Home About us Contact
|
Home About us Contact | ||
|
|
||
Hairy Root Cultures (hairy + root_culture)
Selected AbstractsHairy Root Culture in a Liquid-Dispersed Bioreactor: Characterization of Spatial HeterogeneityBIOTECHNOLOGY PROGRESS, Issue 3 2000Gary R. C. Williams A liquid-dispersed reactor equipped with a vertical mesh cylinder for inoculum support was developed for culture of Atropa belladonna hairy roots. The working volume of the culture vessel was 4.4 L with an aspect ratio of 1.7. Medium was dispersed as a spray onto the top of the root bed, and the roots grew radially outward from the central mesh cylinder to the vessel wall. Significant benefits in terms of liquid drainage and reduced interstitial liquid holdup were obtained using a vertical rather than horizontal support structure for the biomass and by operating the reactor with cocurrent air and liquid flow. With root growth, a pattern of spatial heterogeneity developed in the vessel. Higher local biomass densities, lower volumes of interstitial liquid, lower sugar concentrations, and higher root atropine contents were found in the upper sections of the root bed compared with the lower sections, suggesting a greater level of metabolic activity toward the top of the reactor. Although gas-liquid oxygen transfer to the spray droplets was very rapid, there was evidence of significant oxygen limitations in the reactor. Substantial volumes of non-free-draining interstitial liquid accumulated in the root bed. Roots near the bottom of the vessel trapped up to 3,4 times their own weight in liquid, thus eliminating the advantages of improved contact with the gas phase offered by liquid-dispersed culture systems. Local nutrient and product concentrations in the non-free-draining liquid were significantly different from those in the bulk medium, indicating poor liquid mixing within the root bed. Oxygen enrichment of the gas phase improved neither growth nor atropine production, highlighting the greater importance of liquid-solid compared with gas-liquid oxygen transfer resistance. The absence of mechanical or pneumatic agitation and the tendency of the root bed to accumulate liquid and impede drainage were identified as the major limitations to reactor performance. Improved reactor operating strategies and selection or development of root lines offering minimal resistance to liquid flow and low liquid retention characteristics are possible solutions to these problems. [source] Biotransformation of 4-Hydroxybenzen Derivatives by Hairy Root Cultures of Polygonum multiflorum Thunb.JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 2 2007Chun-Yan Yan Abstract The biotransformation of four 4-hydroxybenzen derivatives (1,4-benzenediol (compound 1), 4-hydroxybenzaldehyde (compound 2), 4-hydroxybenzyl alcohol (compound 3) and 4-hydroxybenzoic acid (compound 4)) by the hairy root cultures of Polygonum multiflorum Thunb. as a new biocatalyst was investigated. It was found that the substrates were transformed to their corresponding glucosides, 4-hydroxyphenyl ,- D -glucopyranoside (arbutin, compound 1a), 4-hydroxymethylphenyl ,- D -glucopyranoside (gastrodin, compounds 2a, 3a) and 4-carboxyphenyl ,- D -glucopyranoside (compound 4a), respectively. In the meantime, the hairy roots of P. multiflorum were able to stereoselectively and regioselectively glucosylate phenolic hydroxyl groups of compounds 1,4, but the cultures could not glucosylate the aldehyde group of compound 2 or the benzylic hydroxyl group of compound 3, and no glucosyl esterification of carboxyl groups of compound 4 was detected. On the other hand, the result also showed that the hairy roots of P. multiflorum were able to reduce the 4-hydroxybenzaldehyde to its corresponding alcohol. This is the first report that substrate 4 has been converted into its ,- D -glucopyranoside by a plant biotransformation system. [source] Hairy Root and Its Application in Plant Genetic EngineeringJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 2 2006Zhi-Bi Hu Abstract Agrobacterium rhizogenes Conn. causes hairy root disease in plants. Hairy root-infected A. rhizogenes is characterized by a high growth rate and genetic stability. Hairy root cultures have been proven to be an efficient means of producing secondary metabolites that are normally biosynthesized in roots of differentiated plants. Furthermore, a transgenic root system offers tremendous potential for introducing additional genes along with the Ri plasmid, especially with modified genes, into medicinal plant cells with A. rhizogenes vector systems. The cultures have turned out to be a valuable tool with which to study the biochemical properties and the gene expression profile of metabolic pathways. Moreover, the cultures can be used to elucidate the