Aspergillus: A Powerful Protein Production Platform

Abstract

Aspergilli have been widely used in the production of organic acids, enzymes, and secondary metabolites for almost a century. Today, several GRAS (generally recognized as safe) Aspergillus species hold a central role in the field of industrial biotechnology with multiple profitable applications. Since the 1990s, research has focused on the use of Aspergillus species in the development of cell factories for the production of recombinant proteins mainly due to their natively high secretion capacity. Advances in the Aspergillus-specific molecular toolkit and combination of several engineering strategies (e.g., protease-deficient strains and fusions to carrier proteins) resulted in strains able to generate high titers of recombinant fungal proteins. However, the production of non-fungal proteins appears to still be inefficient due to bottlenecks in fungal expression and secretion machinery. After a brief overview of the different heterologous expression systems currently available, this review focuses on the filamentous fungi belonging to the genus Aspergillus and their use in recombinant protein production. We describe key steps in protein synthesis and secretion that may limit production efficiency in Aspergillus systems and present genetic engineering approaches and bioprocessing strategies that have been adopted in order to improve recombinant protein titers and expand the potential of Aspergilli as competitive production platforms.

The ancient koji mold (Aspergillus oryzae) as a modern biotechnological tool

“…Being listed as GRAS by the FDA, and due to its potent secretion machinery, A. oryzae is an excellent host for industrial protein production such as amylases, chymosin, glucose oxidases, cellulases, lipases, pectinases, catalases, proteases, phytases, and xylanases in food (He et al 2018a;Ntana et al 2020). As a result, A. oryzae has been attracting continuous attention as a host for expressing homologous and heterologous proteins.…”

Engineered Fungus Thermothelomyces thermophilus Producing Plant Storage Proteins

“…A protein produced in microbial cells of bacteria, fungi or algae (single-cell protein) can be used to improve the protein content in animal feed [1,5,[14][15][16]. Of the various methods available to producers, supplementation of deficient nutrients in the form of biomass after enzymatic treatment of lignocellulolytic fungi, combined with chemical and physical treatments, has been shown to be effective for utilization of low-quality forages, such as cereal straws and other agro-industrial wastes [14].…”

“…They produce essential nutrients, such as thiamine, riboflavin, biotin, niacin, pantothenic acid, pyridoxine, choline, streptogenin, glutathione, folic acid, and p-amino benzoic acid, as well as fiber (cell wall glucans) that contribute to the diet. In addition, the filamentous fungi have a moderate nucleic acid content (7-10%) in comparison with bacteria and yeasts; what is more, yeasts tend to produce undesired hypermannosylated secreted proteins [15,16]. The fungal biomass of Aspergillus oryzae, Neurospora intermedia, and Rizhopus oryzae grown on vinasse and comparable with the fishmeal AA content and profile were suggested as supplementation alternative for fish feeding [17].…”

Sustainable Combination Mechanism for Catalysts: A Game-Theoretical Approach

“…Applying the endo-mannanases in combination with CTec2 for lignocellulose degradation led to synergism, with a 1.3-fold increase in reducing sugar release as compared to when CTec2 was used alone; advances in the Aspergillus-specific molecular toolkit and combination of several engineering strategies resulted in strains that were able to generate high titers of recombinant fungal proteins. Ntana et al [5] described key steps in protein synthesis and secretion that may limit the production efficiency in Aspergillus systems and present genetic engineering approaches and bioprocessing strategies that have been adopted in order to improve recombinant protein titers and expand the potential of Aspergilli as competitive production platforms; single-atom catalysts (SACs), consisting of metals atomically dispersed on a support, are considered as advanced materials bridging homogeneous and heterogeneous catalysis, representing the catalysis at the limit. The enhanced performance of these catalysts is due to the combination of distinct factors.…”