Novel method utilizing microbial treatment for cleaner production of diosgenin from Dioscorea zingiberensis C.H. Wright (DZW)

Microbial metabolism of diosgenin by a novel isolated Mycolicibacterium sp. HK-90: A promising biosynthetic platform to produce 19-carbon and 21-carbon steroids

Green manufacture of steroid precursors from diosgenin by microbial replacing multistep chemical synthesis has been elusive. It is currently limited by the lack of strain and degradation mechanisms. Here, we demonstrated the feasibility of this process using a novel strain Mycolicibacterium sp. HK-90 with efficiency in diosgenin degradation. Diosgenin degradation by strain HK-90 involves the selective removal of 5,6-spiroketal structure, followed by the oxygenolytic cleavage of steroid nuclei. Bioinformatic analyses revealed the presence of two complete steroid catabolic gene clusters, SCG-1 and SCG-2, in the genome of strain HK-90. SCG-1 cluster was found to be involved in classic phytosterols or cholesterol catabolic pathway through the deletion of key kstD1 gene, which promoted the mutant m-∆kstD1 converting phytosterols to intermediate 9α-hydroxyandrostenedione (9-OHAD). Most impressively, global transcriptomics and characterization of key genes suggested SCG-2 as a potential gene cluster encoding diosgenin degradation. The gene inactivation of kstD2 in SCG-2 resulted in the conversion of diosgenin to 9-OHAD and 9,16-dihydroxy-pregn-4-ene-3,20-dione (9,16-(OH)2 -PG) in mutant m-ΔkstD2. Moreover, the engineered strain mHust-ΔkstD1,2,3 with a triple deletion of kstDs was constructed, which can stably accumulate 9-OHAD by metabolizing phytosterols, and accumulate 9-OHAD and 9,16-(OH)2 -PG from diosgenin. Diosgenin catabolism in strain mHust-ΔkstD1,2,3 was revealed as a progression through diosgenone, 9,16-(OH)2 -PG, and 9-OHAD to 9α-hydroxytestosterone (9-OHTS). So far, this work is the first report on genetically engineered strain metabolizing diosgenin to produce 21-carbon and 19-carbon steroids. This study presents a promising biosynthetic platform for the green production of steroid precursors, and provide insights into the complex biochemical mechanism of diosgenin catabolism.

The Isolation, Identification and Immobilization Method of Three Novel Enzymes with Diosgenin-Producing Activity Derived from an Aspergillus flavus

Diosgenin is an important raw material used in the synthesis of steroid drugs, and it is widely used in the pharmaceutical industry. The traditional method of producing diosgenin is through using raw materials provided via the plant Dioscorea zingiberensis C. H. Wright (DZW), which is subsequently industrially hydrolyzed using a high quantity of hydrochloric and sulfuric acids at temperatures ranging from 70 °C to 175 °C. This process results in a significant amount of unmanageable wastewater, creates issues of severe environmental pollution and consumes high quantities of energy. As an alternative, the enzymolysis of DZW to produce diosgenin is an environmentally and friendly method with wide-ranging prospects for its application. However, there are still only a few enzymes that are suitable for production on an industrial scale. In this study, three new key enzymes, E1, E2, and E3, with a high conversion stability of diosgenin, were isolated and identified using an enzyme-linked-substrate autography strategy. HPLC-MS/MS identification showed that E1, a 134.45 kDa protein with 1019 amino acids (AAs), is a zinc-dependent protein similar to the M16 family. E2, a 97.89 kDa protein with 910 AAs, is a type of endo-β-1,3-glucanase. E3, a 51.6 kDa protein with 476 AAs, is a type of Xaa-Pro aminopeptidase. In addition, the method to immobilize these proteins was optimized, and stability was achieved. The results show that the optimal immobilization parameters are 3.5% sodium alginate, 3.45% calcium chloride concentration, 1.4 h fixed time, and pH 8.8; and the recovery rate of enzyme activity can reach 43.98%. A level of 70.3% relative enzyme activity can be obtained after employing six cycles of the optimized technology. Compared with free enzymes, immobilized enzymes have improved stability, acid and alkaline resistance and reusability, which are conducive to large-scale industrial production.

Research progress of diosgenin extraction from Dioscorea zingiberensis C. H. Wright: Inspiration of novel method with environmental protection and efficient characteristics

Diosgenin was the starting materials to synthesize various hormone drugs and mainly generated from Dioscorea zingiberensis C. H. Wright by acidolysis, enzymolysis, microbiological fermentation, and integrated manner. Only acidic hydrolysis with strong acid such as hydrochloric acid or sulfuric acid was used in practice in diosgenin enterprises due to their feasibility and simplicity, nevertheless finally resulting in a great deal of unmanageable wastewater and severely polluted the surrounding environment. Aiming to provide a comprehensive and up-to date information of researches on diosgenin production from this plant, 151 cases were collected from scientific databases including Web of Science, Pubmed, Science Direct, Wiley, Springer, and China Knowledge Resource Integrated (CNKI). Their advantages and disadvantages with different production methods were analyzed based on these available data in this review paper. Considering the fact that nearly all of diosgenin enterprises were closed for the environmental protection and the life health of the people, this review paper was beneficial for providing useful guidelines to develop novel technologies with environmentally-friendly and cleaner features for diosgenin production or facilitate the transformation of other methods like enzymolysis, microbiological fermentation, or integrated methods from laboratory scale to industry scale.

