36B-26

R. M. RODRIGUEZ-JASSO, Food Research Dept. School of Chemistry, Univ. Autonoma de Coahuila, PO Box 252, Saltillo, 25000, Mexico, H. A. Ruíz-Leza, Univ. Autonoma de Coahuila, Food Research Dept. School of Chemistry, PO Box 252, Saltillo, Coahuila, 25000, Mexico, G. Aguilar, Univ. Nacional Autonoma de Mexico, Dept. de Alimentos y Biotecnología. Facultad de Química, Mexico, DF, Mexico, R. Rodriguez-Herrera, Food Research Dept. School of Chemistry., Univ. Autónoma de Coahuila, PO Box 252, Saltillo, Coahuila, 25001, Mexico, C. N. Aguilar, Univ. Autonoma de Cohuila, Food Research Dept. School of Chemistry, PO Box 252, Saltillo, Coahuila, 25000, E. Favela-Torres, Biotechnology, Univ. Autónoma Metropolitana Iztapalapa, San Rafael Atlixco # 186, Mexico City, 09340, and J. C. Contreras-Esquivel, Food Research Dept. School of Chemistry, Univ. Autónoma de Coahuila, PO Box 252, Saltillo, Coahuila, 25000, Mexico.

Rhamnogalacturonases (RHG) are pectic enzymes that degrade the branched regions of pectin, which consist of alternated galacturonic acid and rhamnose residues with neutral sugars side chains. Complete degradation of pectin is of great importance for various industrial processes such as clarification of fruit juices, but principally the use of this specific enzyme allow the characterization of unknown rhamnogalacturonan (RG) fragments. Most commercial pectinolytic enzyme preparations are produced by fermentation with filamentous fungi. However, the majority of the studies have been based in production of homogalacturonan-degrading enzymes. The main objective of this work is to find RHG activity in Mexican strains by submerged fermentation (SmF). Five microorganisms of Aspergillus and Penicillum genus were used. The carbon and nitrogen source were soy RG (10 g/L) and peptone (5 g/L). The fermentation conditions were 175 rpm and 30° C. After 45 h, RHG activity was measured by a plate assay and colorimetric technique with azo-RG. Twelve commercial enzyme preparations were screened for RHG activity. The pH at the end of fermentation were up to 7 in almost all the strains. Biomass values were between 1-1.5 g/L for Aspergillus strains, but in Penicillum strain were 0.5 g/L. In plate screening Aspergillus FP370, Aspergillus FP390 and Penicillium EH3 showed the formation of a white halo, as an indication of RHG activity. The same strains showed absorbance values of 0.25 nm in contrast with 0.55 nm of the standard. All the standard enzymes present RHG activity. In conclusion, the azo-dye technique allow to determinate RHG activity in three Mexican strains. This fungal strains can be used in submerged or solid fermentation for the production and purification of novel RHG enzymes.

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