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Cell suspension culture of C. roseus in a stirred-tank bioreactor was subjected to a 6 h anaerobic period at intervals of 42 h. The anaerobic treatments resulted in the inhibition of cell growth, a reduction in cell viability, and an... more
Cell suspension culture of C. roseus in a stirred-tank bioreactor was subjected to a 6 h anaerobic period at intervals of 42 h. The anaerobic treatments resulted in the inhibition of cell growth, a reduction in cell viability, and an increase in the pH of medium and ethanol production. However, the injured responses to anaerobiosis could recover to varying degrees when the culture was transferred to aerobic conditions, indicating that no permanent, irreversible injury to the culture has been caused by the short anaerobic period (6h). The activities of secondary metabolism, the production of ajmalicine and catharanthine, reacted to anaerobic stress in different ways. Anaerobic stress did not significantly affect ajmalicine production but triggered the biosynthesis of catharanthine. Anaerobic stress stimulated the release of these alkaloids from cells into the medium.
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ABSTRACT This study reports a novel method for embryo separation by cold treatment of heterogeneous suspension cultures which contain embryogenic single cells, cell clusters and embryos at various stages of development. The method was... more
ABSTRACT This study reports a novel method for embryo separation by cold treatment of heterogeneous suspension cultures which contain embryogenic single cells, cell clusters and embryos at various stages of development. The method was applied to embryo suspension cultures of pepper (Capsicum annuum) and sugarcane (Saccharum officinarum). In both plants, single cells lost their viability dramatically over a few days while the viability of embryos remained above 95% for 25-30 days when kept at 5 °C. The effect of duration of cold treatment on embryo germination was also tested. The optimal duration of cold treatment was found to be 10 days for sugarcane and 21 days for pepper. After the cold treatment, the germination percentages were 90% and 96% for sugarcane and pepper, respectively.
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Plants have always provided food, fuel, food additives, drugs, pesticides, pigments, resins, perfumes and other important industrial, medicinal and agricultural raw materials. The techniques of plant, organ, tissue and cell culture have... more
Plants have always provided food, fuel, food additives, drugs, pesticides, pigments, resins, perfumes and other important industrial, medicinal and agricultural raw materials. The techniques of plant, organ, tissue and cell culture have evolved since the beginning of this century and combined with recent advances in genetics and using conventional plant breeding, the plant biotechnology is having a significant impact on agriculture, horticulture and forestry. Some examples of the current applications in agriculture are micropropagation, somatic embryogenesis, virus and pathogen elimination, embryo rescue, germplasm storage and plant modification by somaclonal variation and genetic engineering. Another significant potential of plant biotechnology is in vitro production of fine chemicals using plant cell/organ cultures. However, there are several problems associated with such production technologies and the commercial processes are confined to a few examples, mainly in Japan. The whole field of plant biotechnology is expanding fast; with increased understanding of plant biochemistry, molecular biology, physiology and parallel developments in analytical sciences, instrumentation, bioreactor design and downstream processing the future can hold exciting possibilities.
Research Interests:
Research Interests:
The Wageningen UR Library Catalogue contains bibliographic data on books and periodicals held by the libraries of Wageningen University and Research Centre and some 15 associated libraries. Holding data are added to each record. ...... more
The Wageningen UR Library Catalogue contains bibliographic data on books and periodicals held by the libraries of Wageningen University and Research Centre and some 15 associated libraries. Holding data are added to each record. ... Subjects covered include Agrotechnology, Food and Food Production, Plant and Animal Sciences, Soil Science, Geo-information, Landscape and Spatial Planning, Water and Climate, Ecosystem Studies, Economics and Society. ... The joint collections of the participating libraries cover a substantial part of ...
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Scale-up has been one of the major problems in bioprocess technology. Earlier methods of trial-and-error have now been replaced by those which involve the understanding of the fundamental phenomena, at least for the simpler cases. For... more
Scale-up has been one of the major problems in bioprocess technology. Earlier methods of trial-and-error have now been replaced by those which involve the understanding of the fundamental phenomena, at least for the simpler cases. For more complicated heterogeneous systems the employment of various rules of thumb is still widely practised. A summary of various strategies for bioreactor scale-up is given below.