Identification and a phased pH control strategy of diosgenin bio-synthesized by an endogenous Bacillus licheniformis Syt1 derived from Dioscorea zingiberensis C. H. Wright

Diosgenin is widely used as one precursor of steroidal drugs in pharmaceutical industry. Currently, there is no choice but to traditionally extract diosgenin from Dioscorea zingiberensis C. H. Wright (DZW) or other plants. In this work, an environmentally friendly approach, in which diosgenin can be bio-synthesized by the endophytic bacterium Bacillus licheniformis Syt1 isolated from DZW, is proposed. Diosgenin produced by the strain was identified by high-performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR), and Fourier transform infrared spectroscopy (FTIR). The thermal gravimetric analysis (TGA) showed that the melting point of the diosgenin product was 204 °C. The optical rotation measurement exhibited that the optical rotation was α²⁰₅₈₉ =  - 126.1° ± 1.5° (chloroform, c = 1%): negative sign means that the product is left-handed, which is very important to further produce steroid hormone drugs. Cholesterol may be the intermediate product in the diosgenin biosynthesis pathway. In the batch fermentation process to produce diosgenin using the strain, pH values played an important role. A phased pH control strategy from 5.5 to 7.5 was proved to be more effective to improve production yield than any single pH control, which could get the highest diosgenin yield of 85 ± 8.6 mg L^-1. The proposed method may replace phyto-chemistry extraction to produce diosgenin in the industry in the future.Key points• An endophytic Bacillus licheniformis Syt1 derived from host can produce diosgenin.• A dynamic pH industrial control strategy is better than any single pH control.• Proposed diosgenin-produced method hopefully replaces phyto-chemistry extraction.

Advances in steroidal saponins biosynthesis

This work reviews recent advances in the pathways and key enzymes of steroidal saponins biosynthesis and sets the foundation for the biotechnological production of these useful compounds through transformation of microorganisms. Steroidal saponins, due to their specific chemical structures and active effects, have long been important natural products and that are irreplaceable in hormone production and other pharmaceutical industries. This article comprehensively reviewed the previous and current research progress and summarized the biosynthesis pathways and key biosynthetic enzymes of steroidal saponins that have been discovered in plants and microoganisms. On the basis of the general biosynthetic pathway in plants, it was found that the starting components, intermediates and catalysing enzymes were diverse between plants and microorganisms; however, the functions of their related enzymes tended to be similar. The biosynthesis pathways of steroidal saponins in microorganisms and marine organisms have not been revealed as clearly as those in plants and need further investigation. The elucidation of biosynthetic pathways and key enzymes is essential for understanding the synthetic mechanisms of these compounds and provides researchers with important information to further develop and implement the massive production of steroidal saponins by biotechnological approaches and methodologies.

Diosgenin and galactomannans, natural products in the pharmaceutical sciences

Background

Diosgenin is an isospirostane derivative, which is a steroidal sapogenin and the product of acids or enzymes hydrolysis process of dioscin and protodioscin. Galactomannans are heteropolysaccharides composed of D-mannose and D-galactose, which are major sources of locust bean, guar, tara and fenugreek.

Methods

Literature survey was accomplished using multiple databases including PubMed, Science Direct, ISI web of knowledge and Google Scholar.

Results

Four major sources of seed galactomannans are locust bean (Ceratonia siliqua), guar (Cyamopsis tetragonoloba), tara (Caesalpinia spinosa Kuntze), and fenugreek (T.foenum-graecum). Diosgenin has effect on immune system, lipid system, inflammatory and reproductive systems, caner, metabolic process, blood system, blood glucose and calcium regulation. The most important pharmacological benefits of galactomannan are antidiabetic, antioxidant, anticancer, anticholinesterase, antiviral activities, and appropriate for dengue virus and gastric diseases.

Conclusions

Considering the importance of diosgenin and galactomannans, the obtained findings suggest potential of diosgenin and galactomannans as natural products in pharmaceutical industries.

Influence of Soil Variation on Diosgenin Content Profile in Costus speciosus from Indo-Gangetic Plains

Costus speciosus is a rich source of commercially important compound Diosgenin, distributed in different regions of India. The present investigation was aimed to quantify diosgenin through High Performance Thin Layer Chromatography in 34 germplasms of Costus speciosus and also to identify the superior sources and to correlate the macronutrients of rhizospheric soil. The starch content varied in microscopic examination and correlated inversely (r=-0.266) with diosgenin content. Findings revealed that the extraction process with acid hydrolysis yielded higher diosgenin content (0.15-1.88 %) as compared to non-hydrolysis (0.009-0.368 %) procedure. Germplasms from Uttar Pradesh (NBCS-4), Jharkhand (NBCS-39) and Bihar (NBCS-2) were identified as elite chemotypes based on hierarchical clustering analysis. The phosphorous content of respective rhizospheric soil correlated positively (r=0.742) with diosgenin content. Findings of present study are useful to identify the new agrotechniques. The elite germplasms can also be used as quality planting material for large scale cultivation in order to assure a sustained supply to the herbal drug industry.

Comparative study of the adsorption/immobilization of Cu by turmeric residues after microbial and chemical extraction

The turmeric industry produces a huge amount of residues annually. After undergoing different extraction process, turmeric residue biomass may be transformed from waste to resource. Turmeric residues exhibit different characteristics suitable for various environmental applications. In this work, the adsorption of Cu(II) onto turmeric residues from microbial (TR-A) and chemical (TR-B) extraction was investigated. The characteristics of the residues were examined via Brunauer-Emmett-Teller analysis, thermogravimetric analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy, and elemental analysis. Then, applications to Cu(II) immobilization were identified. Results suggested that although TR-B had better thermal stability, larger surface area, and more pores than TR-A, the adsorption capacity of Cu(II) onto TR-A was higher (13.12 mg/g) than that onto TR-B (7.37 mg/g) because TR-A had more microbial cell debris, metabolites, and S element than TR-B. In practice, TR-A-added soil achieved 40% more Cu immobilization than TR-B-added soil under continuous leaching of simulated acid rain. Consequently, the residues extracted using the microbial method prevented pollution after the traditional extraction process and transformed waste into a material for environmental remediation.

Eco-friendly microbial production of diosgenin from saponins in Dioscorea zingiberensis tubers in the presence of Aspergillus awamori

A novel microbial procedure was proposed for diosgenin production from Dioscorea zingiberensis C.H. Wright (DZW) tubers via employing Aspergillus awamori for the first time. The optimal conditions of fermenter cultivation were established as inoculation dosage of 8%, fermentation temperature of 30 °C, cultivation time of 8 days, initial pH of 7.0 and a stirring rate of 180 rpm when the converted diosgenin content reached a peak value of 74.26 ± 3.23 mg/g substrate. The product was purified by silica gel column and then confirmed as diosgenin (purity: 96.9 ± 2.42%) by nuclear magnetic resonance (NMR). Compared with traditional acid hydrolysis, this new process generated indeed less wastewater with lower chemical oxygen demand (COD) reduced to 500 mg/L from 10,000 mg/L and absence of acid and alkali. This research provided definitely an environmental and high-efficiency microbial technology for diosgenin production.

Isolation of endophytic fungi from Dioscorea zingiberensis C. H. Wright and application for diosgenin production by solid-state fermentation

In this study, endophytic fungi were isolated from Dioscorea zingiberensis C.H. Wright (DZW), and a novel clean process to prepare diosgenin from DZW was developed. A total of 123 strains of endophytic fungi were isolated from different plant tissues of DZW. Among them, the strain Fusarium sp. (CPCC 400709) showed the best activity of hydrolyzing steroidal saponins in DZW into diosgenin. Thus, this strain was used to prepare diosgenin from DZW by solid-state fermentation. The fermentation parameters were optimized using response surface methodology, and a high yield of diosgenin (2.16%) was obtained at 14.5% ammonium sulfate, an inoculum size of 12.3%, and 22 days of fermentation. Furthermore, the highest diosgenin yield (2.79%) was obtained by co-fermentation with Fusarium sp. (CPCC 400709) and Curvularia lunata (CPCC 400737), which was 98.9% of that obtained by β-glucosidase pretreated acid hydrolysis (2.82%). This process is acid-free and wastewater-free, and shows promise as an effective and clean way to prepare diosgenin for use in industrial applications from DZW.

A novel glycosylated solution from Dioscorea zingiberensis C.H. Wright significantly improves the solvent productivity of Clostridium beijerinckii

The economics of bio-solvent production are largely dependent on the cost of the fermentation substrate. Dioscorea zingiberensis C.H. Wright (DZW), the main raw material used to produce saponin, contains 13-18% starch which can be directly saccharified to a saccharification liquid of DZW starch (SLDS) that contains abundant nutrients. In this study, the water-soluble micromolecule compounds in SLDS were quantified through ¹H NMR. Using SLDS as the substrate to conduct ABE fermentation by Clostridium beijerinckii, the fermentation cycle was shortened 24h, the maximum biomass and consumption rate of the glucose significantly increased, and the productivity of total solvents were increased by 0.244±0.010g/L/h compared to standard P₂ medium. Expression analysis of genes encoding key enzymes involved in acetone and butanol production and glucose consumption showed that they were induced by SLDS. Taken together, SLDS is a useful and renewable glycosylated solution for ABE fermentation.

