Synthetic Pathway for the Production of Olivetolic Acid in Escherichia coli

Discovery of major QTL and a massive haplotype associated with cannabinoid biosynthesis in drug-type Cannabis

Cannabis (Cannabis sativa L.), once sidelined by decades of prohibition, has now gained recognition as a multifaceted and promising plant in both medical research and commercial applications following its recent legalization. This study leverages a genome-wide association study (GWAS) on 174 drug-type Cannabis accessions from the legal Canadian market, focusing on identifying quantitative trait loci (QTL) and candidate genes associated with eleven cannabinoid traits using 282K common single-nucleotide polymorphisms. This approach aims to transform our understanding of Cannabis genetics. We have pinpointed 33 significant markers that significantly influence cannabinoid production, promising to drive the development of Cannabis varieties with specific cannabinoid profiles. Among the notable findings is a massive haplotype of ∼60 Mb on chromosome 7 in Type I (i.e., tetrahydrocannabinol [THC]-dominant) accessions, highlighting a major genetic influence on cannabinoid profiles. These insights offer valuable guidance for Cannabis breeding programs, enabling the use of precise genetic markers to select and refine promising Cannabis varieties. This approach promises to speed up the breeding process, reduce costs significantly compared to traditional methods, and ensure that the resulting Cannabis varieties are optimized for specific medical and recreational needs. This study marks a significant stride toward fully integrating Cannabis into modern agricultural practices and genetic research, paving the way for future innovations.

Biosynthesis of novel cannabigerolic acid derivatives by engineering the substrate specificity of aromatic prenyltransferase

Introduction

Cannabinoids possess significant therapeutic potential, but their natural chemical diversity derived from plant biosynthesis is limited. Efficient biotransformation processes are required to expand the range of accessible cannabinoids. This study aimed to enhance the selective biosynthesis of cannabigerolic acid (CBGA) and its derivatives with varying aliphatic chain lengths, which serve as key precursors to various cannabinoids.

Methods

We employed computational modeling and structure-guided mutagenesis to engineer the aromatic prenyltransferase NphB. Mutants were designed via in silico docking analyses to optimize substrate orientation and catalytic distance. The variants were expressed in E. coli, and their catalytic efficiencies were evaluated through in vivo whole-cell and in vitro enzymatic assays. Products were identified and quantified by UHPLC-MS.

Results

Engineered NphB variants exhibited significant improvements, with triple mutants achieving a 7-fold increase in CBGA production and a 4-fold increase in cannabigerovarinic acid production. Additionally, a single mutant also enhanced the synthesis of 3-geranyl orsellinic acid by 1.3-fold. Notably, novel enzymatic activity was identified that enabled the biosynthesis of 3-geranyl-2,4-dihydroxybenzoic acid. Structural analyses revealed that the mutations improved the spatial positioning of aromatic substrates relative to the co-substrate geranyl pyrophosphate.

Discussion

This study demonstrates the feasibility of enzyme design to tailor prenyltransferase specificity for the production of diverse CBGA derivatives. These findings lay the groundwork for the microbial production of novel cannabinoids and offer promising potential for the development of scalable biocatalytic systems for therapeutic and industrial applications.

Efficient Escherichia coli Platform for Cannabinoid Precursor Olivetolic Acid Biosynthesis from Inexpensive Inputs

Olivetolic acid (OLA), an initial precursor of cannabinoids, is catalyzed by type III polyketide synthase, which has a wide range of pharmacological activities, such as antimicrobial and cytotoxic effects. Here, we applied systematic metabolic engineering to develop a multienzyme cascade system to produce OLA via two low-cost inputs. The polyketide synthase (OLS) and cyclase enzymes (OAC), along with the best combination of hexanoyl-CoA and malonyl-CoA synthetases (AEE3 and MatB), were first introduced into the biocatalytic system to increase the supply of hexanoyl-CoA and malonyl-CoA as starting and extender units. To drive the catalysis smoothly, an ATP regeneration system and a CoA-sufficient supply system were incorporated into the biocatalysts to provide enough cofactors. Furthermore, malonyl-CoA flux was redirected to OLA biosynthesis through delicate control of the fatty acid biosynthesis (FAB) pathway via promoter engineering. Collectively, these strategies have led us to produce OLA at a titer of 102.1 mg/L with a productivity of 25.5 mg/L/h by using malonate and hexanoate as direct substrates. Our biocatalytic system provides an effective platform for the production of the cannabinoid precursor OLA in Escherichia coli and may be a valuable reference for the development of microbial cell factories that use hexanoyl-CoA and malonyl-CoA as important intermediates.

A new cannabigerolic acid derivative and its unprenylated precursor produced through the reconstitution of cannabinoid biosynthesis in Streptomyces

A new derivative of cannabigerolic acid, designated as iso-cannabigerolic acid (iso-CBGA), a member of the cannabinoid family, and its precursor iso-olivetolic acid (iso-OA) were discovered from the culture of the engineered Streptomyces avermitilis heterologously expressing the genes responsible for cannabigerolic acid biosynthesis. Structural determination revealed an iso-pentyl moiety, which may arise from the biosynthetic precursor pool present in S. avermitilis. We describe herein the culture, isolation, structure determination and antibacterial activities of iso-CBGA and iso-OA.

Is nitrogen-modified atmosphere packaging a tool for retention of volatile terpenes and cannabinoids in stored Cannabis sativa inflorescence?

Modified atmosphere packaging (MAP) alters the gaseous composition of air surrounding packaged goods to prevent deleterious oxidation associated reactions. MAP has been adopted for the storage of cannabis, though a recent study revealed little difference in terpene content under MAP conditions. Questions regarding its efficacy for preservation of high value compounds like terpenes and cannabinoids lost during postharvest storage remain. The goal of this research is to determine weather N2 MAP preserves high value compounds of cannabis during its postharvest storage. This experiment followed a completed randomized block design. There were two factors of interest. The first was storage atmosphere (atmospheric or N2 MAP). The second was storage duration (18, 46, or 74 days). The experiment was then blocked by cannabis chemovar using 5 different chemovars. The concentration of 17 cannabinoids was evaluated through UPLC-UV and 61 volatile terpene compounds through GC-MS. Concentrations were compared over time and between storage treatments. There were no significant differences in total cannabinoids and volatile terpene compounds over time or between storage treatments. Individual cannabinoids Δ9-THC, CBG, CBNA, CBC, THCV, and THCVA all increased during storage time while THCA decreased. CBG and THCV only increased under MAP storage. Individual aromatics limonene, β-pinene, α-pinene, camphene, and terpinolene all only decreased during storage under N2 MAP. Only caryophyllene oxide and α-humulene increased under N2 MAP storage. β-Myrcene decreased under atmospheric storage, but not under N2 MAP. While N2 MAP had no effect on the preservation of total cannabinoids and aromatics during storage, it did influence several individual compounds. CBG, THCV, and α-humulene all increased under N2 MAP. N2 MAP also maintained the concentration β-myrcene over time, though the preservation of β-myrcene was offset by a decrease limonene. Overall, N2 MAP was not needed for preservation of most high value compounds but did have an effect of some compounds with reputed therapeutic benefits.