Research Interests:
The aim of this work was to investigate the interaction between E.coli and Streptomyces coelicolor A3 (2) for the increased production of undecylprodigiosin and identify the E. coli actives mediating this inter-species interaction. The... more
The aim of this work was to investigate the interaction between E.coli and Streptomyces coelicolor A3 (2) for the increased production of undecylprodigiosin and identify the E. coli actives mediating this inter-species interaction. The antibiotics of interest were the red-pigmented undecylprodigiosin and blue-pigmented actinorhodin. Pure cultures of S. coelicolor in a defined medium produced higher concentrations of actinorhodin compared to those of undecylprodigiosin. The latter however, is more important due to its immunosuppressive and antitumor properties. As a strategy to increase undecylprodigiosin production, we added separately, live cells and heat-killed cells of E. coli C600, and the cell-free supernatant of E. coli culture to S. coelicolor cultures in shake flasks. The interaction with live cells of E. coli altered the antibiotic production pattern and undecylprodigiosin production was enhanced by 3.5-fold compared to the pure cultures of S. coelicolor and actinorhodin decreased by 15-fold. The heat-killed cells of E. coli however, had no effect on antibiotic production. In all cases, growth and glucose consumption of S. coelicolor remained almost the same as those observed in the pure culture indicating that the changes in antibiotic production were not due to nutritional stress. Results with cell-free supernatant of E. coli culture indicated that the interaction between S. coelicolor and E. coli was mediated via diffusible molecule(s). Using a set of extraction procedures and agar-well diffusion bioassays, we isolated and preliminarily identified a class of compounds. For the preliminary verification, we added the compound which was the common chemical structural moiety in this class of compounds to the pure S. coelicolor cultures. We observed similar effects on antibiotic production as with the live E. coli cells and their supernatant indicating that this class of compounds secreted by E. coli indeed could act as actives during interspecies interaction and increase the production of undecylprodigiosin.
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Research Interests:
Research Interests:
Cell immobilisation in pre-formed carriers involves passive/natural immobilisation usually in situ in the bioreactors or in the culture environment. Numerous inorganic and organic materials have been used as pre-formed carriers:... more
Cell immobilisation in pre-formed carriers involves passive/natural immobilisation usually in situ in the bioreactors or in the culture environment. Numerous inorganic and organic materials have been used as pre-formed carriers: reticulated polyurethane and polyvinyl formal foam, other polymers, plastics, stainless steel, ceramic, glass, synthetic (ion exchange) resins, activated charcoal, aluminium oxide, diatomaceous earth, sand, cellulose, lignocellulose, cellulose acetate, and others. In this chapter however, only polyurethane foam, stainless steel knitted mesh, ceramic, glass and cellulose will be considered.
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Streptomyces coelicolor was immobilised "naturally" in porous support materials and its growth, glucose uptake and actinorhodin production were compared with freely suspended culture using defined and complex media. When... more
Streptomyces coelicolor was immobilised "naturally" in porous support materials and its growth, glucose uptake and actinorhodin production were compared with freely suspended culture using defined and complex media. When the defined medium was used, the most pronounced difference between the two cultures was the accumulation of actinorhodin extracellularly in freely suspended and intracellularly in immobilised cultures. In the complex medium, however, actinorhodin was excreted by both cultures. In addition, the complex medium yielded 50 times as much actinorhodin compared to the defined medium. Further increases in product concentration were obtained by repeated batches of immobilised culture, which showed stability for at least 3 months.
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ABSTRACT A protocol was developed for regeneration of pepper (Capsicum annuum var. Ace) through somatic embryogenesis in liquid media. For embryogenic callus formation, mature zygotic embryo explants were used on basal Murashige and Skoog... more
ABSTRACT A protocol was developed for regeneration of pepper (Capsicum annuum var. Ace) through somatic embryogenesis in liquid media. For embryogenic callus formation, mature zygotic embryo explants were used on basal Murashige and Skoog medium with 9.05 M 2,4-dichlorophenoxyacetic acid and 3% sucrose. Embryogenic callus was transferred to liquid basal Murashige and Skoog medium with 4.52 M 2,4-dichlorophenoxyacetic acid and 3% sucrose in order to increase the mass of the embryogenic culture. After pretreatment with potassium citrate, cells were placed into embryo initiation medium with 6 g l-1 l-proline and a decreased (10 mM) ammonium concentration. Embryos were matured in 1.89 M abscisic acid containing half-strength Murashige and Skoog medium and converted into plants bothin vivo andin vitro at up to a 97% efficiency.
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Research Interests: Microbiology, Production, Biology, Medicine, Multidisciplinary, and 14 moreBioreactor, Streptomyces coelicolor, Bacteria, Staphylococcus aureus, Prodigiosin, Secondary Metabolites, Physiological Response, Applied Microbiology and Biotechnology, Anti-Bacterial Agents, Elicitation, Bacillus subtilis, Microbial Interactions, Bioreactors, and Antitumor Activity
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A stoichiometric model was developed for the application of metabolic flux balance analysis (FBA) which consisted of the primary metabolic network of Arabidopsis thaliana (A. thaliana). The basic metabolic model involved 149 metabolites... more
A stoichiometric model was developed for the application of metabolic flux balance analysis (FBA) which consisted of the primary metabolic network of Arabidopsis thaliana (A. thaliana). The basic metabolic model involved 149 metabolites and 178 reactions that represent the main carbon metabolism towards the formation of biomass. Assuming pseudo-steady state, mass balances were performed for each metabolite and the resulting equations were solved using linear optimization. The optimal metabolic flux distribution was determined in General Algebraic Modeling System (GAMS) 23.0 software by setting up the objective function as the maximization of biomass formation rate and using the constraints from batch experiments of A. thaliana suspended cell cultures. The results gave the theoretical maximum biological capacity of the cells to grow for a given specific uptake rate of sugar. The model proved to be a good starting point for more extended version of metabolism specifically for secondary metabolite production. Addition or extension of the model is feasible.