Low pressure steam expansion pretreatment as a competitive approach to improve diosgenin yield and the production of fermentable sugar from Dioscorea zingiberensis C.H. Wright

Development of efficient pretreatment methods which can disrupt the peripheral lignocellulose and even the parenchyma cells is of great importance for production of diosgenin from turmeric rhizomes. It was found that low pressure steam expansion pretreatment (LSEP) could improve the diosgenin yield by more than 40% compared with the case without pretreatment, while simultaneously increasing the production of fermentable sugar by 27.37%. Furthermore, little inhibitory compounds were produced in LSEP process which was extremely favorable for the subsequent biotransformation of fermentable sugar to other valuable products such as ethanol. Preliminary study showed that the ethanol yield when using the fermentable sugar as carbon source was comparable to that using glucose. The liquid residue of LSEP treated turmeric tuber after diosgenin production can be utilized as a quality fermentable carbon source. Therefore, LSEP has great potential in industrial application in diosgenin clean production and comprehensive utilization of turmeric tuber.

In situ high-valued utilization and transformation of sugars from Dioscorea zingiberensis C.H. Wright for clean production of diosgenin

The industrial production of diosgenin in China generates a large amount of high-sugar wastes with low bioavailability, which causes serious pollution to the environment. In this study, a new clean and efficient process for the production of diosgenin was developed using sugars through in situ high-valued transformation. The sugar mixture from Dioscorea zingiberensis C.H. Wright contained abundant beneficial components. Nine typical microorganisms that produced intracellular products were evaluated. Saccharopolyspora spinosa was selected for recursive protoplast fusion to increase the spinosad yield by 46.3% compared with that of the wildtype. Diosgenin and spinosad co-production was conducted in a 100L bioreactor, with pH controlled by adding glucose. The biological oxygen demand of the effluent water decreased from 15,000mg/L to 450mg/L; hence, the proposed process is environment friendly.

Conversion of furostanol saponins into spirostanol saponins improves the yield of diosgenin from Dioscorea zingiberensis by acid hydrolysis

Conversion of furostanol saponins into spirostanol saponins avoiding the side product increases the diosgenin yield in acid hydrolysis of Dioscorea zingiberensis.

Biotransformation of steroidal saponins in sisal (Agave sisalana Perrine) to tigogenin by a newly isolated strain from a karst area of Guilin, China

A rod-shaped bacterium was isolated from the soil in a karst area of Guilin, China and its biotransformation of steroidal saponins in sisal (Agave sisalana Perrine) to tigogenin was presented for the first time. A total of 22 strains for the degradation of steroidal saponins in sisal were isolated from 48 soil samples, and the isolated rod-shaped, bacterial strain ZG-21 was used for the production of tigogenin due to its highest degradation efficiency of steroidal saponins in sisal. The parameters affecting biotransformation by strain ZG-21 were optimized. Under the optimized conditions of temperature (30 °C), pH (6), time (5 days) and substrate concentration (5 mg/mL), a maximum tigogenin yield of 26.7 mg/g was achieved. Compared with the conventional method of acid hydrolysis, the biotransformation method provided a clean and eco-friendly alternative for the production of tigogenin.

Direct Biotransformation of Dioscin into Diosgenin in Rhizome of Dioscorea zingiberensis by Penicillium dioscin

Diosgenin is an important precursor for synthesis of more than 200 steroidal hormone medicines. Rhizome of Dioscorea zingiberensis C. H. Wright (RDZ) contained the highest content of diosgenin in Dioscorea plant species. Diosgenin is traditionally extracted by acid hydrolysis from RDZ. However, the acid hydrolysis process produces massive wastewater which caused serious environment pollution. In this study, diosgenin extraction by direct biotransformation with Penicillium dioscin was investigated. The spawn cultivation conditions were optimized as: Czapeks liquid culture medium without sugar and agar (1,000 ml) + 6.0 g dioscin/6.0 g DL, 30 °C, 36 h; solid fermentation of RDZ: mycelia/RDZ of 0.05 g/kg, 30 °C, 50 h; the yield of diosgenin was over 90 %. Spawn cultivation was crucial for the direct biotransformation. In the spawn cultivation, amount and ratio of dioscin/DL were the key factors to promote biotransformation activity of P. dioscin. This biotransformation method was environment-friendly, simple and energy saving, and might be a potential substitute for acid hydrolysis in diosgenin extraction industry.