Details
| Original language | English |
|---|---|
| Pages (from-to) | 617-625 |
| Number of pages | 9 |
| Journal | Biotechnology and Bioengineering |
| Volume | 44 |
| Issue number | 5 |
| Publication status | Published - 20 Aug 1994 |
| Externally published | Yes |
Abstract
Polarographic microcoaxial needle electrodes were used to measure internal profiles of dissolved oxygen tension (Po2) within single Ca‐alginate beads of different diameter containing entrapped cells of Saccharomyces cerevisiae. For the investigations, single beads coming from variable growing conditions and distinct cultivation stages were fixed in a special holding device. In dependence on microbial growth steep oxygen gradients were observed. The Oxygen penetration depth at steady state lay between 50 and 100 μm. After 8 h of cultivation time, the anaerobic space within the beads (ϕ 2 mm; cultivation in a packed bed reactor) is beginning at ∼ 130 μm, whereas the anaerobic space within the beads (ϕ 2 mm) coming from the shaker flask culture is located ∼440 μm below the bead surface. Surprisingly, steep gradients were also observed, when recording profiles from cell‐free Ca‐alginate beads of different diameter and alginate concentrations. The steep oxygen gradients apparently had to be interpreted as pseudo‐Po2‐gradients. These results were borne by several effects, such as formation of artifacts and diffusion barriers in front of the electrode tip or oxygen “availability” at the tip and consumption of oxygen by the electrode itself. These phenomena could be documented by microscopic observation and photography. Thus, to obtain real Po2‐profiles it is important to be exactly informed about the physical, chemical, and biological properties of the material to be investigated. Furthermore, it is necessary to apply a special stepwise puncture technique with distinct step‐in/step‐out movements of the electrode: e.g., unidirectional or contradirectional puncture techniques. © 1994 John Wiley & Sons, Inc.
Keywords
- alginate beads, artifacts, oxygen microprobe, oxygen profiles, Po‐microelectrode, Saccharomyces cerevisiae
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Biotechnology
- Chemical Engineering(all)
- Bioengineering
- Immunology and Microbiology(all)
- Applied Microbiology and Biotechnology
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In: Biotechnology and Bioengineering, Vol. 44, No. 5, 20.08.1994, p. 617-625.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Real and Pseudo Oxygen Gradients in Ca‐Alginate Beads Monitored During Polarographic Po2‐Measurements Using Pt‐Needle Microelectrodes
AU - Müller, W.
AU - Winnefeld, A.
AU - Kohls, O.
AU - Scheper, T.
AU - Zimelka, W.
AU - Baumgärtl, H.
PY - 1994/8/20
Y1 - 1994/8/20
N2 - Polarographic microcoaxial needle electrodes were used to measure internal profiles of dissolved oxygen tension (Po2) within single Ca‐alginate beads of different diameter containing entrapped cells of Saccharomyces cerevisiae. For the investigations, single beads coming from variable growing conditions and distinct cultivation stages were fixed in a special holding device. In dependence on microbial growth steep oxygen gradients were observed. The Oxygen penetration depth at steady state lay between 50 and 100 μm. After 8 h of cultivation time, the anaerobic space within the beads (ϕ 2 mm; cultivation in a packed bed reactor) is beginning at ∼ 130 μm, whereas the anaerobic space within the beads (ϕ 2 mm) coming from the shaker flask culture is located ∼440 μm below the bead surface. Surprisingly, steep gradients were also observed, when recording profiles from cell‐free Ca‐alginate beads of different diameter and alginate concentrations. The steep oxygen gradients apparently had to be interpreted as pseudo‐Po2‐gradients. These results were borne by several effects, such as formation of artifacts and diffusion barriers in front of the electrode tip or oxygen “availability” at the tip and consumption of oxygen by the electrode itself. These phenomena could be documented by microscopic observation and photography. Thus, to obtain real Po2‐profiles it is important to be exactly informed about the physical, chemical, and biological properties of the material to be investigated. Furthermore, it is necessary to apply a special stepwise puncture technique with distinct step‐in/step‐out movements of the electrode: e.g., unidirectional or contradirectional puncture techniques. © 1994 John Wiley & Sons, Inc.
AB - Polarographic microcoaxial needle electrodes were used to measure internal profiles of dissolved oxygen tension (Po2) within single Ca‐alginate beads of different diameter containing entrapped cells of Saccharomyces cerevisiae. For the investigations, single beads coming from variable growing conditions and distinct cultivation stages were fixed in a special holding device. In dependence on microbial growth steep oxygen gradients were observed. The Oxygen penetration depth at steady state lay between 50 and 100 μm. After 8 h of cultivation time, the anaerobic space within the beads (ϕ 2 mm; cultivation in a packed bed reactor) is beginning at ∼ 130 μm, whereas the anaerobic space within the beads (ϕ 2 mm) coming from the shaker flask culture is located ∼440 μm below the bead surface. Surprisingly, steep gradients were also observed, when recording profiles from cell‐free Ca‐alginate beads of different diameter and alginate concentrations. The steep oxygen gradients apparently had to be interpreted as pseudo‐Po2‐gradients. These results were borne by several effects, such as formation of artifacts and diffusion barriers in front of the electrode tip or oxygen “availability” at the tip and consumption of oxygen by the electrode itself. These phenomena could be documented by microscopic observation and photography. Thus, to obtain real Po2‐profiles it is important to be exactly informed about the physical, chemical, and biological properties of the material to be investigated. Furthermore, it is necessary to apply a special stepwise puncture technique with distinct step‐in/step‐out movements of the electrode: e.g., unidirectional or contradirectional puncture techniques. © 1994 John Wiley & Sons, Inc.
KW - alginate beads
KW - artifacts
KW - oxygen microprobe
KW - oxygen profiles
KW - Po‐microelectrode
KW - Saccharomyces cerevisiae
UR - http://www.scopus.com/inward/record.url?scp=0028485582&partnerID=8YFLogxK
U2 - 10.1002/bit.260440508
DO - 10.1002/bit.260440508
M3 - Article
AN - SCOPUS:0028485582
VL - 44
SP - 617
EP - 625
JO - Biotechnology and Bioengineering
JF - Biotechnology and Bioengineering
SN - 0006-3592
IS - 5
ER -