Effects of inoculum size and age on biomass growth and paclitaxel production of elicitor-treated Taxus yunnanensis cell cultures

Selection of a Digitalis purpurea Cell Line with Improved Bioconversion Capacity of Hydroquinone into Arbutin

This study aimed to investigate the biotransformation capabilities of a hydroquinone-tolerant Digitalis purpurea cell line (DpHQ) for bioconverting hydroquinone (HQ) into arbutin, a compound with significant therapeutic and cosmetic applications. The research evaluated the influence of various HQ concentrations, feeding protocols, and carbon sources on arbutin bioconversion yield. By using HPLC-MS for the quantification of arbutin in biomass and medium, the study revealed that higher precursor (HQ) concentration led to a more pronounced growth inhibition under single dosing than sequential dosing. At lower sugar (3%) and precursor (4 mM HQ) levels, arbutin predominantly remained within the cells, whereas higher sugar (6%) and HQ (5-6 mM) levels promoted its release into the medium. Arbutin production ranged from 591 mg/L under single dosing to 3049 mg/L with sequential dosing, with the highest yield being achieved with 5 mM HQ in divided doses and 6% glucose. This study holds novelty for being the first to demonstrate the DpHQ's tolerance to high concentrations of HQ and its efficient capabilities to bioconvert HQ to arbutin, indicating that D. purpurea is equipped with the enzymes required for this process. These aspects highlight its potential as a biotechnological source for arbutin synthesis.

A novel drying film culture method applying a natural phenomenon: Increased carotenoid production by Haematococcus sp

Low productivity and high cost remain major bottlenecks for the large-scale production of Haematococcus sp. This study explored biomass production and carotenoid accumulation in Haematococcus sp. (KCTC 12348BP) using drying film culture. The broth-cultured strain (3.2 × 106 cells/mL, 0.83 ± 0.02 mg/mL for a 21 d culture) was cultured under various conditions (different inoculum volumes and mist feeding intervals) in waterless agar plates at 28 ± 0.5 °C, under fluorescent light (12 h light-dark cycle) for 1 month. The maximum biomass obtained was 17.60 ± 0.72 g/m2, while the maximum astaxanthin concentration was 8.23 ± 1.13 mg/g in the culture using 1 mL inoculum and 3 d feeding interval. Drought stress in drying film culture effectively induced the accumulation of carotenoids from β-carotene, facilitating the production of canthaxanthin via the astaxanthin biosynthesis pathway. This cost-effective culture system can increase the biomass and carotenoid pigment production in Haematococcus sp.

Applications of synthetic biology in medical and pharmaceutical fields

Synthetic biology aims to design or assemble existing bioparts or bio-components for useful bioproperties. During the past decades, progresses have been made to build delicate biocircuits, standardized biological building blocks and to develop various genomic/metabolic engineering tools and approaches. Medical and pharmaceutical demands have also pushed the development of synthetic biology, including integration of heterologous pathways into designer cells to efficiently produce medical agents, enhanced yields of natural products in cell growth media to equal or higher than that of the extracts from plants or fungi, constructions of novel genetic circuits for tumor targeting, controllable releases of therapeutic agents in response to specific biomarkers to fight diseases such as diabetes and cancers. Besides, new strategies are developed to treat complex immune diseases, infectious diseases and metabolic disorders that are hard to cure via traditional approaches. In general, synthetic biology brings new capabilities to medical and pharmaceutical researches. This review summarizes the timeline of synthetic biology developments, the past and present of synthetic biology for microbial productions of pharmaceutics, engineered cells equipped with synthetic DNA circuits for diagnosis and therapies, live and auto-assemblied biomaterials for medical treatments, cell-free synthetic biology in medical and pharmaceutical fields, and DNA engineering approaches with potentials for biomedical applications.

