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RISS 인기검색어
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- 저자 : Rami Reddy Vennapusa (검색결과 2 건)
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Rami Reddy Vennapusa,Muhammad Aasim,Rosa Cabrera,Marcelo Fernandez-Lahore 한국생물공학회 2009 Biotechnology and Bioprocess Engineering Vol.14 No.4
Cell-to-support interaction and cell-to-cell agglomeration phenomena have been studied in a model system composed of intact yeast cells and Chelating-StreamlineTM adsorbents. Biomass components and beaded adsorbents were mainly characterized by contact angle determinations with three diagnostic liquids. Complementarily, zeta potential measurements were performed. These experimental values were employed to calculate free energy of interaction versus distance profiles in aqueous media. The effect of immobilized metal-ion type and buffer pH on the interaction energy was evaluated. Calculations indicated that moderate interaction between cell particles and adsorbent beads can develop due to the presence of Cu2+ ions onto the solid phase. The strength of interaction increased with buffer pH, within the range 6.0 to 8.3 e.g. secondary energy pockets increased from |15| to |60| kT. Cell-to-cell secondary energy minimum was ≥ |14| kT showing low-to-moderate tendencies to aggregate, particularly at pH ≥ 8. Extended DLVO predictions were generally confirmed by biomass deposition experiments. However, an exception was found when working with immobilized Cu2+ at pH 8 since yeast cells were able to sequestrate such immobilized ions. Therefore, lower-than-expected values for the depositions coefficient (α) were observed. Understanding biomass attachment onto Chelating supports can help in better design and operate expanded bed adsorption of bioproducts.
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Nadia Naz,Roy N. Dsouza,Vikas Yelemane,Rami Reddy Vennapusa,Martin Kangwa,Marcelo Fernández-Lahore 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.3
The cell surface characteristics of a methylotrophic wild-type strain of yeast, Hansenula polymorpha, was investigated at different growth stages (early log, late log, stationary and death) of the biomass under different conditions (low and high salt in intact and disrupted forms) using extended DLVO theory. Biomass was characterized by contact angle measurements as well as zeta potential determinations. These measurements were used to describe the hydrophobic, polar, and electrostatic behavior of the biomass in its growth stages. Consequently, interaction free energy vs. distance profiles of the biomass with anionexchange and HIC adsorbents were conveniently generated. A strong interaction was calculated between cells and the adsorbents in the stationary and death phases of the biomass illustrated by the striking correlation between theoretical predictions and biomass deposition experiments. The physico-chemical properties of biomass in different growth phases have important implications for expanded bed adsorption chromatography, where unfavorable biomassadsorbent interactions adversely affect process efficiency.
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