36B-10

J. M. LOEZA-CORTE¹, S. Huerta-Ochoa¹, F. Cruz-Sosa¹, E. Favela-Torres¹, and E. J. Vernon-Carter². (1) Biotechnology, Univ. Autónoma Metropolitana Iztapalapa, San Rafael Atlixco No. 186, Col. Vicentina, Mexico City, 09340, Mexico, (2) IPH, Univ. Autónoma Metropolitana Iztapalapa, San Rafael Atlixco No. 186, Col. Vicentina, Mexico City, 09340, Mexico

L-arabinose is used as an additive in the food industry. In nature, it is found as part of the complex polysaccharides (e.g. arabinogalactans). Enzymatic hydrolysis for the production of sugars has become an increasingly important procedure in the food industry. A previous work showed that an enzymatic extract liberated L-arabinose by hydrolyzing the 1-5-a-L-arabinosyl bond of arabinogalactans. It also was established that the production of the enzymatic extract was associated to the growth of Aspergillus niger 10. The aim of this work was to optimize the production of an enzymatic extract culture medium from Aspergillus niger 10 for obtaining L-arabinose from the hydrolysis of polysaccharides. A factorial experimental design 1 x 5 (carbon – nitrogen) was utilized. In all of the treatments the fungus was incubated in a minimum medium made up by 10 g mesquite gum as carbon source, 5 levels of NaNO₃ as source of nitrogen, 1.5 g of KH₂PO₄, 0.5 g KCl and 0.5 g MgSO₄.7H₂O in 1 L of deionized water. The initial pH was adjusted to 5.6. The cultures were incubated at 30 °C during 96 h. The activity of L-arabinofuranoside was determined by adding 150 mL of the extract in 150 mL of a 4 mM solution of p-nitrophenil-a-L-arabinofuranoside in citrate-phosphate buffer (pH 5.6) during 10 min. at 40 ºC. The release of p-nitrophenol was determined by adding 900 mL of 0.1 M Na₂CO₃ and reading the absorbance at 400 nm. The experimental data indicate that the C/N ratio significantly affected the production of the enzymatic extract (p ≤ 0.01). The highest enzymatic activity and the rate of production of the enzymatic extract occurred for a C/N ratio of 10. These results indicate that it is possible to efficiently hydrolyze polysaccharides with enzymatic extracts and to obtain good yields of L-arabinose.

Session 36B, Biotechnology: General
8:30 AM - 12:00 PM, Monday AM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana