title: Invertase production on solid-state fermentation by Aspergillus niger strains improved by parasexual recombination.
abstract: Invertase production by Aspergillus niger grown by solid-state fermentation was found to be higher than by conventional submerged fermentation. The haploid mutant strains Aw96-3 and Aw96-4 showed better productivity of various enzymes, as compared to wild-type parental strain A. niger C28B25. Here we use parasexual crosses of those mutants to increase further the productivity of invertase in solid-state fermentation. We isolated both a diploid (DAR2) and an autodiploid (AD96-4) strain, which were able to grow in minimal medium after mutation complementation of previously isolated haploid auxotrophic strains. Invertase production was measured in solid-state fermentation cultures, using polyurethane foam as an inert support for fungal growth. Water activity value (Aw) was adjusted to 0.96, since low Aw values are characteristic in some solid-state fermentation processes. Such diploid strains showed invertase productivity levels 5-18 times higher than levels achieved by the corresponding haploid strains. For instance, values for C28B25, Aw96-3, Aw96-4, DAR2, and AD96-4 were 441, 254, 62, 1324, and 2677 IU/(L x h), respectively. These results showed that genetic recombination, achieved through parasexual crosses in A. niger, results in improved strains with potential applications for solid-state fermentation processes.
authors.affiliation: Department of Biotechnology, Universidad Autónoma Metropolitana-Iztapalapa, Mexico DF, México.
authors.forename: Alba Mónica
authors.initials: AM
authors.lastname: Montiel-González
authors.forename: Francisco José
authors.initials: FJ
authors.lastname: Fernández
authors.forename: Gustavo
authors.initials: G
authors.lastname: Viniegra-González
authors.forename: Octavio
authors.initials: O
authors.lastname: Loera
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology* / Q000235:genetics*; D001709:Biotechnology / Q000379:methods; D004171:Diploidy; D005285:Fermentation; D006026:Glycoside Hydrolases / Q000096:biosynthesis* / Q000235:genetics; D006238:Haploidy; D007700:Kinetics; D011995:Recombination, Genetic; D043324:beta-Fructofuranosidase
chemical_list: D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase