As a naturally occurring steroid sapogenin, diosgenin acts as the precursor of hundreds of steroid medicines, and thereby has important medicinal value. Currently, industrial production of diosgenin relies primarily on chemical extraction from plant materials. Clearly, this strategy shows drawbacks of excessive reliance on plant materials and farmland as well as environment pollution. Due to development of metabolic engineering and synthetic biology, bio-production of diosgenin has garnered plenty of attention. Although the biosynthetic pathways of diosgenin have not been completely identified, in this review, we outline the identified biosynthetic pathways and key enzymes. In particular, we suggest heterologous biosynthesis of diosgenin in Saccharomyces cerevisiae. Overall, this review aims to provide valuable insights for future complete biosynthesis of diosgenin.
Biosynthetic Pathways/genetics* ; Diosgenin ; Metabolic Engineering

Unnatural amino acids are widely used in medicine, pesticide, material, and other industries and the green and efficient synthesis has attracted a lot of attention. In recent years, with the rapid development of synthetic biology, microbial cell factories have become a promising means for biosynthesis of unnatural amino acids. This study reviewed the construction and application of microbial cell factories for unnatural amino acid, including the synthetic pathway reconstruction, design/modification of key enzymes and their coordinated regulation with precursors, blocking of competitive alternative pathways, and construction of cofactor circulation systems. Meanwhile, on the basis of the new principles for designing the microbial cell factories, new biosynthetic pathways adapted to cells and the production environment, as well as new biomanufacturing system established based on cell adaptive evolution and intelligent fermentation regulation, we looked forward to the further construction and application of microbial cell factories for industrial bio-production.
Amino Acids/genetics* ; Biosynthetic Pathways ; Fermentation ; Metabolic Engineering ; Synthetic Biology

Natural products, important sources of innovative drugs, food, spices and daily chemicals, are closely related to people's healthy life. With the development and integration of modern biological and chemical technologies of natural products, the researches on biosynthesis of natural products have made great progresses in recent years. The biosynthetic pathways of a number of natural products have been analyzed. Many pathway enzymes and modifying enzymes involved in the biosynthesis of natural products have been mined and functionally characterized. Furthermore, genes encoding pathway enzymes have been introduced into chassis to construct cell factories producing natural products through synthetic biology technologies. Also, other biotechnologies including genome editing and genome mining, have been used in the biosynthesis of natural products. In order to further promote the development of researches on biosynthesis of natural products, we edited a Special Issue on the topic of "biosynthesis of natural products", focusing on the researches progress in three aspects: the analysis of biosynthetic pathways of natural products, genome-wide mining and functional characterization of genes encoding tool enzymes, and the scale preparation of natural products by biosynthetic technology. Also included in this Special Issue was the prospect of the biosynthesis of natural products. This Special Issue can provide reference and guidance for the further development of natural product biosynthesis.
Biological Products ; Biosynthetic Pathways/genetics* ; Biotechnology ; Genome ; Synthetic Biology

Plant polyphenols are phenylpropanoid derivatives including phenolic acids, stilbenes, curcumins and flavonoids. These compounds display a variety of biological and pharmacological activities such as antioxidation, vasorelaxation, anti-coagulation, anti-inflammation, anti-tumor and anti-virus, conferring a huge application potential in the sectors of drugs, foods, cosmetics, and chemicals. Microorganisms have become important hosts for heterologous synthesis of natural products due to the advantages of fast growth, easiness of culture and industrial operation. In recent years, the development of synthetic biology has boosted the microbial synthesis of plant natural products, achieving substantial progress. In this review, we summarize the synthesis of plant polyphenols in engineered Escherichia coli, Saccharomyces cerevisiae and other microorganisms equipped with the designed biosynthetic pathways of polyphenols. We also discuss the optimization strategies such as precursor engineering, dynamic regulation, and co-cultivation to improve the production of polyphenols and propose future prospects for polyphenol pathway engineering.
Biosynthetic Pathways ; Metabolic Engineering ; Plants ; Polyphenols ; Saccharomyces cerevisiae/genetics*

