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Keywords:

  • Ashbya gossypii;
  • Aspergillus niger β-galactosidase;
  • recombinant β-galactosidase secretion;
  • A. gossypii GPD and TEF promoters;
  • Saccharomyces cerevisiae PGK1 and ADH1 promoters

Ashbya gossypii has been recently considered as a host for the expression of recombinant proteins. The production levels achieved thus far were similar to those obtained with Saccharomyces cerevisiae for the same proteins. Here, the β-galactosidase from Aspergillus niger was successfully expressed and secreted by A. gossypii from 2-µm plasmids carrying the native signal sequence at higher levels than those secreted by S. cerevisiae laboratorial strains. Four different constitutive promoters were used to regulate the expression of β-galactosidase: A. gossypii AgTEF and AgGPD promoters, and S. cerevisiae ScADH1 and ScPGK1 promoters. The native AgTEF promoter drove the highest expression levels of recombinant β-galactosidase in A. gossypii, leading to 2- and 8-fold higher extracellular activity than the AgGPD promoter and the heterologous promoters, respectively. In similar production conditions, the levels of active β-galactosidase secreted by A. gossypii were up to 37 times higher than those secreted by recombinant S. cerevisiae and ∼2.5 times higher than those previously reported for the β-galactosidase-high producing S. cerevisiae NCYC869-A3/pVK1.1. The substitution of glucose by glycerol in the production medium led to a 1.5-fold increase in the secretion of active β-galactosidase by A. gossypii. Recombinant β-galactosidase secreted by A. gossypii was extensively glycosylated, as are the native A. niger β-galactosidase and recombinant β-galactosidase produced by yeast. These results highlight the potential of A. gossypii as a recombinant protein producer and open new perspectives to further optimize recombinant protein secretion in this fungus. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 30:261–268, 2014