Improving CsOAC Activity in Saccharomyces cerevisiae for Directed Production of Olivetolic Acid through Rational Design

Olivetolic acid (OA) is an essential precursor in the cannabinoid biosynthesis. It is produced through a unique interaction between the two proteins, olivetol synthase (CsOLS) and olivetolic acid cyclase (CsOAC). When the OA biosynthesis is transferred to Saccharomyces cerevisiae, olivetol (OL) is produced as a side product, even with a high enhancement of copy number of CsOAC. In order to increase the OA titer while decreasing the OL titer in S. cerevisiae, rational design was applied to CsOAC using in silico approaches such as protein-ligand docking to find potential protein variants. In vivo screening and also testing different approaches for both proteins was applied to identify the best performing variants of CsOAC. Four variants were identified that gave the desired properties. The best CsOAC variant, G82 A/L92Y, resulted in a 1.7-fold increase in OA production and a shift in the ratio between the two products towards OA.

Identification and Optimization of more Efficient Olivetolic Acid Synthases

Introduction: Olivetolic acid (OLA) is a key intermediate in cannabidiol (CBD) synthesis, and cannabinoids are important neuroactive drugs. However, the catalytic activity of olivetolic acid synthase (OLS), the key enzyme involved in OLA biosynthesis, remains low and its catalytic mechanism is unclear. Materials and Methods: In this study, we conducted a scrupulous screening of the pivotal rate-limiting enzyme and analyzed its amino acid sites that are critical to enzyme activity as validated by experiments. Results: Through stringent enzyme screening, we pinpointed a highly active OLS sequence, OLS4. Then, we narrowed down three critical amino acid sites (I258, D198, E196) that significantly influence the OLS activity. Conclusions: Our findings laid the groundwork for the efficient biosynthesis of OLA, and thereby facilitate the biosynthesis of CBD.

Advancement of Research Progress on Synthesis Mechanism of Cannabidiol (CBD)

Cannabis sativa L. is a multipurpose crop with high value for food, textiles, and other industries. Its secondary metabolites, including cannabidiol (CBD), have potential for broad application in medicine. With the CBD market expanding, traditional production may not be sufficient. Here we review the potential for the production of CBD using biotechnology. We describe the chemical and biological synthesis of cannabinoids, the associated enzymes, and the application of metabolic engineering, synthetic biology, and heterologous expression to increasing production of CBD.

Establishing an Artificial Pathway for the Biosynthesis of Octopamine and Synephrine

In this study, we designed an artificial pathway composed of tyramine β-hydroxylase (TBH) and phenylethanolamine N-methyltransferase (PNMT) for the biosynthesis of both octopamine and synephrine. As most TBH and PNMT originate from eukaryotic animals and plants, the heterologous expression and identification of functional TBH and PNMT are critical for establishing the pathway in mode microorganisms like Escherichia coli. Here, three TBHs were evaluated, and only TBH from Drosophila melanogaster was successfully expressed in the soluble form in E. coli. Its expression was promoted by evaluating the effects of different expression strategies. The specific enzyme activity of TBH was optimized up to 229.50 U·g-1, and the first step in the biosynthetic pathway was successfully established and converted tyramine to synthesize 0.10 g/L of octopamine. Furthermore, the second step to produce synephrine from octopamine was developed by screening PNMT, enhancing enzyme activity, and optimizing reaction conditions, with a maximum synephrine production of 2.02 g/L. Finally, based on the optimization of the reaction conditions for each individual reaction, the one-pot cascade reaction for synthesizing synephrine from tyramine was constructed by combining the TBH and PNMT. The synthetic synephrine reached 30.05 mg/L with tyramine as substrate in the two-step enzyme cascade system. With further optimization and amplification, the titers of octopamine and synephrine were increased to 0.45 and 0.20 g/L, respectively, with tyramine as substrate. This work was the first achievement of the biosynthesis of octopamine and synephrine to date.

Discovery of Latent Cannabichromene Cyclase Activity in Marine Bacterial Flavoenzymes

Production of phytocannabinoids remains an area of active scientific interest due to the growing use of cannabis by the public and the underexplored therapeutic potential of the over 100 minor cannabinoids. While phytocannabinoids are biosynthesized by Cannabis sativa and other select plants and fungi, structural analogs and stereoisomers can only be accessed synthetically or through heterologous expression. To date, the bioproduction of cannabinoids has required eukaryotic hosts like yeast since key, native oxidative cyclization enzymes do not express well in bacterial hosts. Here, we report that two marine bacterial flavoenzymes, Clz9 and Tcz9, perform oxidative cyclization reactions on phytocannabinoid precursors to efficiently generate cannabichromene scaffolds. Furthermore, Clz9 and Tcz9 express robustly in bacteria and display significant tolerance to organic solvent and high substrate loading, thereby enabling fermentative production of cannabichromenic acid in Escherichia coli and indicating their potential for biocatalyst development.

Engineering functional materials through bacteria-assisted living grafting

Functionalizing materials with biomacromolecules such as enzymes has broad applications in biotechnology and biomedicine. Here, we introduce a grafting method mediated by living cells to functionalize materials. We use polymeric scaffolds to trap engineered bacteria and micron-sized particles with chemical groups serving as active sites for grafting. The bacteria synthesize the desired protein for grafting and autonomously lyse to release it. The released functional moieties are locally grafted onto the active sites, generating the materials engineered by living grafting (MELGs). MELGs are resilient to perturbations because of both the bonding and the regeneration of functional domains synthesized by living cells. The programmability of the bacteria enables us to fabricate MELGs that can respond to external input, decompose a pollutant, reconstitute synthetic pathways for natural product synthesis, and purify mismatched DNA. Our work establishes a bacteria-assisted grafting strategy to functionalize materials with a broad range of biological activities in an integrated, flexible, and modular manner. A record of this paper's transparent peer review process is included in the supplemental information.