Terpenoids are a group of structurally diverse compounds with good biological activities and versatile functions such as anti-cancer and immunity-enhancing effects, and are widely used in food, healthcare and medical industries. Facilitated by the increasing understandings on the natural biosynthetic pathways of terpenoids in recent years, Saccharomyces cerevisiae has been engineered into high-yield strains for production of a variety of terpenoids, some of which have reached or become close to the level required by industrial production. In this connection, synthetic biology driven biotechnological production of terpenoids has become a promising alternative to chemical synthesis and traditional extraction approaches. This article summarizes the recent process in engineering S. cerevisiae for terpenoids biosynthesis, highlighting the effect of synthetic biology strategies by taking a couple of typical terpenoids as examples.
Biosynthetic Pathways ; Metabolic Engineering ; Saccharomyces cerevisiae/genetics* ; Synthetic Biology ; Terpenes

The effects of water regulation on the biosynthesis of calycosin-7-O-β-D-glucoside in 2-year-old Astragalus membranaceus var. mongholicus were studied,and the mechanism was explained from the aspects of key enzyme gene expression and antioxidant enzyme system. The content of calycosin-7-O-β-D-glucoside was determined by HPLC,and the expression levels of six key enzyme genes( PAL,4 CL,CHS,CHI,IFS,13'H) in the synthesis pathway were analyzed by q RT-PCR. The activities of protective enzymes and contents of osmoregulation substances and malondialdehyde were also determined. In the water deficit group,the maximum concentration of calycosin-7-O-β-D-glucoside was 0. 49 mg·g-1 on the 24 th day of treatment. In the whole water regulation,the water deficit group outweighed the water adequate group in osmoregulation substance and MDA contents. The activities of A. membranaceus var.mongholicus antioxidant enzymes SOD,POD,and CAT increased during the initial period of water regulation,but decreased with time.The expression of PAL,CHS,and 13'H in the water deficit group was at a low level,and the 4 CL had active expression,slightly lower than that in the water adequate group. The expression of CHI and IFS elevated rapidly when water deficit occurred. Correlation analysis showed that the content of calycosin-7-O-β-D-glucoside was positively correlated with CHI expression( P<0. 01) and IFS expression( P<0. 05). Therefore,water regulation can change the accumulation pattern of calycosin-7-O-β-D-glucoside,and water deficit may be an effective way to increase its content. CHI and IFS are the key genes in response to water deficit.
Astragalus propinquus/genetics* ; Biosynthetic Pathways ; Glucosides ; Isoflavones ; Water

The Solanaceae plants distributed in China belong to 105 species and 35 varietas of 24 genera. Some medicinal plants of Solanaceae are rich in tropane alkaloids(TAs), which have significant pharmacological activities. In this paper, the geographical distribution, chemical components, traditional therapeutic effect, pharmacological activities, and biosynthetic pathways of TAs in Solanaceous plants were summarized. Besides, the phylogeny of medicinal plants belonging to Solanaceae was visualized by network diagram. Fourteen genera of Solanaceae plants in China contain TAs and have medical records. TAs mainly exist in Datura, Anisodus, Atropa, Physochlaina, and Hyoscyamus. The TAs-containing species were mainly concentrated in Southwest China, and the content of TAs was closely related to plant distribution area and altitude. The Solanaceae plants containing TAs mainly have antispasmodic, analgesic, antiasthmatic, and antitussive effects. Modern pharmacological studies have proved the central sedative, pupil dilating, glandular secretion-inhibiting, and anti-asthma activities of TAs. These pharmacological activities provide a reasonable explanation for the traditional therapeutic efficacy of tropane drugs. In this paper, the geographical distribution, chemical components, traditional therapeutic effect, and modern pharmacological activities of TAs-containing species in Solanaceae were analyzed for the first time. Based on these data, the genetic relationship of TAs-containing Solanaceae species was preliminarily discussed, which provided a scientific basis for the basic research on TAs-containing solanaceous species and was of great significance for the development of natural medicinal plant resources containing TAs.
Biosynthetic Pathways ; Phylogeny ; Plants, Medicinal ; Solanaceae/genetics* ; Tropanes