Optimization of Medium Components for Fed-Batch Fermentation Using Central Composite Design to Enhance Lichenysin Production by Bacillus licheniformis Ali5

Lichenysin, an amphiphilic biosurfactant with structural and physicochemical properties similar to surfactin, is produced by Bacillus licheniformis. Its low toxicity, good environmental compatibility, solubilization, foaming, emulsification and detergent activities have led to a wide range of applications in agricultural biocontrol, enhanced oil recovery, foaming agents for cosmetics and detergents for household cleaning products. However, despite the extraordinary surface-active properties and potential applications of lichenysin, the number of wild bacteria found so far is relatively low. Low titers and high costs are the main limiting factors for widespread industrial applications. In this study, a factorial design was used to optimize the composition of the medium for the production of lichenysin by Bacillus licheniformis Ali5. Firstly, the solutions of carbon, nitrogen, amino acids, inorganic salts and trace elements in the medium were evaluated in flasks using a single-factor optimization method. Meanwhile, the operating conditions were optimized in the same way. Afterwards, a partial factorial design was used to investigate the effect of six variables (five medium compositions and inoculum size) on lichenysin production. Based on the results obtained, the concentrations of sucrose and ammonium nitrate and the inoculum size were considered to be important for lichenysin production. Subsequently, a full factorial design was used to optimize these three variables. The optimized medium composition were sucrose 19.8 g/L, NH4NO3 3.9 g/L, K2HPO4·3H2O 4.0 g/L, MgSO4·7H2O 0.6 g/L, FeSO4·7H2O 0.1 g/L, CaCl2 0.01 g/L, NaCl 3.0, trace elements 1.2 mL/L. Finally, the titer of lichenysin after fed-batch fermentation reached 1425.85 mg/L, which was approximately 5.5 times higher than the titer of lichenysin from the original medium. Consequently, the method was further demonstrated to be suitable for lichenysin production.

Cultivation of the gut bacterium Prevotella copri DSM 18205T using glucose and xylose as carbon sources

Prevotella copri DSM18205T is a human gut bacterium, suggested as a next-generation probiotic. To utilize it as such, it is, however, necessary to grow the species in a reproducible manner. Prevotella copri has previously been reported to be highly sensitive to oxygen, and hence difficult to isolate and cultivate. This study presents successful batch cultivation strategies for viable strain inoculations and growth in both serum bottles and a stirred tank bioreactor (STR), without the use of an anaerobic chamber, as long as the cells were kept in the exponential growth phase. A low headspace volume in the STR was important to reach high cell density. P. copri utilized xylose cultivated in Peptone Yeast Xylose medium (PYX medium), resulting in a comparable growth rate and metabolite production as in Peptone Yeast Glucose medium (PYG medium) in batch cultivations at pH 7.2.Up to 5 g/L of the carbon source was consumed, leading to the production of succinic acid, acetic acid, and formic acid, and cell densities (OD620 nm ) in the range 6-7.5. The highest yield of produced succinic acid was 0.63 ± 0.05 g/g glucose in PYG medium cultivations and 0.88 ± 0.06 g/g xylose in PYX medium cultivations.

The Deoxymiroestrol and Isoflavonoid Production and Their Elicitation of Cell Suspension Cultures of Pueraria candollei var. mirifica: from Shake Flask to Bioreactor

To address the high demand for Pueraria candollei var. mirifica (PM) used as the active ingredient in health products and its difficulty to cultivate in the field, the growth and production of deoxymiroestrol (DME) and isoflavonoid (ISF) phytoestrogens in PM cell suspensions were studied. In a 125-mL shake flask, the cell suspension produced DME [78.7 ± 8.79-116 ± 18.2 μg/g dry weight (DW)] and ISF (140 ± 6.83-548 ± 18.5 μg/g DW), which are the predominant ISF glycosides. While ISF aglycones accumulated in the PM cell suspension cultured in the airlift bioreactor. The DME content was increased to 976 ± 79.6 μg/g DW when the PM cell suspension was cultured in the 5-L scale bioreactor. The production of DME and ISF was enhanced by elicitors including methyl jasmonate (MJ), yeast extract (YE), and chitosan (CHI). MJ produced the highest induction of DME accumulation, while ISF accumulation was the highest with YE treatment. Analysis of catalase activity implied that the elicitors enhanced ROS production, which resulted in the enhancement of DME and ISF production and accumulation in PM cell suspension cultures. PM cell suspension culture is a promising source of beneficial PM phytoestrogens that exhibit bioactivity that may useful for the treatment of menopausal symptoms.