Snowprint: a predictive tool for genetic biosensor discovery

Bioengineers increasingly rely on ligand-inducible transcription regulators for chemical-responsive control of gene expression, yet the number of regulators available is limited. Novel regulators can be mined from genomes, but an inadequate understanding of their DNA specificity complicates genetic design. Here we present Snowprint, a simple yet powerful bioinformatic tool for predicting regulator:operator interactions. Benchmarking results demonstrate that Snowprint predictions are significantly similar for >45% of experimentally validated regulator:operator pairs from organisms across nine phyla and for regulators that span five distinct structural families. We then use Snowprint to design promoters for 33 previously uncharacterized regulators sourced from diverse phylogenies, of which 28 are shown to influence gene expression and 24 produce a >20-fold dynamic range. A panel of the newly repurposed regulators are then screened for response to biomanufacturing-relevant compounds, yielding new sensors for a polyketide (olivetolic acid), terpene (geraniol), steroid (ursodiol), and alkaloid (tetrahydropapaverine) with induction ratios up to 10.7-fold. Snowprint represents a unique, protein-agnostic tool that greatly facilitates the discovery of ligand-inducible transcriptional regulators for bioengineering applications. A web-accessible version of Snowprint is available at https://snowprint.groov.bio .

Engineering cannabinoid production in Saccharomyces cerevisiae

Phytocannabinoids are natural products with highly interesting pharmacological properties mainly produced by plants. The production of cannabinoids in a heterologous host system has gained interest in recent years as a promising alternative to production from plant material. However, the systems reported so far do not achieve industrially relevant titers, highlighting the need for alternative systems. Here, we show the production of the cannabinoids cannabigerolic acid and cannabigerol from glucose and hexanoic acid in a heterologous yeast system using the aromatic prenyltransferase NphB from Streptomyces sp. strain CL190. The production was significantly increased by introducing a fusion protein consisting of ERG20WW and NphB. Furthermore, we improved the production of the precursor olivetolic acid to a titer of 56 mg L-1 . The implementation of the cannabinoid synthase genes enabled the production of Δ9 -tetrahydrocannabinolic acid, cannabidiolic acid as well as cannabichromenic acid, where the heterologous biosynthesis of cannabichromenic acid in a yeast system was demonstrated for the first time. In addition, we found that the product spectrum of the cannabinoid synthases localized to the vacuoles of the yeast cells was highly dependent on extracellular pH, allowing for easy manipulation. Finally, using a fed-batch approach, we showed cannabigerolic acid and olivetolic acid titers of up to 18.2 mg L-1 and 117 mg L-1 , respectively.

Dual cytoplasmic-peroxisomal compartmentalization engineering and multiple metabolic engineering strategies for high yield non-psychoactive cannabinoid in Saccharomyces cerevisiae

CBG (Cannabigerol), a nonpsychoactive cannabinoid, has garnered attention due to its extensive antimicrobial and anti-inflammatory properties. However, the natural content of CBG in Cannabis sativa L. is minimal. In this study, we developed an engineered cell factory for CBG production using Saccharomyces cerevisiae. We introduced the CBGA biosynthetic pathway into S. cerevisiae and employed several strategies to enhance CBGA production. These strategies included dynamically inhibiting the competitive bypass of key metabolic pathways regulated by Erg20p. Additionally, we implemented a dual cytoplasmic-peroxisomal compartmentalization approach to further increase CBGA production. Furthermore, we ensured efficient CBGA production by optimizing NADPH and acetyl-CoA pools. Ultimately, our engineered strain achieved a CBG titer of 138 mg L-1 through fed-batch fermentation in a 5 L bioreactor, facilitated by microwave decarboxylation extraction. These findings underscore the significant potential of yeast cell factories for achieving higher yields in cannabinoid production.

Bioengineering of the Marine Diatom Phaeodactylum tricornutum with Cannabis Genes Enables the Production of the Cannabinoid Precursor, Olivetolic Acid

The increasing demand for novel natural compounds has prompted the exploration of innovative approaches in bioengineering. This study investigates the bioengineering potential of the marine diatom Phaeodactylum tricornutum through the introduction of cannabis genes, specifically, tetraketide synthase (TKS), and olivetolic acid cyclase (OAC), for the production of the cannabinoid precursor, olivetolic acid (OA). P. tricornutum is a promising biotechnological platform due to its fast growth rate, amenability to genetic manipulation, and ability to produce valuable compounds. Through genetic engineering techniques, we successfully integrated the cannabis genes TKS and OAC into the diatom. P. tricornutum transconjugants expressing these genes showed the production of the recombinant TKS and OAC enzymes, detected via Western blot analysis, and the production of cannabinoids precursor (OA) detected using the HPLC/UV spectrum when compared to the wild-type strain. Quantitative analysis revealed significant olivetolic acid accumulation (0.6-2.6 mg/L), demonstrating the successful integration and functionality of the heterologous genes. Furthermore, the introduction of TKS and OAC genes led to the synthesis of novel molecules, potentially expanding the repertoire of bioactive compounds accessible through diatom-based biotechnology. This study demonstrates the successful bioengineering of P. tricornutum with cannabis genes, enabling the production of OA as a precursor for cannabinoid production and the synthesis of novel molecules with potential pharmaceutical applications.

Development of an efficient yeast platform for cannabigerolic acid biosynthesis

Cannabinoids are important therapeutical molecules for human ailments, cancer treatment, and SARS-CoV-2. The central cannabinoid, cannabigerolic acid (CBGA), is generated from geranyl pyrophosphate and olivetolic acid by Cannabis sativa prenyltransferase (CsPT4). Despite efforts to engineer microorganisms such as Saccharomyces cerevisiae (S. cerevisiae) for CBGA production, their titers remain suboptimal because of the low conversion of hexanoate into olivetolic acid and the limited activity and stability of the CsPT4. To address the low hexanoate conversion, we eliminated hexanoate consumption by the beta-oxidation pathway and reduced its incorporation into fatty acids. To address CsPT4 limitations, we expanded the endoplasmic reticulum and fused an auxiliary protein to CsPT4. Consequently, the engineered S. cerevisiae chassis showed a marked improvement of 78.64-fold in CBGA production, reaching a titer of 510.32 ± 10.70 mg l-1 from glucose and hexanoate.

