Inducible promoters and functional genomic approaches for the genetic engineering of filamentous fungi

Abstract

In industry, filamentous fungi have a prominent position as producers of economically relevant primary or secondary metabolites. Particularly, the advent of genetic engineering of filamentous fungi has led to a growing number of molecular tools to adopt filamentous fungi for biotechnical applications. Here, we summarize recent developments in fungal biology, where fungal host systems were genetically manipulated for optimal industrial applications. Firstly, available inducible promoter systems depending on carbon sources are mentioned together with various adaptations of the Tet-Off and Tet-On systems for use in different industrial fungal host systems. Subsequently, we summarize representative examples, where diverse expression systems were used for the production of heterologous products, including proteins from mammalian systems. In addition, the progressing usage of genomics and functional genomics data for strain improvement strategies are addressed, for the identification of biosynthesis genes and their related metabolic pathways. Functional genomic data are further used to decipher genomic differences between wild-type and high-production strains, in order to optimize endogenous metabolic pathways that lead to the synthesis of pharmaceutically relevant end products. Lastly, we discuss how molecular data sets can be used to modify products for optimized applications.

Strategies and Challenges for the Development of Industrial Enzymes Using Fungal Cell Factories

“…SES consists of a promoter with a core sequence and of a heterologous transcription factor which binds to repeated activating sequences placed in the promoter (Rantasalo et al 2018). Other promoters like the Aspergillus tet-on/tet-off system are useful for research purposes rather than for industrial production (Wanka et al 2016;Kluge et al 2018). As mentioned above, a source of novel promoters may be obtained investigating mRNA levels and choosing the promoter of the highest expressed genes under relevant growth conditions.…”

Bioprocess for Production, Characteristics, and Biotechnological Applications of Fungal Phytases

“…They used gamma rays and EMS (Ethyl Methane Sulfonate) mutagenesis to enhance the activity of phytase, for which the phytase activity was improved to 387 U/mL at 45 • C. In addition, they also reported that the mutants produced through EMS displayed greater potential of phytase production when compared to the parent strain. The developing and improving production of heterologous proteins was determined under constitutive and inducible promoters' systems (Parashar and Satyanarayana, 2016;Kluge et al, 2018). The expression of phytase genes phyA and appA2 were expressed in P. pastoris (constitutive or inducible) and Saccharomyces cerevisiae (inducible) by Lei and Kim (2005).…”

Developments and opportunities in fungal strain engineering for the production of novel enzymes and enzyme cocktails for plant biomass degradation

“…Progeny with such negative characteristics would still be discarded, despite the amount of work already invested in them. In this context, directed genome manipulation can help to overcome the effect of deleterious point mutations (Kluge et al, 2018).…”