Biosynthesis of Silver Nanoparticles Using Taxus yunnanensis Callus and Their Antibacterial Activity and Cytotoxicity in Human Cancer Cells

Plant constituents could act as chelating/reducing or capping agents for synthesis of silver nanoparticles (AgNPs). The green synthesis of AgNPs has been considered as an environmental friendly and cost-effective alternative to other fabrication methods. The present work described the biosynthesis of AgNPs using callus extracts from Taxus yunnanensis and evaluated their antibacterial activities in vitro and potential cytotoxicity in cancer cells. Callus extracts were able to reduce silver nitrate at 1 mM in 10 min. Transmission electron microscope (TEM) indicated the synthesized AgNPs were spherical with the size range from 6.4 to 27.2 nm. X-ray diffraction (XRD) confirmed the AgNPs were in the form of nanocrystals. Fourier transform infrared spectroscopy (FTIR) suggested phytochemicals in callus extracts were possible reducing and capping agents. The AgNPs exhibited effective inhibitory activity against all tested human pathogen bacteria and the inhibition against Gram-positive bacteria was stronger than that of Gram-negative bacteria. Furthermore, they exhibited stronger cytotoxic activity against human hepatoma SMMC-7721 cells and induced noticeable apoptosis in SMMC-7721 cells, but showed lower cytotoxic against normal human liver cells (HL-7702). Our results suggested that biosynthesized AgNPs could be an alternative measure in the field of antibacterial and anticancer therapeutics.

Assessment of cultivation factors that affect biomass and geraniol production in transgenic tobacco cell suspension cultures

A large-scale statistical experimental design was used to determine essential cultivation parameters that affect biomass accumulation and geraniol production in transgenic tobacco (Nicotiana tabacum cv. Samsun NN) cell suspension cultures. The carbohydrate source played a major role in determining the geraniol yield and factors such as filling volume, inoculum size and light were less important. Sucrose, filling volume and inoculum size had a positive effect on geraniol yield by boosting growth of plant cell cultures whereas illumination of the cultures stimulated the geraniol biosynthesis. We also found that the carbohydrates sucrose and mannitol showed polarizing effects on biomass and geraniol accumulation. Factors such as shaking frequency, the presence of conditioned medium and solubilizers had minor influence on both plant cell growth and geraniol content. When cells were cultivated under the screened conditions for all the investigated factors, the cultures produced ∼ 5.2 mg/l geraniol after 12 days of cultivation in shaking flasks which is comparable to the yield obtained in microbial expression systems. Our data suggest that industrial experimental designs based on orthogonal arrays are suitable for the selection of initial cultivation parameters prior to the essential medium optimization steps. Such designs are particularly beneficial in the early optimization steps when many factors must be screened, increasing the statistical power of the experiments without increasing the demand on time and resources.

Quantitative proteomic profiling reveals photosynthesis responsible for inoculum size dependent variation in Chlorella sorokiniana

