Background
Ashbya gossypii
is a filamentous fungus widely utilized for industrial riboflavin production and has a great potential as a microbial chassis for synthesizing other valuable metabolites such as folates, biolipids, and limonene. Engineered strains of
A. gossypii
can effectively use various waste streams, including xylose-rich feedstocks. Notably,
A. gossypii
has been identified as a proficient biocatalyst for producing limonene from xylose-rich sources. This study aims to investigate the capability of engineered
A. gossypii
strains to produce various plant monoterpenes using agro-industrial waste as carbon sources.
Results
We overexpressed heterologous terpene synthases to produce acyclic, monocyclic, and bicyclic monoterpenes in two genetic backgrounds of
A. gossypii
. These backgrounds included an NPP synthase orthogonal pathway and a mutant
erg20
F95W
allele with reduced FPP synthase activity. Our findings demonstrate that
A. gossypii
can synthesize linalool, limonene, pinene, and sabinene, with terpene synthases showing differential substrate selectivity for NPP or GPP precursors. Additionally, co-overexpression of endogenous HMG1 and ERG12 with heterologous NPP synthase and terpene synthases significantly increased sabinene yields from xylose-containing media. Using mixed formulations of corn-cob lignocellulosic hydrolysates and either sugarcane or beet molasses, we achieved limonene and sabinene productions of 383 mg/L and 684.5 mg/L, respectively, the latter representing a significant improvement compared to other organisms in flask culture mode.
Conclusions
Engineered
A. gossypii
strains serve as a suitable platform for assessing plant terpene synthase functionality and substrate selectivity in vivo, which are crucial to understand monoterpene bioproduction. The NPP synthase pathway markedly enhances limonene and sabinene production in
A. gossypii
, achieving levels comparable to those of other industrial microbial producers. Furthermore, these engineered strains offer a novel approach for producing monoterpenes through the valorization of agro-industrial wastes.
Supplementary Information
The online version contains supplementary material available at 10.1186/s40694-024-00186-1.