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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Biotechnology letters 12 (1990), S. 793-798 
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The most direct approach to enhancing the volumetric yield of secondary metabolites in plant tissue cultures is to operate the culture under high cell density. In this study, a cell suspension ofAnchusa officinalis was cultivated using a semi-continuous perfusion technique, i.e. batch cultivation with intermittent medium exchange. Using a perfusion medium containing sucrose concentration which was two times that in the normal growth medium, the final cell density and the final product concentration were increased by more than 2-fold compared with a batch culture without medium exchange. The high cell density obtained from the semi-continuous perfusion culture can be explained by the prevention of nutrient depletion, removal of toxic by-products, as well as the control of cell size by virtue of the high sugar medium osmolarity.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biotechnology letters 13 (1991), S. 889-892 
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary In this study, a perfusion fermentation ofAnchusa officinalis was carried out in a stirred tank bioreactor integrated with an internal cross-flow filter. Bubble-free aeration via microporous membrane fibers was used to provide oxygen. A two-stage culture was successfully conducted in this reactor without filter fouling. In a 17 day fermentation, a cell density of 26 g dw/I and a rosmarinic acid productivity of 94 mg/l day were achieved. This productivity is three times that obtained in a batch culture.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Biotechnology techniques 9 (1995), S. 259-264 
    ISSN: 1573-6784
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The effect of agitation and aeration on filtration of Anchusa officinalis culture in a stirred tank bioreactor integrated with an internal filter unit was investigated. Increases in suction head of the pump that drove the filtration process were measured at impeller speeds of 100 and 200 rpm. Surprisingly, suction head attained at 200 rpm was about 40% higher than at 100 rpm. Direct observation of the cake deposition process in the reactor using a dilute cell suspension revealed that the filter cake formed at 100 rpm was thicker, but less compact. Aeration at 0.4 vvm was shown to have little effect on the filtration rate, since the bulk fluid flow was dominated by the impeller hydrodynamics. The initial flux can be recovered by filter backwashing with compressed air at a flow rate of 0.6 vvm for a duration of 5 minutes.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 50 (1997), S. 91-95 
    ISSN: 1573-5044
    Keywords: neem ; somatic embryo ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A modified culture protocol has been developed for the induction of somatic embryogenesis in Azadirachta indica (neem). Embryogenic calluses were initiated from cotyledons or hypocotyls using a Murashige and Skoog (MS) agar medium supplemented with 0.5 mg l−1 α-napthaleneacetic acid (NAA), 1 mg l−1 6-benzylaminopurine (BA), 1 g l−1 casein hydrolysate, and 50 g l−1 sucrose. The calluses, when transferred to a liquid medium similar to the agar medium but with NAA replaced by 0.5 mg l−1 indole-3-acetic acid (IAA), formed globular structures which further developed a rudimentary root, after 4 to 5 weeks incubation. Subsequently, these highly differentiated tissues when transferred into a hormone-free MS medium containing 1 g l−1 casein hydrolysate and 50 g l−1 sucrose, active embryo masses started to appear after 1 to 2 weeks. The embryo production was found to improve more than 2 fold by adding 0.2 mg l−1 zeatin to the medium.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 884-890 
    ISSN: 0006-3592
    Keywords: perfusion culture ; Anchusa officinalis ; rosmarinic acid ; medium exchange ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The production of an intracellular secondary metabolite rosmarinic acid (RA) by plant cell suspensions of Anchusa officinalis cultivated with intermittent medium exchange is investigated. Initially, a two-stage perfusion culture method was employed. After being cultured in the batch mode for ca. 6 days in B5 medium plus 3% sucrose, 1 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D), and 0.1 mg/L kinetin (2,4-D B5 medium), Anchusa culture was cultivated to high cell density by perfusion during the growth stage using a hormone-free Gamborg B5 medium supplemented with 6% sucrose. This was followed by a production stage, in which a complete medium exchange into B5 medium plus 3% sucrose and 0.25 mg/L naphthleneacetic acid (NAA) was conducted. The two-stage perfusion culture had a higher maximum culture RA concentration but a lower RA content per cell than the batch stock culture maintained in the 2,4-D B5 medium. Higher culture RA concentration was due primarily to high cell density. The high packed cell volume, however, seemed to reduce the synergistic effect of NAA on RA synthesis. Subsequently, a single-stage perfusion culture method was investigated. The best result was obtained by growing the culture in the batch mode for ca. 10 days using B5 medium supplemented with 3% sucrose and 0.25 mg/L NAA, followed by perfusing the culture with B5 medium plus 6% sucrose and 0.25 mg/L NAA at a constant perfusion rate of 0.1/day. A maximum cell dry weight of 35 g/L and a RA concentration of almost 4 g/L were achieved. This is the highest RA concentration ever reported in the Anchusa culture. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Biotechnology letters 15 (1993), S. 1035-1038 
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary High cell density and rosmarinic acid (RA) productivity have been achieved by applying periodic culture perfusion to the Anchusa officinalis cell suspension. In this study, the effect of inoculum size on cell growth and RA productivity in the perfused Anchusa culture was investigated. Experimental results showed that RA productivity increased with the inoculum size, up to 4 g dry weight/L. Further increases in the inoculum size did not yield a higher RA productivity regardless of culture perfusion. Moreover, the maximum cell concentration was not affected by the inoculum sizes, from 1 to 11 g dry weight/L. Cell crowding, indicated by high culture packed cell volumes, is believed to be the predominant cause of low productivity in perfused cultures with high inoculum sizes.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 31 (1988), S. 750-754 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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