High density cultivation is essential to industrial production of biodiesel from microalgae, which involves in variations of micro-environment around individual cells, including light intensity, nutrition distribution, other abiotic stress and so on. To figure out the main limit factor in high inoculum cultivation, a quantitative proteomic analysis (iTRAQ-on-line 2-D nano-LC/MS) in a non-model green microalga, Chlorella sorokiniana, under different inoculum sizes was conducted. The resulting high-quality proteomic dataset consisted of 695 proteins. Using a cutoff of P < 0.05, 241 unique proteins with differential expression levels were identified between control and different inoculum sizes. Functional analysis showed that proteins participating in photosynthesis (light reaction) and Calvin cycle (carbon reaction pathway) had highest expression levels under inoculum size of 1 × 10(6) cells mL(-1), and lowest levels under 1 × 10(7) cells mL(-1). Canonical correlation analysis of the photosynthesis related proteins and metabolites biomarkers showed that a good correlation existed between them (canonical coefficient was 0.987), suggesting photosynthesis process greatly affected microalgae biodiesel productivity and quality. Proteomic study of C. sorokiniana under different illuminations was also conducted to confirm light intensity as a potential limit factor of high inoculum size. Nearly two thirds of proteins showed up-regulation under the illumination of 70-110 µmol m(-2) s(-1), compared to those of 40 µmol m(-2) s(-1). This result suggested that by elegantly adjusting light conditions, high cell density cultivation and high biodiesel production might be achieved.

Elicitation of andrographolide in the suspension cultures of Andrographis paniculata

Andrographis paniculata belonging to the family Acanthaceae produces a group of diterpene lactones, one of which is the pharmaceutically important-andrographolide. It is known to possess various important biological properties like anticancer, anti-HIV, anti-inflammatory, etc. This is the first report on the production of andrographolide in the cell suspension cultures of Andrographis paniculata by 'elicitation'. Elicitation was attempted to enhance the andrographolide content in the suspension cultures of Andrographis paniculata and also to ascertain its stimulation under stress conditions or in response to pathogen attack. The maximum andrographolide production was found to be 1.53 mg/g dry cell weight (DCW) at the end of stationary phase during the growth curve. The biotic elicitors (yeast, Escherichia coli, Bacillus subtilis, Agrobacterium rhizogenes 532 and Agrobacterium tumefaciens C 58) were more effective in eliciting the response when compared to the abiotic elicitors (CdCl(2), AgNO(3), CuCl(2) and HgCl(2)). Yeast has shown to stimulate maximum accumulation of 13.5 mg/g DCW andrographolide, which was found to be 8.82-fold higher than the untreated cultures.

Elicited Teucrium chamaedrys cell cultures produce high amounts of teucrioside, but not the hepatotoxic neo-clerodane diterpenoids

Teucrium chamaedrys, one of the most common and investigated species of the genus Teucrium, has been used for centuries in traditional medicine for many purposes. Its phytochemical components comprise, among others, phenylethanoid glycosides (PGs) and neo-clerodane diterpenoids. Several reports have demonstrated a wide range of beneficial biological and pharmacological activities of the phenylethanoid components, while the diterpenes were shown to be strongly hepatotoxic. In this work, in vitro cultures were established from leaf explants of T. chamaedrys. Both solid (callus) and liquid (cell suspension) cultures maintained the capacity to produce PGs, with teucrioside (TS) representing the most abundant one. Cell suspensions had a lower TS content than that found in leaf extracts, but higher than that of calli. An NMR-based metabolomics approach was used to compare the product profile of intact plants vs. cell suspension cultures, and results showed that neo-clerodane diterpenes, present in the intact plant, were not detected in cell cultures. Several elicitors were supplied to cell cultures with the aim of increasing TS production, and elicitation was tested at different growth phases and by exposing cells for different periods. Methyl jasmonate and fungal mycelia from Trichoderma viridae and Fusarium moniliforme were able to significantly increase TS production if supplied at the early-exponential growth phase for 24h. Based on the proposed link between proline and the phenylpropanoid pathways, proline accumulation in cell cultures was followed throughout a 14-day culture period, showing that it strictly reflected that of TS production. Moreover, exogenously supplied proline, and its analogue hydroxyproline, turned out to be very effective in increasing teucrioside production.