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Metabolic flux analysis was applied to Streptomyces coelicolor growth under nitrogen limitation with nitrate or ammonia as the nitrogen source. In all cases, maximum specific growth rates corresponding to the same specific glucose uptake... more
Metabolic flux analysis was applied to Streptomyces coelicolor growth under nitrogen limitation with nitrate or ammonia as the nitrogen source. In all cases, maximum specific growth rates corresponding to the same specific glucose uptake rates were calculated in addition to the fluxes of some 200 metabolic reactions. Use of nitrate resulted in lower specific growth rates compared to ammonia. Excretion of some organic metabolites was observed in both limitation cases.
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SummaryA graphical method is described depicting the relationship between the physical oxygen transfer rate and microbial oxygen uptake rate in order to help determine the conditions under which growth will not be limited by oxygen.
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Abstract. A metabolic model was constructed in matrix formalism for the hydrogen production by the purple non-sulfur bacteria Rhodobacter sphaeroides involving 183 reactions and 153 metabolites. Assuming pseudo-steady state, mass balances... more
Abstract. A metabolic model was constructed in matrix formalism for the hydrogen production by the purple non-sulfur bacteria Rhodobacter sphaeroides involving 183 reactions and 153 metabolites. Assuming pseudo-steady state, mass balances were performed for each metabolite and the resulting equations were solved using optimization. The objective function was the maximization of hydrogen production. The comparison of experimental and computational results indicated the importance of light in hydrogen production.
Research Interests: Chemistry and Bioprocess
Research Interests:
Arabidopsis thaliana (A. thaliana) is a small weed which is related to the cabbage and mustard family. This flowering plant has been used widely as a model plant in genetics and molecular biology research since it is the first plant the... more
Arabidopsis thaliana (A. thaliana) is a small weed which is related to the cabbage and mustard family. This flowering plant has been used widely as a model plant in genetics and molecular biology research since it is the first plant the full sequenced genome. Thus, A. thaliana literature provides plentiful information from genomics and transcriptomics point of view. However, there is still a lack of physiological information regarding its cell suspension cultures which can be powerful research tools in Plant Biotechnology and especially in Plant Systems and Synthetic Biology. In this study, cell growth and sugar uptake of A. thaliana Col ecotype grown in the continuous dark condition were modelled using the modified Monod and Michelis-menten equations. The model included sucrose hydrolysis by the cell-wall invertase enzyme into hexoses (glucose and fructose) and consumption of these hexoses at different rates to support cell growth. All kinetic model parameters were obtained from a ...
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Research Interests:
The aim of this work was to investigate the interaction between E.coli and Streptomyces coelicolor A3 (2) for the increased production of undecylprodigiosin and identify the E. coli actives mediating this inter-species interaction. The... more
The aim of this work was to investigate the interaction between E.coli and Streptomyces coelicolor A3 (2) for the increased production of undecylprodigiosin and identify the E. coli actives mediating this inter-species interaction. The antibiotics of interest were the red-pigmented undecylprodigiosin and blue-pigmented actinorhodin. Pure cultures of S. coelicolor in a defined medium produced higher concentrations of actinorhodin compared to those of undecylprodigiosin. The latter however, is more important due to its immunosuppressive and antitumor properties. As a strategy to increase undecylprodigiosin production, we added separately, live cells and heat-killed cells of E. coli C600, and the cell-free supernatant of E. coli culture to S. coelicolor cultures in shake flasks. The interaction with live cells of E. coli altered the antibiotic production pattern and undecylprodigiosin production was enhanced by 3.5-fold compared to the pure cultures of S. coelicolor and actinorhodin decreased by 15-fold. The heat-killed cells of E. coli however, had no effect on antibiotic production. In all cases, growth and glucose consumption of S. coelicolor remained almost the same as those observed in the pure culture indicating that the changes in antibiotic production were not due to nutritional stress. Results with cell-free supernatant of E. coli culture indicated that the interaction between S. coelicolor and E. coli was mediated via diffusible molecule(s). Using a set of extraction procedures and agar-well diffusion bioassays, we isolated and preliminarily identified a class of compounds. For the preliminary verification, we added the compound which was the common chemical structural moiety in this class of compounds to the pure S. coelicolor cultures. We observed similar effects on antibiotic production as with the live E. coli cells and their supernatant indicating that this class of compounds secreted by E. coli indeed could act as actives during interspecies interaction and increase the production of undecylprodigiosin.
