title: Improved biomass and protein production in solid-state cultures of an Aspergillus sojae strain harboring the Vitreoscilla hemoglobin.
abstract: The biotechnological value of Aspergillus sojae ATCC 20235 (A. sojae) for production of pectinases in solid-state fermentation (SSF) has been demonstrated recently. However, a common drawback of fungal solid-state cultures is the poor diffusion of oxygen into the fungi that limits its growth and biological productivity. The bacterial Vitreoscilla hemoglobin (VHb) has favored the metabolism and productivities of various bacterial and yeast strains besides alleviating hypoxic conditions of its native host, but the use of VHb in filamentous fungi still remains poor explored. Based on the known effects of VHb, this study assessed its applicability to improve A. sojae performance in SSF. The VHb gene (vgb) under control of the constitutive Aspergillus nidulants gpdA promoter was introduced into the genome of A. sojae by Agrobacterium-mediated transformation. Successful fungal transformants were identified by fluorescence microscopy and polymerase chain reaction (PCR) analyses. In solid-state cultures, the content of protease, exo-polygalacturonase (exo-PG), and exo-polymethylgalacturonase (exo-PMG) of the transformed fungus (A. sojae vgb+) improved were 26, 60, and 44 % higher, respectively, in comparison to its parental strain (A. sojae wt). Similarly, biomass content was also 1.3 times higher in the transformant strain. No significant difference was observed in endo-polygalacturonase (endo-PG) content between both fungal strains, suggesting dissimilar effects of VHb towards different enzymatic productions. Overall, our results show that biomass, protease, and exo-pectinase content of A. sojae in SSF can be improved by transformation with VHb.
authors.affiliation: Downstream Bioprocessing Lab, Jacobs University Bremen gGmbH, Bremen, Germany. r.moralugo@jacobs-university.de.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Mora-Lugo
authors.affiliation: Downstream Bioprocessing Lab, Jacobs University Bremen gGmbH, Bremen, Germany. m.madrigalvillalobos@jacobs-university.de.|Instituto Clodomiro Picado and Departamento de Bioquímica, Universidad de Costa Rica, San José, Costa Rica. m.madrigalvillalobos@jacobs-university.de.
authors.forename: Marvin
authors.initials: M
authors.lastname: Madrigal
authors.affiliation: Downstream Bioprocessing Lab, Jacobs University Bremen gGmbH, Bremen, Germany. v.yelemane@jacobs-university.de.
authors.forename: Vikas
authors.initials: V
authors.lastname: Yelemane
authors.affiliation: Downstream Bioprocessing Lab, Jacobs University Bremen gGmbH, Bremen, Germany. m.fernandez-lahore@jacobs-university.de.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Fernandez-Lahore
mesh_terms: D001230:Aspergillus / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018533:Biomass; D003470:Culture Media; D010100:Oxygen / Q000378:metabolism; D011096:Polygalacturonase / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D054793:Truncated Hemoglobins / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D011994:Recombinant Proteins; D054793:Truncated Hemoglobins; C082613:hemoglobin protein, Vitreoscilla; D011096:Polygalacturonase; D010100:Oxygen
keywords: Agrobacterium tumefaciens-mediated transformation; Aspergillus sojae; Biomass production; Pectinases and protease; Solid-state fermentation; Vitreoscilla hemoglobin