Enhanced benzophenanthridine alkaloid production and protein expression with combined elicitor in Eschscholtzia californica suspension cultures

Production of the benzophenanthridine alkaloids in Eschscholtzia californica suspension cell cultures was optimized by adding 0.5 mg methyl jasmonate (MJ) and 0.02 mg salicylic acid (SA)/g FCW after 7 days cultivation. Sanguinarine reached 24 mg/g DCW by such treatment; 10 times higher than in control cell cultures. MJ and SA induced expression of berberine bridge enzyme and 3'-hydroxy-(S)-N-methylcoclaurine-4'-O-methyltransferase, respectively. MJ plus SA induced over-expression of both enzymes.

The effect of heat shock on paclitaxel production in Taxus yunnanensis cell suspension cultures: role of abscisic acid pretreatment

The heat shock (HS) response is a conserved cellular defense mechanism to elevated temperatures, observed in cells from bacteria to human. It is characterized by the increased accumulation of HS proteins. This work examines the effect of HS on the secondary metabolite biosynthesis of cultured plant cells. Suspension cultures of Taxus yunnanensis cells, which produce the anticancer diterpenoid paclitaxel (Taxol), were heat shocked at 35-50 degrees C for 30-60 min. The results show that HS reduced cell viability and growth but significantly induced paclitaxel production. The HS-induced paclitaxel production depended on the intensity of HS and the physiological state of the cells. Abscisic acid (ABA)-pretreatment not only increased cell viability and growth upon HS but also improved HS-induced paclitaxel yield. The best culture phase to apply the HS was the late-exponential growth phase. Under the optimized condition, HS enhanced paclitaxel yield by sixfold to 6.8 mg/L. In addition, a prior mild-HS treatment also significantly increased HS-induced paclitaxel production. Furthermore, HS induced oxidative burst, the early event of plant defense response to pathogen attack and other stress challenge; the addition of putative inhibitors of lipoxygenase, a key enzyme for jasmonic acid biosynthesis, significantly inhibited HS-induced pacliatxel accumulation. The stimulation of secondary metabolite production by HS may be a result of HS-induced plant cell defense response.

Taxanes: perspectives for biotechnological production

Taxol is a valuable plant-derived drug showing activity against various cancer types. Worldwide efforts had been made to overcome the supply problem, because the supply by isolation from the bark of the slow-growing yew trees is limited. Plant cell cultures as well as chemical and biotechnological semisynthesis are processes, which are intensively investigated for the production of taxanes paclitaxel (Taxol) and docetaxel (Taxotere) in the last few years. This article provides a comparison of the current research on taxane biosynthesis and production in yew cell cultures.

Image analysis and in vivo imaging as tools for investigation of productivity dynamics in anthocyanin-producing cell cultures of Daucus carota

An anthocyanin-producing suspension culture of Daucus carota (L.) cv. Flakkese was used as model system to study secondary metabolite production in cell culture at the individual cell level. An approach was set up in which growth and production of anthocyanins were investigated using a combination of biochemical analysis, image (colour) analysis and in vivo imaging. This novel approach was used to segment the culture in different subpopulations and dissect the productive process in the cell culture grown under two different conditions, known to differ mainly for oxygen supply and mixing intensity (volume of 50 ml or 20 ml in 250 ml flasks). The 20 ml batch cultures gave a higher content and yield of anthocyanins, which depended on a complex balance between events that positively or negatively affected anthocyanin production. A model is proposed in which the different ability of cells to respond to environmental stimuli and stress depends on the different amount of anthocyanins accumulated within cells.