Cannabis sativa: origin and history, glandular trichome development, and cannabinoid biosynthesis

Is Cannabis a boon or bane? Cannabis sativa has long been a versatile crop for fiber extraction (industrial hemp), traditional Chinese medicine (hemp seeds), and recreational drugs (marijuana). Cannabis faced global prohibition in the twentieth century because of the psychoactive properties of ∆9-tetrahydrocannabinol; however, recently, the perspective has changed with the recognition of additional therapeutic values, particularly the pharmacological potential of cannabidiol. A comprehensive understanding of the underlying mechanism of cannabinoid biosynthesis is necessary to cultivate and promote globally the medicinal application of Cannabis resources. Here, we comprehensively review the historical usage of Cannabis, biosynthesis of trichome-specific cannabinoids, regulatory network of trichome development, and synthetic biology of cannabinoids. This review provides valuable insights into the efficient biosynthesis and green production of cannabinoids, and the development and utilization of novel Cannabis varieties.

Harnessing the advances of genetic engineering in microalgae for the production of cannabinoids

Cannabis is widely recognized as a medicinal plant owing to bioactive cannabinoids. However, it is still considered a narcotic plant, making it hard to be accessed. Since the biosynthetic pathway of cannabinoids is disclosed, biotechnological methods can be employed to produce cannabinoids in heterologous systems. This would pave the way toward biosynthesizing any cannabinoid compound of interest, especially minor substances that are less produced by a plant but have a high medicinal value. In this context, microalgae have attracted increasing scientific interest given their unique potential for biopharmaceutical production. In the present review, the current knowledge on cannabinoid production in different hosts is summarized and the biotechnological potential of microalgae as an emerging platform for synthetic production is put in perspective. A critical survey of genetic requirements and various transformation approaches are also discussed.

Metabolic Engineering and Synthetic Biology Approaches for the Heterologous Production of Aromatic Polyketides

Polyketides are a diverse set of natural products with versatile applications as pharmaceuticals, nutraceuticals, and cosmetics, to name a few. Of several types of polyketides, aromatic polyketides comprising type II and III polyketides contain many chemicals important for human health such as antibiotics and anticancer agents. Most aromatic polyketides are produced from soil bacteria or plants, which are difficult to engineer and grow slowly in industrial settings. To this end, metabolic engineering and synthetic biology have been employed to efficiently engineer heterologous model microorganisms for enhanced production of important aromatic polyketides. In this review, we discuss the recent advancement in metabolic engineering and synthetic biology strategies for the production of type II and type III polyketides in model microorganisms. Future challenges and prospects of aromatic polyketide biosynthesis by synthetic biology and enzyme engineering approaches are also discussed.

Designing artificial pathways for improving chemical production

Metabolic engineering exploits manipulation of catalytic and regulatory elements to improve a specific function of the host cell, often the synthesis of interesting chemicals. Although naturally occurring pathways are significant resources for metabolic engineering, these pathways are frequently inefficient and suffer from a series of inherent drawbacks. Designing artificial pathways in a rational manner provides a promising alternative for chemicals production. However, the entry barrier of designing artificial pathway is relatively high, which requires researchers a comprehensive and deep understanding of physical, chemical and biological principles. On the other hand, the designed artificial pathways frequently suffer from low efficiencies, which impair their further applications in host cells. Here, we illustrate the concept and basic workflow of retrobiosynthesis in designing artificial pathways, as well as the most currently used methods including the knowledge- and computer-based approaches. Then, we discuss how to obtain desired enzymes for novel biochemistries, and how to trim the initially designed artificial pathways for further improving their functionalities. Finally, we summarize the current applications of artificial pathways from feedstocks utilization to various products synthesis, as well as our future perspectives on designing artificial pathways.

Current status and future prospects in cannabinoid production through in vitro culture and synthetic biology

For centuries, cannabis has been a rich source of fibrous, pharmaceutical, and recreational ingredients. Phytocannabinoids are the most important and well-known class of cannabis-derived secondary metabolites and display a broad range of health-promoting and psychoactive effects. The unique characteristics of phytocannabinoids (e.g., metabolite likeness, multi-target spectrum, and safety profile) have resulted in the development and approval of several cannabis-derived drugs. While most work has focused on the two main cannabinoids produced in the plant, over 150 unique cannabinoids have been identified. To meet the rapidly growing phytocannabinoid demand, particularly many of the minor cannabinoids found in low amounts in planta, biotechnology offers promising alternatives for biosynthesis through in vitro culture and heterologous systems. In recent years, the engineered production of phytocannabinoids has been obtained through synthetic biology both in vitro (cell suspension culture and hairy root culture) and heterologous systems. However, there are still several bottlenecks (e.g., the complexity of the cannabinoid biosynthetic pathway and optimizing the bioprocess), hampering biosynthesis and scaling up the biotechnological process. The current study reviews recent advances related to in vitro culture-mediated cannabinoid production. Additionally, an integrated overview of promising conventional approaches to cannabinoid production is presented. Progress toward cannabinoid production in heterologous systems and possible avenues for avoiding autotoxicity are also reviewed and highlighted. Machine learning is then introduced as a powerful tool to model, and optimize bioprocesses related to cannabinoid production. Finally, regulation and manipulation of the cannabinoid biosynthetic pathway using CRISPR- mediated metabolic engineering is discussed.

Profiling Cannabinoid Contents and Expression Levels of Corresponding Biosynthetic Genes in Commercial Cannabis (Cannabis sativa L.) Cultivars

Cannabis (Cannabis sativa L.) is widely cultivated and studied for its psychoactive and medicinal properties. As the major cannabinoids are present in acidic forms in Cannabis plants, non-enzymatic processes, such as decarboxylation, are crucial for their conversion to neutral active cannabinoid forms. Herein, we detected the levels of cannabidivarin (CBDV), cannabidiol (CBD), cannabichromene (CBC), and Δ9-tetrahydrocannabinol (Δ9-THC) in the leaves and vegetative shoots of five commercial Cannabis cultivars using a combination of relatively simple extraction, decarboxylation, and high-performance liquid chromatography analyses. The CBDV, CBC, and Δ9-THC levels were 6.3-114.9, 34.4-187.2, and 57.6-407.4 μg/g, respectively, and the CBD levels were the highest, ranging between 1.2-8.9 μg/g in leaf and vegetative shoot tissues of Cannabis cultivars. Additionally, correlations were observed between cannabinoid accumulation and transcription levels of genes encoding key enzymes for cannabinoid biosynthesis, including CsCBGAS, CsCBDAS, CsCBCAS, and CsTHCAS. These data suggest that the high accumulation of cannabinoids, such as CBC, Δ9-THC, and CBD, might be derived from the transcriptional regulation of CsCBGAS and CsCBDAS in Cannabis plants.

