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Determination of conductivity of bacteria by using cross-flow filtration
Mälardalen University, Department of Biology and Chemical Engineering.
Royal Institute of Technology, Sweden.
Mälardalen University, Department of Mathematics and Physics.
Mälardalen University, Department of Biology and Chemical Engineering.
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2006 (English)In: Biotechnology letters, ISSN 0141-5492, E-ISSN 1573-6776, Vol. 28, no 8, 601-603 p.Article in journal (Refereed) Published
Abstract [en]

An important property of the bacterial surface is its conductivity. To obtain reliable conductivity values, it is essential to handle the cells as gently as possible during the measurement procedure. We have developed a method where a standard conductivity meter is used in combination with cross-flow filtration, thus avoiding repeated centrifugation and resuspension. With this method, the conductivity of Bacillus subtilis was determined to be 7000 mu S/cm, which is a deviation from previously published data by almost an order of a magnitude.

Place, publisher, year, edition, pages
2006. Vol. 28, no 8, 601-603 p.
Keyword [en]
Bacillus subtilis, conductivity, cross-flow filtration, isoconductance point
National Category
Industrial Biotechnology
Identifiers
URN: urn:nbn:se:mdh:diva-10541DOI: 10.1007/s10529-006-0021-8ISI: 000236846800012Scopus ID: 2-s2.0-33645876464OAI: oai:DiVA.org:mdh-10541DiVA: diva2:359177
Available from: 2010-10-26 Created: 2010-10-26 Last updated: 2015-07-08Bibliographically approved
In thesis
1. Controlled manipulation of microparticles utilizing magnetic and dielectrophoretic forces
Open this publication in new window or tab >>Controlled manipulation of microparticles utilizing magnetic and dielectrophoretic forces
2010 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents some experimental work in the area of manipulation of microparticles. Manipulation of both magnetic and non magnetic beads as well as microorganisms are addressed. The work on magnetic bead manipulation is focused on controlled transport and release, on a micrometer level, of proteins bound to the bead surface. Experimental results for protein transport and release using a method based on magnetization/demagnetization of micron-sized magnetic elements patterned on a modified chip-surface are presented. Special attention has been placed on minimizing bead-surface interactions since sticking problems have shown to be of major importance when protein-coated beads are used. The work with non-magnetic microparticles is focused on the dielectrophoretic manipulation of microorganisms. Preliminary experimental results for trapping and spatial separation of bacteria, yeast and non-magnetic beads are presented. The overall goal was to investigate the use of dielectrophoresis for the separation of sub-populations of bacteria differing in, for example, protein content. This was, however, not possible to demonstrate using our methods.Within the non-magnetic microparticle work, a method for determining the conductivity of bacteria in bulk was also developed. The method is based on the continuous lowering of medium conductivity of a bacterialsuspension while monitoring the medium and suspension conductivities.

Place, publisher, year, edition, pages
Eskilstuna: Mälardalen University, 2010
Series
Mälardalen University Press Licentiate Theses, ISSN 1651-9256 ; 123
Keyword
Dielectrophoresis, Magnetic beads, MEMS, Micro-particles, Micro-scale manipulation, Micro-system
Research subject
Biotechnology/Chemical Engineering
Identifiers
urn:nbn:se:mdh:diva-10544 (URN)978-91-86135-93-5 (ISBN)
Presentation
2010-11-15, Selandersalen, Mälardalens högskola, Eskilstuna, 10:00 (English)
Opponent
Supervisors
Available from: 2010-10-26 Created: 2010-10-26 Last updated: 2010-11-01Bibliographically approved

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CiteExportLink to record
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