A novel synthetic fluoro-containing jasmonate derivative acts as a chemical inducing signal for plant secondary metabolism

A novel fluoro-containing jasmonate derivative was chemically synthesized and evaluated as a potential elicitor with respect to the induction of plant defense responses and the biosynthesis of plant secondary metabolites. A bioactive taxuyunnanine C (Tc)-producing cell line of Taxus chinensis was taken as a model plant cell system. The presence of novel synthesized pentafluoropropyl jasmonate (PFPJA) induced two early and important events in plant defense responses, including an oxidative burst and activation of L-phenylalanine ammonia lyase. In addition, PFPJA was found to significantly increase Tc accumulation, without any inhibition of cell growth. Moreover, Tc accumulation was increased more in the presence of PFPJA compared with methyl jasmonate (MJA) and previously reported trifluoroethyl jasmonate (TFEJA). For example, addition of 100 muM PFPJA on day 7 led to a high Tc content (38.2 +/- 0.3 mg/g) at day 21, while the Tc content was 29.3 +/- 0.3 mg/g and 34.9 +/- 0.9 mg/g with the addition of 100 microM MJA and TFEJA, respectively. Quantitative structure-activity analysis of fluoro-containing jasmonates suggests that the increase in the fluoro-groups introduced into the carboxyl side-chain of MJA resulted in a higher stimulatory activity for Tc biosynthesis, which corresponds well with the markedly increased lipophilicity after fluorine introduction. These results indicate that newly synthesized fluoro-containing PFPJA can act as a powerful chemical inducing signal for secondary metabolism in plant cell cultures.

Cell cycle analysis ofTaxus suspension cultures at the single cell level as an indicator of culture heterogeneity

Single cell growth and division was measured via flow cytometry in order to characterize the metabolic variability of Taxus cuspidata suspension cultures, which produce the valuable secondary metabolite Taxol. Good agreement was observed between the cell cycle distribution and biomass accumulation over the batch culture period. Specific growth rates of 0.13 days(-1) by fresh weight and 0.15 days(-1) by dry weight were measured. Elicitation with methyl jasmonate (MJ) significantly decreased both cell cycle progression and biomass accumulation, as the specific growth rate decreased to 0.027 days(-1) by fresh and dry weight. Despite the decrease in biomass accumulation for MJ elicited cultures, sucrose utilization was not significantly different from control cultures. MJ elicitation also increased the accumulation of paclitaxel and other taxanes. The accumulation of upstream taxanes (baccatin III and 10-deactylbaccatin III) increased during exponential growth, reached a maximum around day 12, and then declined throughout the stationary phase. The paclitaxel concentration increased during both exponential growth and stationary phase, reaching a maximum around days 20-25. Throughout the culture period, greater than 70% of the cells were in G(0)/G(1) phase of the cell cycle. Studies using bromodeoxyuridine (BrdU) incorporation showed that approximately 65% of the Taxus cells are noncycling, even during exponential growth. Although the role of these cells is currently unknown, the presence of a large, noncycling subpopulation can have a significant impact on the utilization of plant cell culture technology for the large-scale production of paclitaxel. These results demonstrate that there is a high degree of metabolic heterogeneity in Taxus cuspidata suspension cultures. Understanding this heterogeneity is important for the optimization of plant cell cultures, particularly the reduction of production variability.

Novel synthetic jasmonates as highly efficient elicitors for taxoid production by suspension cultures ofTaxus chinensis

Suspension cultures of Taxus chinensis were used as a model plant cell system to evaluate novel synthetic jasmonates as elicitors for stimulating the biosynthesis of secondary metabolites. Significant increases in accumulation of taxuyunnanine C (Tc) were observed in the presence of newly synthesized 2-hydroxyethyl jasmonate (HEJA) and trifluoroethyl jasmonate (TFEJA) without their inhibition on cell growth. Addition of 100 microM HEJA or TFEJA on day 7 led to a high Tc content of 44.3 +/- 1.1mg/g or 39.7 +/- 1.1 mg/g (at day 21), while the Tc content was 14.0 +/- 0.1 mg/g and 32.4 +/- 1.6 mg/g for the control and that with addition of 100 microM methyl jasmonate (MJA), respectively. The superior stimulating ability of HEJA and TFEJA over MJA, which was generally considered as the best chemical for eliciting taxoid biosynthesis, suggests that the novel jasmonate analogues may have great potential in application to other cell culture systems for effcient elicitation of plant secondary metabolites.