Table 1.
Summary of the suitable eukaryotic hosts for heterologous expression
| Host | Benefits | Handicaps | Common species |
|---|---|---|---|
| Yeast | Low-maintenance fast-growing single-cell organisms High protein expression levels Easy regulation of cell mating type (sexual or asexual) Possess typical enzymes for protein-folding and post-translational modifications Availability of robust genetic manipulation tools Ability to express membrane enzymes and secretion proteins Generally recognized as safe (GRAS) (i.e., do not produce highly toxic or oncogenic substances) | Potential hyperglycosylation at N-linked sites, which may reduce protein function Tough cell wall Low diversity of native secondary metabolites, hindering the selection of suitable precursors | Saccharomyces cerevisiae Pichia pastoris (Komagataella) Candida boidinii, Hansenula polymorpha, Pichia methanolica Yarrowia lipolytica |
| Filamentous fungi | Low-maintenance fast-growing cultures High diversity of native secondary metabolites, facilitating the selection of suitable precursors | Abundance of native metabolic pathways: production of the desired metabolite is forced to compete with the metabolism of the host Spores hazardous to health Limited expression levels | Aspergillus spp., Neurospora crassa |
| Plants | Well suited for heterologous expression of metabolic pathways from other plants Expression of large enzymes Host versatility: whole organism or a cell culture The heterologous metabolic pathway can be localized in the chloroplasts | High cost of engineering and cultivation Complex transformation protocols Low growth and reproduction rates | Nicotiana benthamiana, Nicotiana tabacum, Arabidopsis thaliana, Physcomitrella patens, Chlamydomonas reinhardtii |
| Animal cell cultures | Highly efficient viral transduction methods Efficient for expression of enzymes derived from other animals (including specific protein modifications) Absence of the cell wall, which is good for product purification | High cost of cultivation Require specific cultivation conditions and complicated equipment Low growth rate | Mammalian cells Insect cells |