intermediates and key enzymes involved in the biosynthesis of secondary metabolites. The present article discusses various applications of hairy root cultures in plant genetic engineering and potential problems associated with them. (Managing editor: Wei Wang) [source] Expression of tropane alkaloids in the hairy root culture of Atropa acuminata substantiated by DART mass spectrometric techniqueBIOMEDICAL CHROMATOGRAPHY, Issue 8 2008Suchitra Banerjee Abstract Agrobacterium rhizogenes -mediated ,hairy root' cultures were established in Atropa acuminata. The chemical profiling of the hairy roots was carried out by a new mass spectrometric technique, direct analysis in real time (DART). The intact hairy roots were directly analyzed by holding them in the gap between the DART ion source and mass spectrometer. Two alkaloids, atropine and scopolamine, were characterized. The structural confirmation of the two alkaloids was made through their accurate molecular formula determinations. This is the first report of establishing hairy roots in A. acuminata as well as application of the DART technique for the chemical profiling of its hairy roots. Copyright © 2008 John Wiley & Sons, Ltd. [source] Biotransformation of 4-Hydroxybenzen Derivatives by Hairy Root Cultures of Polygonum multiflorum Thunb.JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 2 2007Chun-Yan Yan Abstract The biotransformation of four 4-hydroxybenzen derivatives (1,4-benzenediol (compound 1), 4-hydroxybenzaldehyde (compound 2), 4-hydroxybenzyl alcohol (compound 3) and 4-hydroxybenzoic acid (compound 4)) by the hairy root cultures of Polygonum multiflorum Thunb. as a new biocatalyst was investigated. It was found that the substrates were transformed to their corresponding glucosides, 4-hydroxyphenyl ,- D -glucopyranoside (arbutin, compound 1a), 4-hydroxymethylphenyl ,- D -glucopyranoside (gastrodin, compounds 2a, 3a) and 4-carboxyphenyl ,- D -glucopyranoside (compound 4a), respectively. In the meantime, the hairy roots of P. multiflorum were able to stereoselectively and regioselectively glucosylate phenolic hydroxyl groups of compounds 1,4, but the cultures could not glucosylate the aldehyde group of compound 2 or the benzylic hydroxyl group of compound 3, and no glucosyl esterification of carboxyl groups of compound 4 was detected. On the other hand, the result also showed that the hairy roots of P. multiflorum were able to reduce the 4-hydroxybenzaldehyde to its corresponding alcohol. This is the first report that substrate 4 has been converted into its ,- D -glucopyranoside by a plant biotransformation system. [source] Hairy Root and Its Application in Plant Genetic EngineeringJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 2 2006Zhi-Bi Hu Abstract Agrobacterium rhizogenes Conn. causes hairy root disease in plants. Hairy root-infected A. rhizogenes is characterized by a high growth rate and genetic stability. Hairy root cultures have been proven to be an efficient means of producing secondary metabolites that are normally biosynthesized in roots of differentiated plants. Furthermore, a transgenic root system offers tremendous potential for introducing additional genes along with the Ri plasmid, especially with modified genes, into medicinal plant cells with A. rhizogenes vector systems. The cultures have turned out to be a valuable tool with which to study the biochemical properties and the gene expression profile of metabolic pathways. Moreover, the cultures can be used to elucidate the intermediates and key enzymes involved in the biosynthesis of secondary metabolites. The present article discusses various applications of hairy root cultures in plant genetic engineering and potential problems associated with them. (Managing editor: Wei Wang) [source] Oxytetracycline inactivation by putative reactive oxygen species released to nutrient medium of Helianthus annuus hairy root cultures,BIOTECHNOLOGY & BIOENGINEERING, Issue 4 2005Ninad P. Gujarathi Abstract When subjected to stress, plants produce reactive oxygen species (ROS) as a part of the defense response. The oxidative response is also used to degrade organic pollutants. Hairy roots of Helianthus annuus (sunflower) are shown to oxidize oxytetracycline (OTC) through the action of the ROS released to the nutrient medium by the hairy root cultures. Methyl jasmonate (MeJA) elicits ROS formation in the hairy root cultures. The activities of the antioxidant enzymes, ascorbate peroxidase (APX), catalase (CAT), and guaiacol peroxidase (GPX), are reported for hairy root cultures treated with increasing concentrations of MeJA. A bioassay using Enterococcus hirae as the test microorganism demonstrates the root-catalyzed oxidation process results in conversion of OTC into product(s) devoid