Biosynthesis of cannabinoid precursor olivetolic acid in genetically engineered Yarrowia lipolytica

Engineering microbes to produce plant-derived natural products provides an alternate solution to obtain bioactive products. Here we report a systematic approach to sequentially identify the rate-limiting steps and improve the biosynthesis of the cannabinoid precursor olivetolic acid (OLA) in Yarrowia lipolytica. We find that Pseudomonas sp LvaE encoding a short-chain acyl-CoA synthetase can efficiently convert hexanoic acid to hexanoyl-CoA. The co-expression of the acetyl-CoA carboxylase, the pyruvate dehydrogenase bypass, the NADPH-generating malic enzyme, as well as the activation of peroxisomal β-oxidation pathway and ATP export pathway are effective strategies to redirect carbon flux toward OLA synthesis. Implementation of these strategies led to an 83-fold increase in OLA titer, reaching 9.18 mg/L of OLA in shake flask culture. This work may serve as a baseline for engineering cannabinoids biosynthesis in oleaginous yeast species.

Scale-up of an amoeba-based process for the production of the cannabinoid precursor olivetolic acid

Background

The availability of new biological platform organisms to get access to innovative products and processes is fundamental for the progress in biotechnology and bioeconomy. The amoeba Dictyostelium discoideum represents a novel host system that has recently been employed for both the discovery of new natural products and as a cell factory for the production of bioactive compounds such as phytochemicals. However, an essential parameter to evaluate the potential of a new host system is the demonstration of its scalability to allow industrial applicability. Here, we aimed to develop a bioprocess for the production of olivetolic acid, the main precursor of cannabinoids synthesized by a recently engineered D. discoideum strain.

Results

In this study, a sophisticated approach is described to scale-up an amoeba-based polyketide production process in stirred tank bioreactors. Due to the shear sensitivity of the cell wall lacking amoebae, the maximum local energy dissipation rate (ε_max) was selected as a measure for the hydromechanical stress level among different scales. By performing 1.6-L scale batch fermentations with different stress conditions, we determined a maximum tolerable ε_max of 3.9 W/kg for D. discoideum. Further, we used this parameter as scale-up criterion to develop a bioprocess for olivetolic acid production starting from a 7-L stirred tank reactor to the industrially relevant 300-L scale with a product concentration of 4.8 µg/L, a productivity of 0.04 µg/L/h and a yield of 0.56 µg/g glucose.

Conclusion

We developed a robust and reliable scale-up strategy for amoeba-based bioprocesses and evaluated its applicability for the production of the cannabinoid precursor olivetolic acid. By determining the maximum tolerable hydromechanical stress level for D. discoideum, we were able to scale-up the process from shake flasks to the 300-L stirred tank reactor without any yield reduction from cell shearing. Hence, we showed the scalability and biotechnological exploitation of amoeba-based processes that can provide a reasonable alternative to chemical syntheses or extractions of phytochemicals from plant biomass.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12934-022-01943-w.

Reverse β-oxidation pathways for efficient chemical production

Microbial production of fuels, chemicals, and materials has the potential to reduce greenhouse gas emissions and contribute to a sustainable bioeconomy. While synthetic biology allows readjusting of native metabolic pathways for the synthesis of desired products, often these native pathways do not support maximum efficiency and are affected by complex regulatory mechanisms. A synthetic or engineered pathway that allows modular synthesis of versatile bioproducts with minimal enzyme requirement and regulation while achieving high carbon and energy efficiency could be an alternative solution to address these issues. The reverse β-oxidation (rBOX) pathways enable iterative non-decarboxylative elongation of carbon molecules of varying chain lengths and functional groups with only four core enzymes and no ATP requirement. Here, we describe recent developments in rBOX pathway engineering to produce alcohols and carboxylic acids with diverse functional groups, along with other commercially important molecules such as polyketides. We discuss the application of rBOX beyond the pathway itself by its interfacing with various carbon-utilization pathways and deployment in different organisms, which allows feedstock diversification from sugars to glycerol, carbon dioxide, methane, and other substrates.

Engineering precursor and co-factor supply to enhance D-pantothenic acid production in Bacillus megaterium

High-yielding chemical and chemo-enzymatic methods of D-pantothenic acid (DPA) synthesis are limited by using poisonous chemicals and DL-pantolactone racemic mixture formation. Alternatively, the safe microbial fermentative route of DPA production was found promising but suffered from low productivity and precursor supplementation. In this study, Bacillus megaterium was metabolically engineered to produce DPA without precursor supplementation. In order to provide a higher supply of precursor D-pantoic acid, key genes involved in its synthesis are overexpressed, resulting strain was produced 0.53 ± 0.08 g/L DPA was attained in shake flasks. Cofactor CH2-THF was found to be vital for DPA biosynthesis and was regenerated through the serine-glycine degradation pathway. Enhanced supply of another precursor, β-alanine was achieved by codon optimization and dosing of the limiting L-asparate-1-decarboxylase (ADC). Co-expression of Pantoate-β-alanine ligase, ADC, phosphoenolpyruvate carboxylase, aspartate aminotransferase and aspartate ammonia-lyase enhanced DPA concentration to 2.56 ± 0.05 g/L at shake flasks level. Fed-batch fermentation in a bioreactor with and without the supplementation of β-alanine increased DPA concentration to 19.52 ± 0.26 and 4.78 ± 0.53 g/L, respectively. This present study successfully demonstrated a rational approach combining precursor supply engineering with cofactor regeneration for the enhancement of DPA titer in recombinant B. megaterium.

