Estimating cell concentration in the presence of suspended solids: A light scatter technique

A novel sensor was developed, based on light scatter, to estimate the cell concentration in the presence of suspended solids. The light scatter properties of cells in the presence of suspended solids were investigated. Two crucial observations were made: first, that the light scatter from cells is e...

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Bibliographic Details
Published in:Biotechnology and bioengineering 1992-10, Vol.40 (8), p.875-888
Main Authors: Kennedy, M. J., Thakur, M. S., Wang, D. I. C., Stephanopoulos, Gregory N.
Format: Article
Language:English
Subjects:
Bacillus subtilis
Biological and medical sciences
Biosensors
Biotechnology
Biotechnology & Applied Microbiology
cell concentration
fermentation
Fundamental and applied biological sciences. Psychology
Life Sciences & Biomedicine
light scatter
Methods. Procedures. Technologies
Science & Technology
solid substrate
Various methods and equipments
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Summary:A novel sensor was developed, based on light scatter, to estimate the cell concentration in the presence of suspended solids. The light scatter properties of cells in the presence of suspended solids were investigated. Two crucial observations were made: first, that the light scatter from cells is essentially a linear function of cell concentration and, second, that invariant regions are present in the light scatter spectrum of cell/solid substrate mixtures. Invariant regions are wavelength intervals of the light scatter spectrum in which the light scatter reading is independent of solid substrate concentration and only a function of cell concentration. The occurrence of invariant regions is the key behavior which allowed the quantification of cell concentration in the presence of suspended solids. An algorithm was developed for the estimation, from light scatter data, of cell concentration in the presence of solid substrate. The light scatter approach was validated by comparing cell concentrations estimated by this technique to those obtained from DNA and carbon dioxide evolution rate measurements during a series of fermentations. The model system used was Bacillus subtilis var sakainensis ATCC 21394 growing on fishmeal as the sole nitrogen source. A model was developed based on the interactions of scatter and absorbance. This model reflects the hypothesis that invariant regions are caused by changes in the absorbance of the solid substrate as a function of wavelength. © 1992 John Wiley & Sons, Inc.
ISSN:0006-3592
1097-0290
DOI:10.1002/bit.260400803