99A-13 |
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J. M. LOEZA-CORTE1, J. R. Verde-Calvo1, F. Cruz-Sosa1, E. J. Vernon-Carter2, and S. Huerta-Ochoa1. (1) Biotechnology, Universidad Autónoma Metropolitana Iztapalapa, San Rafael Atlixco No. 186, Col. Vicentina, Mexico City, 09340, Mexico, (2) IPH, Universidad Autónoma Metropolitana Iztapalapa, San Rafael Atlixco No. 186, Col. Vicentina, Mexico City, 09340, Mexico L-arabinose is a compound of major economic interest due to its use as food additive. It is distributed in the form of complex polysaccharides (arabinoxylanes, arabinogalactans, arabinopyranoses) in biopolymers, and can be obtained by acid or enzymatic hydrolysis, the latter offering advantages over the former such as high specificity over substrate, stable reaction conditions, and mild and environmentally friendly processing conditions. The enzymatic hydrolysis of cellulose materials for producing fermentable sugars for industrial usage has acquired importance in the production of foods and energy. The objective of this work was to obtain an enzymatic extract from Aspergillus niger 10 that hydrolyzes the bond 1-5 in biopolymers containing residues of L-arabinose. The fungus was inoculated in a minimum medium composed by 10 g of mesquite gum as the carbon source, 2.54 g NaNO3, 1.5 g KH2PO4, 0.5 g KCl and 0.5 g MgSO4∙7H2O in 1 L water. Initial pH was adjusted to 5.5. Inoculates were maintained at 30°C during 96 h. The a-L-Arabinofuranoside activity was determined in 0.15 mL of the extract with 0.15 mL of a solution 4mM of p-Nitrophenyl-a-L-arabinofuranoside in citrate-phosphate buffer (pH 5.5) during 10 min at 40°C. The liberation of p-nitrophenol was determined by the addition of 0.9 mL of Na2CO3 0.1 M and the absorbance was measured at 400 nm. Experimental data indicate that fermentation time affects significantly the enzymatic extract (p £ 0.001). The highest enzymatic activity occurred after 72 h fermentation.
Session 99A, Biotechnology: General
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