Shear stress effects on plant cell suspension cultures in a rotating wall vessel bioreactor

Journal of Industrial Microbiology and Biotechnology (Impact Factor: 2.51). 12/1998; 22(1):44-47. DOI: 10.1038/sj.jim.2900600

ABSTRACT A rotating wall vessel, designed for growth of mammalian cells under microgravity, was used to study shear effects on Taxus cuspidata plant suspension cell cultures. Shear stress, as quantified by defined shear fields of Couette viscometers, improved specific
cell growth rates and was detrimental to volumetric product formation rates.

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    ABSTRACT: Generation of active oxidative species induced by shear stress in suspension cultures of Taxus cuspidata was investigated in a Couette-type shear reactor. It was found that T. cuspidata cells respond to a shear rate of 95 s(-)(1) with oxidative bursts. Their triphasic characteristics in 6 h were similar in both intracellular H(2)O(2) production and extracellular O(2)(-)( )(*) production. Additionally, inhibition studies with diphenylene iodonium and azide suggested that the key enzyme responsible for oxidative bursts under the shear rate of 95 s(-)(1) is primarily NADPH oxidase and the contribution of peroxidase for oxidative bursts was less. Investigation of the relationship between active oxidative species and defense responses induced by the shear stress indicated that the O(2)(-)( )(*) burst may account for the change of membrane permeability, and the H(2)O(2) burst plays an important role in inducing secondary metabolites such as the activation of phenylalanine ammonia lyase enzyme and phenolic accumulation. Furthermore, oxidative bursts elicited by the shear rate of 95 s(-)(1) were suppressed by treatment with suramin, nifedipine, and neomycin prior to the shear stress treatment, suggesting that G-protein, Ca(2+) channel, and phospholipase C are involved in the signal pathway for oxidative bursts induced by the shear stress. A model is proposed to explain the oxidative burst in cultured T. cuspidata cells challenged with the shear stress.
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    ABSTRACT: The effect of steady shear stress on somatic embryos were investigated in a flow chamber and evaluated at different time intervals using microscopy technique. The development of meristematic cell clusters, i.e. the immature embryos, into a polarized somatic embryo, and the effect on the localization of the suspensor cells that form during development of the immature embryos, were studied as a function of shear stresses. With the distribution and growth rate of the meristematic and suspensor cells, the effect of stress on the embryo development was established. Furthermore, the effect of shear stress on the cells at molecular level, the reaction of integrin-like proteins, the production of reactive oxygen species and the pore size of the cell walls involved in the shear stress responses, were investigated with molecular techniques. In general, shear stress inhibits meristematic cells growth. Meristematic cells grow fastest at shear rate of 86 s-1 among all the tested shear stress conditions. By combining the results of meristematic cells growth and suspensor cells formation, it suggests that there is a critical shear rate between 86 and 140 s-1, at which no suspensor cells form. The unidirectional flow with different shear stresses helps the polarized growth and the unidirectional alignment of suspensor cells. Reactive oxygen species and integrin-like protein are detected in the stressed cells as cellular responses to shear stresses. By monitoring the pore size and uptake time of cells to macromolecules with solute-exclusive experiments, it suggests that the stressed cells expedite the response to plasmolyzing components that are used to induce maturation treatment thus affect the response to maturation stimuli.
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    ABSTRACT: Suspension cultures of Taxus canadensis were elicited with methyl jasmonate (MJ) under defined headspace ethylene concentrations. Kinetic studies of growth, nutrient consumption, pH variation, and paclitaxel accumulation were conducted in batch cultures and semicontinuous culture with total cell recycle. A dramatic increase of paclitaxel was obtained when the cultures were elicited with 100 microM MJ, but cell growth was thereby arrested. Supplementation of acetyl-CoA and MJ to the culture proved to be another way to improve paclitaxel yields. Using semicontinuous culture with total cell recycle, paclitaxel accumulation was increased by a factor of 4.0 relative to that in the batch culture during 35 days of cultivation.
    Biotechnology Progress 12/1999; 15(6):1072-7. DOI:10.1021/bp990098p · 1.88 Impact Factor