was analyzed by infrared spectrospcopy to determinate the functional groups and, also mass spectroscopy was used to determine the molecular ion. RESULTS: The principal functional groups of ellagitannin were determined, the molecular weight was 860.7 g/mol; and an effective antifungal activity against phytopathogenic fungi was demonstrated. CONCLUSIONS: It can be concluded that the new ellagitannin (860.7 g/mol) isolated from E. antisyphilitica Zucc is an effective antifungal agent against Alternaria alternata, Fusarium oxyzporum, Colletotrichum gloeosporoides and Rhizoctnia solani.