Research Interests:
Research Interests:
Research Interests:
Scale-up has been one of the major problems in bioprocess technology. Earlier methods of trial-and-error have now been replaced by those which involve the understanding of the fundamental phenomena, at least for the simpler cases. For... more
Scale-up has been one of the major problems in bioprocess technology. Earlier methods of trial-and-error have now been replaced by those which involve the understanding of the fundamental phenomena, at least for the simpler cases. For more complicated heterogeneous systems the employment of various rules of thumb is still widely practised. A summary of various strategies for bioreactor scale-up is given below.
Research Interests:
Plants have always provided food, fuel, food additives, drugs, pesticides, pigments, resins, perfumes and other important industrial, medicinal and agricultural raw materials. The techniques of plant, organ, tissue and cell culture have... more
Plants have always provided food, fuel, food additives, drugs, pesticides, pigments, resins, perfumes and other important industrial, medicinal and agricultural raw materials. The techniques of plant, organ, tissue and cell culture have evolved since the beginning of this century and combined with recent advances in genetics and using conventional plant breeding, the plant biotechnology is having a significant impact on agriculture, horticulture and forestry. Some examples of the current applications in agriculture are micropropagation, somatic embryogenesis, virus and pathogen elimination, embryo rescue, germplasm storage and plant modification by somaclonal variation and genetic engineering. Another significant potential of plant biotechnology is in vitro production of fine chemicals using plant cell/organ cultures. However, there are several problems associated with such production technologies and the commercial processes are confined to a few examples, mainly in Japan. The whole field of plant biotechnology is expanding fast; with increased understanding of plant biochemistry, molecular biology, physiology and parallel developments in analytical sciences, instrumentation, bioreactor design and downstream processing the future can hold exciting possibilities.
Research Interests:
Research Interests:
RESUMO As bactérias da classe dos streptomicetos são conhecidas por produzirem uma grande variedade de metabólitos secundários dentre eles antibióticos e antitumorais. Por isso é de grande interesse aumentar os níveis de produção desses... more
RESUMO As bactérias da classe dos streptomicetos são conhecidas por produzirem uma grande variedade de metabólitos secundários dentre eles antibióticos e antitumorais. Por isso é de grande interesse aumentar os níveis de produção desses metabólitos. Os metabólitos secundários são sintetizados por rotas biosintéticas específicas, mas os precursores e co-fatores envolvidos nessas rotas são provenientes do metabolismo primário. O aumento no nível de produção de antibióticos em streptomicetos geralmente requer modificações do metabolismo primário, modificações estas que podem ser proposta por engenharia metabólica e obtidas por engenharia genética. Neste trabalho, através de simulações do modelo metabólico proposto, será mostrado como a regulação da expressão genética de genes envolvidos na biosíntese de ácidos graxos podem interferir nos níveis de produção de cosmomicina na cepa de Streptomyces olindensis ICB20.
Some of the ideas presented at the panel discussion on engineering aspects of plant cell culture are brought together, with special emphasis on mass transfer problems and on the release of intracellular products by permeabilized cells.
Research Interests: Biology and Intracellular
ABSTRACT The information needed for the biotic activities of an organism is stored in a coded form in its DNA. This code is universal for all organisms and uses three units called nucleotides, each of which can take one of four possible... more
ABSTRACT The information needed for the biotic activities of an organism is stored in a coded form in its DNA. This code is universal for all organisms and uses three units called nucleotides, each of which can take one of four possible values to code for twenty different amino acids. Thus it is a mapping from N3 to P, where N is the set of nucleotides and P is the set of amino acids. The genetic code has been studied from the points of view of coding theory and information theory. Here we study it from the point of view of switching theory where it is considered as a logic function on a finite field and represented by its Reed-Muller expansion. We first present the genetic code, then develop its Reed-Muller expansion. Potential applications for this approach are also discussed.
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Cell immobilisation in pre-formed carriers involves passive/natural immobilisation usually in situ in the bioreactors or in the culture environment. Numerous inorganic and organic materials have been used as pre-formed carriers:... more
Cell immobilisation in pre-formed carriers involves passive/natural immobilisation usually in situ in the bioreactors or in the culture environment. Numerous inorganic and organic materials have been used as pre-formed carriers: reticulated polyurethane and polyvinyl formal foam, other polymers, plastics, stainless steel, ceramic, glass, synthetic (ion exchange) resins, activated charcoal, aluminium oxide, diatomaceous earth, sand, cellulose, lignocellulose, cellulose acetate, and others. In this chapter however, only polyurethane foam, stainless steel knitted mesh, ceramic, glass and cellulose will be considered.