Engineering the amoeba Dictyostelium discoideum for biosynthesis of a cannabinoid precursor and other polyketides

Aromatic polyketides are natural polyphenolic compounds with a broad spectrum of pharmacological activities. Production of those metabolites in the model organisms Escherichia coli and Saccharomyces cerevisiae has been limited by the extensive cellular engineering needed for the coordinated biosynthesis of polyketides and their precursors. In contrast, the amoeba Dictyostelium discoideum is a native producer of secondary metabolites and harbors a wide, but largely unexplored, repertoire of genes for the biosynthesis of polyketides and terpenoids. Here we present D. discoideum as an advantageous chassis for the production of aromatic polyketides. By expressing its native and cognate plant polyketide synthase genes in D. discoideum, we demonstrate production of phlorocaprophenone, methyl-olivetol, resveratrol and olivetolic acid (OA), which is the central intermediate in the biosynthesis of cannabinoids. To facilitate OA synthesis, we further engineered an amoeba/plant inter-kingdom hybrid enzyme that produced OA from primary metabolites in two enzymatic steps, providing a shortcut in a synthetic cannabinoid pathway using the D. discoideum host system.

High-Titer Production of Olivetolic Acid and Analogs in Engineered Fungal Host Using a Nonplant Biosynthetic Pathway

The microbial synthesis of cannabinoids and related molecules requires access to the intermediate olivetolic acid (OA). Whereas plant enzymes have been explored for E. coli and yeast biosynthesis, moderate yields and shunt product formation are major hurdles. Here, based on the chemical logic to form 2,4-dihydroxybenzoate-containing natural products, we discovered a set of fungal tandem polyketide synthases that can produce OA and the related octanoyl-primed derivative sphaerophorolcarboxylic acid in high titers using the model organism Aspergillus nidulans. This new set of enzymes will enable new synthetic biology strategies to access microbial cannabinoids.

Engineering biosynthetic enzymes for industrial natural product synthesis

Covering: 2000 to 2020 Natural products and their derivatives are commercially important medicines, agrochemicals, flavors, fragrances, and food ingredients. Industrial strategies to produce these structurally complex molecules encompass varied combinations of chemical synthesis, biocatalysis, and extraction from natural sources. Interest in engineering natural product biosynthesis began with the advent of genetic tools for pathway discovery. Genes and strains can now readily be synthesized, mutated, recombined, and sequenced. Enzyme engineering has succeeded commercially due to the development of genetic methods, analytical technologies, and machine learning algorithms. Today, engineered biosynthetic enzymes from organisms spanning the tree of life are used industrially to produce diverse molecules. These biocatalytic processes include single enzymatic steps, multienzyme cascades, and engineered native and heterologous microbial strains. This review will describe how biosynthetic enzymes have been engineered to enable commercial and near-commercial syntheses of natural products and their analogs.

Unconventional high-value products from microalgae: A review

Microalgae have gained significant importance in biotechnology development, providing valuable goods and services in multiple applications. Although there is a rising market for most of these applications, the incorporation and introduction of microalgae into new venues will extend in the near future. These advances are due to the vast biodiversity of microalgal species, recent genetic engineering tools, and culture techniques. There are three main possible approaches for novel algal compounds from: (1) recently isolated yet less known microalgae; (2) selectively stressed conditions; and (3) enzymatically adjusted compounds from conventional molecules. All these approaches can be combined in a specific manner. This review discusses the opportunities, potential and limitations of introducing novel microalgae-based products, and how the recent technologies can be deployed to make these products financially viable. To give an outlook to the future, an analysis of the developments and predicted future market that further enlarge the promise of cultivating microalgae for commercial purposes are considered.

Biosynthesis of Nature-Inspired Unnatural Cannabinoids

Natural products make up a large proportion of medicine available today. Cannabinoids from the plant Cannabis sativa is one unique class of meroterpenoids that have shown a wide range of bioactivities and recently seen significant developments in their status as therapeutic agents for various indications. Their complex chemical structures make it difficult to chemically synthesize them in efficient yields. Synthetic biology has presented a solution to this through metabolic engineering in heterologous hosts. Through genetic manipulation, rare phytocannabinoids that are produced in low yields in the plant can now be synthesized in larger quantities for therapeutic and commercial use. Additionally, an exciting avenue of exploring new chemical spaces is made available as novel derivatized compounds can be produced and investigated for their bioactivities. In this review, we summarized the biosynthetic pathways of phytocannabinoids and synthetic biology efforts in producing them in heterologous hosts. Detailed mechanistic insights are discussed in each part of the pathway in order to explore strategies for creating novel cannabinoids. Lastly, we discussed studies conducted on biological targets such as CB1, CB2 and orphan receptors along with their affinities to these cannabinoid ligands with a view to inform upstream diversification efforts.

Escherichia coli as a platform microbial host for systems metabolic engineering

Bio-based production of industrially important chemicals and materials from non-edible and renewable biomass has become increasingly important to resolve the urgent worldwide issues including climate change. Also, bio-based production, instead of chemical synthesis, of food ingredients and natural products has gained ever increasing interest for health benefits. Systems metabolic engineering allows more efficient development of microbial cell factories capable of sustainable, green, and human-friendly production of diverse chemicals and materials. Escherichia coli is unarguably the most widely employed host strain for the bio-based production of chemicals and materials. In the present paper, we review the tools and strategies employed for systems metabolic engineering of E. coli. Next, representative examples and strategies for the production of chemicals including biofuels, bulk and specialty chemicals, and natural products are discussed, followed by discussion on materials including polyhydroxyalkanoates (PHAs), proteins, and nanomaterials. Lastly, future perspectives and challenges remaining for systems metabolic engineering of E. coli are discussed.

Cannabidiol Discovery and Synthesis-a Target-Oriented Analysis in Drug Production Processes

The current state of evidence and recommendations for cannabidiol (CBD) and its health effects change the legal landscape and aim to destigmatize its phytotherapeutic research. Recently, some countries have included CBD as an antiepileptic product for compassionate use in children with refractory epilepsy. The growing demand for CBD has led to the need for high-purity cannabinoids on the emerging market. The discovery and development of approaches toward CBD synthesis have arisen from the successful extraction of Cannabis plants for cannabinoid fermentation in brewer's yeast. To understand different contributions to the design and enhancement of the synthesis of CBD and its key intermediates, a detailed analysis of the history behind cannabinoid compounds and their optimization is provided herein.

