Project description:Polyketide synthases (PKSs) are modular enzymes with exceptional potential as biocatalysts for producing non-native compounds. Here, we report the first PKS-based pathway for adipic acid (AA), an industrial monomer for nylon production, by engineering one of the most extensively hybridized PKS systems to date. Using a retrobiosynthetic approach, we identified EtnB, a succinyl-CoA loading module that uniquely retains the terminal carboxyl group, enabling access to dicarboxylic polyketide products, rarely produced by canonical PKSs. EtnB was coupled to a fully reducing extension module through an engineered communication linker, which improved ACP–KS interactions, enhanced titers, and demonstrated selective S-CoA loading in vivo. This construct integrates genes from five organisms, seven PKS modules joined across six non-natural junctions, and functions in both Escherichia coli and Pseudomonas putida. Additional engineering that included AT domain swaps, optimization of extender unit supply, and host strain metabolic rewiring further improved AA titers into the low mg/L range. Together, this work demonstrates that highly chimeric PKSs can be rendered functional through rational design, expands the PKS toolkit with a carboxyl-retaining loading module, and establishes a versatile platform for engineering diacids and other non-canonical products through PKS pathways.
Project description:Producing the fuels and chemicals from renewable plant biomass has been thought as a feasible way for global sustainable development. However, the economical efficiency of biorefinery remains challenges. Here a cellulolytic thermophilic fungus, Myceliophthora thermophila, was constructed into a platform through metabolic engineering, which can efficiently convert lignocellulose to important bulk chemicals for polymers, four carbon 1, 4-diacids (malic and succinic acid), directly from lignocellulose without any extra enzymes addition or complicated pretreatment, with titer of over 200 g/L on cellulose and 110 g/L on plant biomass (corncob) during fed-batch fermentation. Our study represents a milestone of consolidated bioprocessing technology (CBP) and offers a new promising system for cost-effectively production of biomass-based chemicals and potentially fuels.
Project description:Genetic engineering of filamentous fungi has promise for accelerating the transition to a more sustainable food system and enhancing the nutritional value, sensory appeal, and scalability of microbial foods. However, genetic tools and demonstrated use cases for bioengineered food production by edible strains are lacking. Here, we developed a synthetic biology toolkit for Aspergillus oryzae, an edible fungus traditionally used in fermented foods and currently used in protein production and meat alternatives. Our toolkit includes a CRISPR-Cas9 method for genome integration, neutral loci, and new promoters. We use these tools to enhance the elevate levels of the nutraceutical ergothioneine and intracellular heme in the edible biomass. The biomass overproducing heme is red in color and is readily formulated into imitation meat patties with minimal processing. These findings highlight the promise of genetic approaches to enhance fungal meat alternatives and provide useful engineering tools for diverse applications in fungal food production and beyond.
Project description:In this project we aim to construct a tyrosine-producing E. coli strain through iterative steps of genome engineering. High PEP availability through knockout of the PTS was combined with the precise, in-place genomic integration of several engineering interventions, known to increase L-tyrosine production yields, to create a tyrosine-overproducing E. coli strain that can function as a platform for further engineering and optimization. Utilizing a design-build-test-learn (DBTL) cycle, an evolved pts-knockout E. coli strain was equipped with optimizations of the aroG, aroB and tyrA genes and cultivated under batch and fed-batch conditions. Subsequently, metabolomics, transcriptomics and proteomics samples from the fed-batch experiments were analyzed to inform the design of new genomic interventions.
Project description:Bacterial cellulose (BC) represents a renewable biomaterial with unique properties promising for biotechnology and biomedicine. Komagataeibacter hansenii ATCC 53,582 is a well-characterized high-yield producer of BC used in the industry. Its genome encodes three distinct cellulose synthases (CS), bcsAB1, bcsAB2, and bcsAB3, which together with genes for accessory proteins are organized in operons of different complexity. The genetic foundation of its high celluloseproducing phenotype was investigated by constructing chromosomal in-frame deletions of the CSs and of two predicted regulatory diguanylate cyclases (DGC), dgcA and dgcB. Proteomic characterization suggested that BcsAB1 was the decisive CS because of its high expression and its exclusive contribution to the formation of microcrystalline cellulose. BcsAB2 showed a lower expression level but contributes significantly to the tensile strength of BC and alters fiber diameter significantly as judged by scanning electron microscopy. Nevertheless, no distinct extracellular polymeric substance (EPS) from this operon was identified after static cultivation. Although transcription of bcsAB3 was observed, expression of the protein was below the detection limit of proteome analysis. Alike BcsAB2, deletion of BcsAB3 resulted in a visible reduction of the cellulose fiber diameter. The high abundance of BcsD and the accessory proteins CmcAx, CcpAx, and BglxA emphasizes their importance for the proper formation of the cellulosic network. Characterization of deletion mutants lacking the DGC genes dgcA and dgcB suggests a new regulatory mechanism of cellulose synthesis and cell motility in K. hansenii ATCC 53,582. Our findings form the basis for rational tailoring of the characteristics of BC.
Project description:Engineering native gut bacteria offers a route to persistent, programmable therapeutic delivery in the gut, yet many dominant taxa remain genetically intractable. Lachnospiraceae are a prevalent and abundant family in the human gut microbiome that produce metabolites linked to intestinal and metabolic health1. Despite their promise as engineered live biotherapeutics, genetic manipulation of Lachnospiraceae remains challenging. Here, we develop a modular toolkit for Lachnospiraceae engineering, including constitutive and inducible expression and chromosomal integration systems. Applying this toolkit to the native commensal Coprococcus comes, we program secretion of the mammalian cytokine interleukin-22 (IL-22) in the mouse intestinal tract, where it induces epithelial defense transcriptional programs. In a mouse model of metabolic dysfunction-associated steatotic liver disease, IL-22–secreting C. comes improves glucose homeostasis, reduces systemic endotoxemia and attenuates hepatic steatosis. This work demonstrates that a native Lachnospiraceae chassis can be genetically programmed to modulate host metabolic and immune physiology. The toolkit provides a foundation for Lachnospiraceae-derived microbiome therapeutics and for dissecting causal relationships between commensal gene programs and host physiology.
Project description:Engineering native gut bacteria offers a route to persistent, programmable therapeutic delivery in the gut, yet many dominant taxa remain genetically intractable. Lachnospiraceae are a prevalent and abundant family in the human gut microbiome that produce metabolites linked to intestinal and metabolic health1. Despite their promise as engineered live biotherapeutics, genetic manipulation of Lachnospiraceae remains challenging. Here, we develop a modular toolkit for Lachnospiraceae engineering, including constitutive and inducible expression and chromosomal integration systems. Applying this toolkit to the native commensal Coprococcus comes, we program secretion of the mammalian cytokine interleukin-22 (IL-22) in the mouse intestinal tract, where it induces epithelial defense transcriptional programs. In a mouse model of metabolic dysfunction-associated steatotic liver disease, IL-22–secreting C. comes improves glucose homeostasis, reduces systemic endotoxemia and attenuates hepatic steatosis. This work demonstrates that a native Lachnospiraceae chassis can be genetically programmed to modulate host metabolic and immune physiology. The toolkit provides a foundation for Lachnospiraceae-derived microbiome therapeutics and for dissecting causal relationships between commensal gene programs and host physiology.