Heterologous production of the widely used natural food colorant carminic acid in Aspergillus nidulans

Abstract

The natural red food colorants carmine (E120) and carminic acid are currently produced from scale insects. The access to raw material is limited and current production is sensitive to fluctuation in weather conditions. A cheaper and more stable supply is therefore desirable. Here we present the first proof-of-concept of heterologous microbial production of carminic acid in Aspergillus nidulans by developing a semi-natural biosynthetic pathway. Formation of the tricyclic core of carminic acid is achieved via a two-step process wherein a plant type III polyketide synthase (PKS) forms a non-reduced linear octaketide, which subsequently is folded into the desired flavokermesic acid anthrone (FKA) structure by a cyclase and a aromatase from a bacterial type II PKS system. The formed FKA is oxidized to flavokermesic acid and kermesic acid, catalyzed by endogenous A. nidulans monooxygenases, and further converted to dcII and carminic acid by the Dactylopius coccus C-glucosyltransferase DcUGT2. The establishment of a functional biosynthetic carminic acid pathway in A. nidulans serves as an important step towards industrial-scale production of carminic acid via liquid-state fermentation using a microbial cell factory.

Sustainable bioproduction of the blue pigment indigoidine: Expanding the range of heterologous products inR. toruloidesto include non-ribosomal peptides

“…Microbial production of dyes has the potential to circumvent the issues with chemical synthesis and can also provide higher production levels and purity than can be achieved by isolating these dyes from natural sources. 6,7 Indigoidine is a natural blue pigment produced by several bacteria via known biosynthetic gene clusters. [8][9][10][11][12] This 3′,3′-bipyridyl pigment is formed through condensation of two molecules of L-glutamine catalyzed by a non-ribosomal peptide synthetase (NRPS).…”

Moulding the mould: understanding and reprogramming filamentous fungal growth and morphogenesis for next generation cell factories

“…Other than CRISPR–Cas, what other synthetic tools and techniques promise to revolutionise fungal cell factories, both from morphological perspectives and for increasing the associated product portfolio? Several filamentous fungi have been engineered to heterologously express key natural product biosynthetic genes, such as those encoding nonribosomal peptide synthetases, or polyketide synthases, including A. nidulans [132, 133], A. oryzae [134], A. niger [6], and P. chrysogenum [135], amongst others. Excitingly, new-to-nature compounds can also be generated, either by swapping of enzyme domains, subunits, or modules [136, 137], or by feeding various amino acid precursors in growth media, which are incorporated into nonribosomal peptide molecules [6].…”

Selecting for useful properties of plants and fungi – Novel approaches, opportunities, and challenges

“…Chimeric enzymes and combinatorial expression of biosynthetic genes can also result in novel derivatives of known compounds as shown for fungal macrolide lactones with potential anti‐tumor, anti‐malarial, and anti‐bacterial activities (Xu, Jiang, Zhang, Ma, & Guo, 2014a; Xu, Zhou, et al, 2014) and fungal cyclodepsipeptides with novel antiparasitic activity to treat, for example, the potentially fatal Chagas disease and Leishmaniasis (Steiniger et al., 2017). Indeed, combining genes from different pathways is a very promising approach to increase the diversity of chemicals produced by fungi (Frandsen et al., 2018; Li et al., 2018). Yet although scalable platforms for heterologous expression in fungal strains are becoming available (Harvey et al., 2018), optimization is needed to consistently reach high production levels.…”