The biosynthesis of the cannabinoids

Cannabis has been integral to Eurasian civilization for millennia, but a century of prohibition has limited investigation. With spreading legalization, science is pivoting to study the pharmacopeia of the cannabinoids, and a thorough understanding of their biosynthesis is required to engineer strains with specific cannabinoid profiles. This review surveys the biosynthesis and biochemistry of cannabinoids. The pathways and the enzymes' mechanisms of action are discussed as is the non-enzymatic decarboxylation of the cannabinoic acids. There are still many gaps in our knowledge about the biosynthesis of the cannabinoids, especially for the minor components, and this review highlights the tools and approaches that will be applied to generate an improved understanding and consequent access to these potentially biomedically-relevant materials.

The Biochemistry of Phytocannabinoids and Metabolic Engineering of Their Production in Heterologous Systems

The medicinal properties of cannabis and the its legal status in several countries and jurisdictions has spurred the massive growth of the cannabis economy around the globe. The value of cannabis stems from its euphoric activity offered by the unique phytocannabinoid tetrahydrocannabinol (THC). However, this is rapidly expanding beyond THC owing to other non-psychoactive phytocannabinoids with new bioactivities that will contribute to their development into clinically useful drugs. The discovery of the biosynthesis of major phytocannabinoids has allowed the exploration of their heterologous production by synthetic biology, which may lead to the industrial production of rare phytocannabinoids or novel synthetic cannabinoid pharmaceuticals that are not easily offered by cannabis plants. This review summarizes the biosynthesis of major phytocannabinoids in detail, the most recent development of their metabolic engineering in various systems, and the engineering approaches and strategies used to increase the yield.

A bio-inspired cell-free system for cannabinoid production from inexpensive inputs

Moving cannabinoid production away from the vagaries of plant extraction and into engineered microbes could provide a consistent, purer, cheaper and environmentally benign source of these important therapeutic molecules, but microbial production faces notable challenges. An alternative to microbes and plants is to remove the complexity of cellular systems by employing enzymatic biosynthesis. Here we design and implement a new cell-free system for cannabinoid production with the following features: (1) only low-cost inputs are needed; (2) only 12 enzymes are employed; (3) the system does not require oxygen and (4) we use a nonnatural enzyme system to reduce ATP requirements that is generally applicable to malonyl-CoA-dependent pathways such as polyketide biosynthesis. The system produces ~0.5 g l-1 cannabigerolic acid (CBGA) or cannabigerovarinic acid (CBGVA) from low-cost inputs, nearly two orders of magnitude higher than yeast-based production. Cell-free systems such as this may provide a new route to reliable cannabinoid production.

Integrative Biosynthetic Gene Cluster Mining to Optimize a Metabolic Pathway to Efficiently Produce l-Homophenylalanine in Escherichia coli

Mining biosynthetic genes for the exploration of hybrid metabolic pathways is a promising approach in heterologous production of natural and unnatural products. Here, we developed an integrative biosynthetic gene cluster (BGC) mining strategy to engineer the biosynthesis of l-homophenylalanine (l-Hph), an important intermediate for the synthesis of angiotensin-converting enzyme inhibitors. We assembled the putative l-Hph BGCs and integrated phylogenetic analysis with target metabolite abundance mapping to prioritize candidate BGCs. To obtain an effective l-Hph pathway, various combinations of candidate genes from different species were screened in an iterative design-build-test stepwise manner. After the pathway was strength balanced and the metabolic flux was enhanced, engineered Escherichia coli produced 1.41 g/L of l-Hph from glucose in feeding shake-flask fermentation. Our cluster mining strategy enabled optimization of the target metabolic pathway, and it would be promising for production of other valuable products in the postgenomic era.

Advances and Prospects of Phenolic Acids Production, Biorefinery and Analysis

Biotechnological production of phenolic acids is attracting increased interest due to their superior antioxidant activity, as well as other antimicrobial, dietary, and health benefits. As secondary metabolites, primarily found in plants and fungi, they are effective free radical scavengers due to the phenolic group available in their structure. Therefore, phenolic acids are widely utilised by pharmaceutical, food, cosmetic, and chemical industries. A demand for phenolic acids is mostly satisfied by utilising chemically synthesised compounds, with only a low quantity obtained from natural sources. As an alternative to chemical synthesis, environmentally friendly bio-based technologies are necessary for development in large-scale production. One of the most promising sustainable technologies is the utilisation of microbial cell factories for biosynthesis of phenolic acids. In this paper, we perform a systematic comparison of the best known natural sources of phenolic acids. The advances and prospects in the development of microbial cell factories for biosynthesis of these bioactive compounds are discussed in more detail. A special consideration is given to the modern production methods and analytics of phenolic acids.

The role of bacterial cell envelope structures in acid stress resistance in E. coli

Acid resistance (AR) is an indispensable mechanism for the survival of neutralophilic bacteria, such as Escherichia coli (E. coli) strains that survive in the gastrointestinal tract. E. coli acid tolerance has been extensively studied during past decades, with most studies focused on gene regulation and mechanisms. However, the role of cell membrane structure in the context of acid stress resistance has not been discussed in depth. Here, we provide a comprehensive review of the roles and mechanisms of the E. coli cell envelope from different membrane components, such as membrane proteins, fatty acids, chaperones, and proton-consuming systems, and particularly focus on the innovative effects revealed by recent studies. We hope that the information guides us to understand the bacterial survival strategies under acid stress and to further explore the AR regulatory mechanisms to prevent or treat E. coli and other related Gram-negative bacteria infection, or to enhance the AR of engineering E. coli.

Structure of the Cannabis sativa olivetol-producing enzyme reveals cyclization plasticity in type III polyketide synthases

In the native pathway to therapeutic cannabinoid biosynthesis in Cannabis sativa, the three‐step production of a key intermediate, olivetolic acid, is catalysed by the enzymes tetraketide synthase (TKS; linear tetraketide intermediate production in two stages) and olivetolic acid cyclase (OAC; final C2 → C7 aldol condensation). In the absence of OAC, a nonenzymatic C2 → C7 decarboxylative aldol condensation of the tetraketide intermediate occurs forming olivetol. TKS is a type III polyketide synthase, and the question arises why it is unable to form olivetolic acid directly, but instead forms this unwanted side product. We determined the TKS, CoA complex structure, and performed structurally guided mutagenesis studies to identify potential residues responsible for cyclization pathway discrimination in type III polyketide synthases. Prior studies suggested an ‘aldol switch’ is necessary to allow linear tetraketide intermediate release prior to cyclization, thereby enabling subsequent olivetolic acid production by OAC. However, our studies do not support the presence of a universal or predictable ‘aldol switch’ consensus sequence. Instead, we propose the mode of ordered active site water activation between type III polyketide synthases catalysing different cyclization mechanisms is subtle and homologue‐specific. Our work indicates that subtle structural variations between homologous enzymes can have a major mechanistic impact on the catalytic outcome. This highlights the importance of embedding high‐resolution structural analysis of multiple enzyme homologues with classical site‐directed mutagenesis studies when investigating highly similar enzymes with different mechanistic pathway outcomes.

