title: A novel pectin-degrading enzyme complex from Aspergillus sojae ATCC 20235 mutants.
abstract: BACKGROUND
  In the food industry, the use of pectinase preparations with high pectin esterase (PE) activity leads to the release of methanol, which is strictly regulated in food products. Herein, a pectin-degrading enzyme (PDE) complex exhibiting low PE activity of three Aspergillus sojae ATCC 20235 mutants (M3, DH56 and Guserbiot 2.230) was investigated. Production of exo-/endo-polygalacturonase (PG), exo-polymethylgalacturonase (PMG) and pectin lyase (PL) by mutant M3 and A. sojae using two different carbon sources was evaluated in solid-state fermentation. Finally, experimental preparations obtained from the mutants and commercial pectinases standardized to the same potency were screened for PDEs.
  
  
  RESULTS
  Mutant M3 grown on sugar beet was found to be the best producer of exo-PG, endo-PG, exo-PMG and PL, with maximum yields of 1111, 449, 130 and 123 U g(-1), respectively. All experimental preparations exhibited low PE activity, at least 21.5 times less than commercial pectinases, and higher endo-PG (40 U mL(-1)).
  
  
  CONCLUSIONS
  Mutant M3 was the best PDE producer using sugar beet. Mutant strains presented a PDE complex featuring high endo-PG and very low PE activities. This novel complex with low de-esterifying activity can be exploited in the food industry to degrade pectin without releasing methanol.
authors.affiliation: Downstream Bioprocessing Laboratory, School of Engineering and Science, Jacobs University, D-28759, Bremen, Germany; Centro de Biotecnología-FEMSA, Tecnológico de Monterrey, Monterrey, NL, 64849, Mexico.
authors.forename: Marco A
authors.initials: MA
authors.lastname: Mata-Gómez
authors.forename: Doreen
authors.initials: D
authors.lastname: Heerd
authors.forename: Iñigo
authors.initials: I
authors.lastname: Oyanguren-García
authors.forename: Francis
authors.initials: F
authors.lastname: Barbero
authors.forename: Marco
authors.initials: M
authors.lastname: Rito-Palomares
authors.forename: Marcelo
authors.initials: M
authors.lastname: Fernández-Lahore
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D027461:Beta vulgaris; D003470:Culture Media; D004950:Esterases / Q000378:metabolism; D004951:Esterification; D005285:Fermentation; D006801:Humans; D008190:Lyases / Q000096:biosynthesis / Q000378:metabolism; D000432:Methanol / Q000378:metabolism; D009097:Multienzyme Complexes / Q000378:metabolism*; D009154:Mutation; D010368:Pectins / Q000378:metabolism*; D011096:Polygalacturonase / Q000378:metabolism*
chemical_list: D003470:Culture Media; D009097:Multienzyme Complexes; D010368:Pectins; D004950:Esterases; D011096:Polygalacturonase; D008190:Lyases; D000432:Methanol
keywords: Aspergillus sojae; pectin esterase; pectin-degrading enzyme complex; pectinase; polygalacturonase