of antibiotic activity. Direct evidence for putative ROS oxidation of OTC is obtained by mass spectrometry (MS) and HPLC/MS showing first quinone formation followed possibly by ring cleavage, which disrupts UV absorption and destroys antibiotic activity. © 2005 Wiley Periodicals, Inc. [source] Assessing the limitations to terpenoid indole alkaloid biosynthesis in Catharanthus roseus hairy root cultures through gene expression profiling and precursor feedingBIOTECHNOLOGY PROGRESS, Issue 5 2009Sheba Goklany Abstract The production of pharmaceutically important terpenoid indole alkaloids (TIAs) from Catharanthus roseus is partly regulated at the transcriptional level. In this study, limitations in TIA biosynthesis from C. roseus hairy root cultures were assessed through gene expression profiling and precursor feeding. The transcript levels of key TIA pathway genes (G10h, Tdc, Str, and Sgd) and metabolite levels associated with the TIA pathway (tryptamine, loganin, secologanin, strictosidine, ajmalicine, serpentine, and tabersonine) were monitored using quantitative RT-PCR and HPLC, respectively. In cultures elicited with methyl jasmonate (250 ,M MeJA on day 21), G10h, Tdc, Str, and Sgd expression increased by 9.1, 3.1, 6.7, and 8.3-fold, respectively, after 24 h. Up-regulation of gene expression was followed by a 160, 440, and 420% increase in strictosidine, ajmalicine, and tabersonine levels, respectively, after 5 days. Precursors loganin, tryptamine, or their combination were fed to noninduced and MeJA-induced cultures to complement the above studies. TIA production was not significantly enhanced in either noninduced or MeJA-induced cultures with precursor feeding. In noninduced cells, steps downstream of loganin and tryptamine were limiting (SLS, STR, or SGD) because either loganin or tryptamine accumulated in the cells with precursor feeding. These bottlenecks were partly overcome in MeJA-induced cultures as the expression of Str and Sgd genes and TIA production increased. However, secologanin accumulated in MeJA-induced cultures with precursor feeding, suggesting that STR was likely limiting under MeJA-induced conditions. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Heterologous Expression of Vitreoscilla Hemoglobin (VHb) and Cultivation Conditions Affect the Alkaloid Profile of Hyoscyamus muticus Hairy RootsBIOTECHNOLOGY PROGRESS, Issue 2 2006Annika Wilhelmson Fast-growing hairy root cultures of Hyoscyamus muticus induced by Agrobacterium rhizogenes offer a potential production system for tropane alkaloids. Oxygen deficiency has been shown to limit growth and biomass accumulation of hairy roots, whereas little experimental data is available on the effect of oxygen on alkaloid production. We have investigated the effect of Vitreoscilla hemoglobin (VHb) expression and cultivation conditions on the complete alkaloid profile of H. muticus hairy roots in shake flasks and in a laboratory scale bioreactor. We optimized the growth medium composition and studied the effects of sucrose, ammonium, nitrate, and phosphate on growth and alkaloid production. Maximum biomass accumulation was achieved with the highest and maximum hyoscyamine content with the lowest sucrose concentration. The optimum nitrate concentration for growth was higher for the VHb line than the control. Neither VHb expression nor aeration improved the hyoscyamine content significantly, thus suggesting that hyoscyamine biosynthesis is not limited by oxygen availability. Interestingly, the effect of VHb expression on the alkaloid profile was slightly different from that of aeration. VHb expression did not affect the concentrations of cuscohygrine, which was increased by aeration. Therefore, the effect of VHb is probably not related only to its ability to increase the intracellular effective oxygen concentration. [source] Expression of tropane alkaloids in the hairy root culture of Atropa acuminata substantiated by DART mass spectrometric techniqueBIOMEDICAL CHROMATOGRAPHY, Issue 8 2008Suchitra Banerjee Abstract Agrobacterium rhizogenes -mediated ,hairy root' cultures were established in Atropa acuminata. The chemical profiling of the hairy roots was carried out by a new mass spectrometric technique, direct analysis in real time (DART). The intact hairy roots were directly analyzed by holding them in the gap between the DART ion source and mass spectrometer. Two alkaloids, atropine and scopolamine, were characterized. The structural confirmation of the two alkaloids was made through their accurate molecular formula determinations. This is the first report of establishing hairy roots in A. acuminata as well as application of the DART technique for the chemical profiling of its hairy roots. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||