Enzymes

TKS, http://www.chem.qmul.ac.uk/iubmb/enzyme/EC2/3/1/206.html; OAC, http://www.chem.qmul.ac.uk/iubmb/enzyme/EC4/4/1/26.html; chalcone synthase, http://www.chem.qmul.ac.uk/iubmb/enzyme/EC2/3/1/74.html; stilbene synthase, http://www.chem.qmul.ac.uk/iubmb/enzyme/EC2/3/1/95.html; 2‐PS, http://www.chem.qmul.ac.uk/iubmb/enzyme/EC2/3/1/-.html.

Accession numbers

The atomic coordinates and structure factors for the crystal structure of TKS have been deposited in the Protein Data Bank with accession number http://www.rcsb.org/pdb/search/structidSearch.do?structureId=6GW3.

Computer-aided re-engineering of nonribosomal peptide and polyketide biosynthetic assembly lines

Covering: 2014 to 2019Nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs) have been the subject of engineering efforts for multiple decades. Their modular assembly line architecture potentially allows unlocking vast chemical space for biosynthesis. However, attempts thus far are often met with mixed success, due to limited molecular compatibility of the parts used for engineering. Now, new engineering strategies, increases in genomic data, and improved computational tools provide more opportunities for major progress. In this review we highlight some of the challenges and progressive strategies for the re-design of NRPSs & type I PKSs and survey useful computational tools and approaches to attain the ultimate goal of semi-automated and design-based engineering of novel peptide and polyketide products.

Direct Aromatic Nitration System for Synthesis of Nitrotryptophans in Escherichia coli

Nitrotryptophan and its analogues are useful building blocks for synthesizing bioactive and biotechnologically relevant chemicals, materials, and proteins. However, synthetic routes to enantiopure nitro-containing tryptophan derivatives are either complex and polluting or even unestablished yet. Herein, we describe microbial production of 4-NO₂-l-tryptophan (Nitrotrp) and its analogues by designing and expressing the biosynthetic pathway in Escherichia coli. The biosynthetic pathway comprised one engineered self-sufficient P450 TB14 of Streptomyces origin for direct nitration of the C-4 of l-Trp indole and one nitric oxide synthase from Bacillus subtilis (BsNOS) for the production of nitric oxide (NO) from l-Arg to support the direct aromatic nitration. As both TB14 and BsNOS require reducing agent NADPH for their reactions, we also included one glucose dehydrogenase (GDH) from B. subtilis for in situ NADPH regeneration. The initially designed pathway led to 16.2 ± 2.3 mg/L of Nitrotrp by the engineered E. coli fermented in the M9 minimal medium for 3 days. A combination of the design and screening of three additional pathways, fermentation optimization and the knockout of competitive metabolic pathways together improved the Nitrotrp titer to around 192 mg/L within 20 h. Finally, the whole-cell biotransformation system produced eight Nitrotrp analogues with their titers varying from 2.5 to 61.5 mg/L. This work provides the first microbial direct aromatic nitration processes and sets the stage for the development of biocatalytic routes to other useful nitroaromatics in the future.

A cell-free platform for the prenylation of natural products and application to cannabinoid production

Prenylation of natural compounds adds structural diversity, alters biological activity, and enhances therapeutic potential. Because prenylated compounds often have a low natural abundance, alternative production methods are needed. Metabolic engineering enables natural product biosynthesis from inexpensive biomass, but is limited by the complexity of secondary metabolite pathways, intermediate and product toxicities, and substrate accessibility. Alternatively, enzyme catalyzed prenyl transfer provides excellent regio- and stereo-specificity, but requires expensive isoprenyl pyrophosphate substrates. Here we develop a flexible cell-free enzymatic prenylating system that generates isoprenyl pyrophosphate substrates from glucose to prenylate an array of natural products. The system provides an efficient route to cannabinoid precursors cannabigerolic acid (CBGA) and cannabigerovarinic acid (CBGVA) at >1 g/L, and a single enzymatic step converts the precursors into cannabidiolic acid (CBDA) and cannabidivarinic acid (CBDVA). Cell-free methods may provide a powerful alternative to metabolic engineering for chemicals that are hard to produce in living organisms.

Producing individual cannabinoids by metabolically engineered microbes has proven challenging. Here, the authors develop a cell-free enzymatic prenylating system to generate isoprenyl pyrophosphate substrates directly from glucose and produce both common and rare cannabinoids at >1 g/L.

Engineering Escherichia coli as a platform for the in vivo synthesis of prenylated aromatics

Prenylated aromatics (PAs) are an important class of natural products with valuable pharmaceutical applications. To address current limitations of their sourcing from plants, here, we present a microbial platform for the in vivo synthesis of PAs based on the aromatic prenyltransferase NphB from Streptomyces sp. strain CL190. As proof of concept, we targeted the prenylation of phenolic/phenolcarboxylic acids, including orsellinic (OSA), divarinolic (DVA), and olivetolic (OLA) acids, whose prenylated products have important biopharmaceutical applications. Although the ability of wild-type NphB to catalyze the prenylation reaction with each acid was validated by in vitro characterization, improvement of product titers in vivo required protein modeling and rational design to engineer NphB variants with increased activity and product selectivity. When a designed NphB variant with eightfold improved catalytic efficiency toward OSA was expressed in an Escherichia coli host engineered to generate geranyl pyrophosphate at high flux through the mevalonate pathway, we observed up to 300 mg/L prenylated products by exogenously supplying OSA. The improved properties of engineered NphB were also utilized to demonstrate the diversification of this in vivo platform by using both different aromatic acceptors and different prenyl donors to generate various PA compounds, including medicinally important compounds such as cannabigerovarinic, cannabigerolic, and grifolic acids.