Curcuminoids are rare diketone compounds in plants and can be found in the rhizome of Curcuma longa as well as other Zingiberaceae and Araceae. Curcuminoids have been widely used in food and medical area owing to the yellow colors, as well as the antioxidant and many other pharmacological activities. Curcuminoids are a mixture of compounds containing curcumin, demethoxycurcumin and bisdemethoxycurcumin, which have distinct benzene ring substituents. Currently, curcuminoids are exclusively produced through plant extraction, which do not satisfy the meeting of the market demand. Empowered with new synthetic biology tools and metabolic engineering strategies, there is renewed interest in production of curcuminoids using microorganisms. Heterologous production of curcuminoids has been achieved using Escherichia coli, Yarrowia lipolytica, Pseudomonas putida and Aspergillus oryzae via engineering of curcuminoids biosynthesis pathway. In this review, we first describe the biological activities and various applications of curcuminoids. Next, we summarize the biosynthetic pathway of curcuminoids in Curcuma longa and discuss the catalytic mechanisms of curcumin synthases. Then, we thoroughly explore recent advances in the use of distinct microorganisms for the production of curcuminoids with a special focus on metabolic engineering strategies. Finally, we prospect the microbial production of curcuminoids by highlighting some promising techniques and approaches.
Antioxidants ; Biosynthetic Pathways/genetics* ; Curcumin ; Diarylheptanoids ; Metabolic Engineering ; Plant Extracts

It is among the goals in metabolic engineering to construct microbial cell factories producing high-yield and high value-added target products, and an important solution is to design efficient synthetic pathway for the target products. However, due to the difference in metabolic capacity among microbial chassises, the available substrate and the yielded products are limited. Therefore, it is urgent to design related metabolic pathways to improve the production capacity. Existing metabolic engineering approaches to designing heterologous pathways are mainly based on biological experience, which are inefficient. Moreover, the yielded results are in no way comprehensive. However, systems biology provides new methods for heterologous pathway design, particularly the graph-based and constraint-based methods. Based on the databases containing rich metabolism information, they search for and uncover possible metabolic pathways with designated strategy (graph-based method) or algorithm (constraint-based method) and then screen out the optimal pathway to guide the modification of strains. In this paper, we reviewed the databases and algorithms for pathway design, and the applications in metabolic engineering and discussed the strengths and weaknesses of existing algorithms in practical application, hoping to provide a reference for the selection of optimal methods for the design of product synthesis pathway.
Algorithms ; Biosynthetic Pathways ; Metabolic Engineering ; Metabolic Networks and Pathways/genetics* ; Systems Biology

The relationship between saponin content of in different parts of the organization and expression of ginsenoside biosynthesis related gene was obtained by the correlation analysis between saponin content and gene expression. The 14 tissue parts of were studied, six saponins in Samples (ginsenoside Rg₁, Re, Rb₁, Rc, Rb₂ and Rd), group saponins and total saponins were determined by high performance liquid chromatography and vanillin-sulfuric acid colorimetric method. Simultaneously, the expression levels of 7 ginsenoside biosynthesis related genes ( and ) in different tissues of were determined by Real-time fluorescence quantitative PCR. Although 7 kinds of ginsenoside biosynthesis related enzyme gene in the involved in ginsenoside synthesis, the expression of and P450 genes had no significant effect on the content of monosodium saponins, grouping saponins and total saponins, and had significant or extremely significant on the contents of single saponins Re, Rg1, Rb1, Rd, group saponin PPD and PPT, total saponin TMS and total saponin TS (<0.05 or <0.01). The biosynthesis of partial saponins, grouping saponins and total saponins in was affected by the interaction of multiple enzyme genes in the saponin synthesis pathway, the content of saponins in different tissues of was determined by the differences in the expression of key enzymes in the biosynthetic pathway. Therefore, this study further clarified that and was the key enzyme to control the synthesis of saponins in by correlation analysis, the biosynthesis of ginsenosides in was regulated by these five kind of enzymes in cluster co-expression of interaction mode.
Biosynthetic Pathways ; Chromatography, High Pressure Liquid ; Ginsenosides ; biosynthesis ; genetics ; Panax ; genetics ; Plant Roots ; Saponins ; biosynthesis ; genetics