Electro-optical properties of microbial cells as affected by acrylamide metabolism

1999

The electrooptical (EO) properties of a cell suspension and the specific respiratory activity of cells towards p-nitrophenol (PNP) were compared during PNP metabolism in Acinetobacter calcoaceticum strain A-122. The frequency dependence of the suspension's turbidity changes due to cellular orientation (orientational spectra) at frequencies of an orienting electric field of 10^10 000 kHz was determined. Orientational spectral changes observed during PNP incubation of the cells were followed over the range of 10^502 kHz. There were linear relationships between the magnitude of the EO effect at a 502-kHz frequency and the concentration of PNP over the range of 0.1^0.8 mM, and between the specific respiratory activity of the cells and the concentration of PNP over the range of 0.1^1.0 mM. The knowledge gained from these studies suggests a direct relationship between alterations in the cellular EO properties and PNP metabolism. z

Section: Resultssupporting

confidence: 58%

Comparison of the electrooptical properties and specific respiratory activity of Acinetobacter calcoaceticum A-122

1999

“…In a previous communication [3], we showed, for the ¢rst time, the feasibility of using alterations in EO characteristics, obtained for suspensions during microbial utilization of acrylamide, to determine the enzyme activity of a biocatalyst. It would appear natural that similar e¡ects, produced during the metabolism of various substrates, would also occur in cells of other microbial strains.…”

Section: Introductionmentioning

confidence: 99%

Exploitation of the electro-optical characteristics of microbial suspensions for determining p-nitrophenol and microbial degradative activity

1998

The effect of p-nitrophenol metabolism on the electrophysical properties of a microbial cell suspension of Acinetobacter calcoaceticum was investigated. The dependence of the suspension's optical density changes due to the orientation of the electric field on the frequency of an orienting electric field (orientational spectra) over the range 10^10 000 kHz was used. Upon optimization of cell culture conditions, followed by orientational spectrum measurements, it was found that the most dramatic changes in orientation spectrum associated with p-nitrophenol metabolism took place over the frequency range 10^1000 kHz. Additionally, a linear dependence of the magnitude of the electrooptical effect on p-nitrophenol concentrations of 0.1^0.8 mM was established. The minimum p-nitrophenol concentration detectable by this calibration was 0.1 mM. z

“…and the selectivity of the cellular OS changes toward acrylamide [3]. The most substantial changes were found to occur at the ¢rst ¢ve frequencies of the orienting ¢eld (10 to 1000 kHz).…”

Section: Resultsmentioning

confidence: 93%

“…The attraction of EO analysis for monitoring microbial amidase activity was ¢rst reported in a previous paper [3], as were the basic principles of EO analysis and its applicability for studying enzymic processes in microbial suspensions. The aim of this study was to explore the e¡ect of microbial amidase activity on the EO properties of cells during batch culture on various substrates.…”

Section: Introductionmentioning

confidence: 99%

Utilisation of an electro-optical method to investigate the amidase activity of microbial cells

1998

The electro-optical (EO) properties of a microbial cell suspension of Brevibacterium sp. strain 13 PA were examined during acrylamide and acrylic acid metabolism and during culture of cells in a mineral medium without added carbon sources. The dependence of the suspension turbidity changes due to cellular orientation on the frequency of an orienting electric field (orientational spectra, OSs) over the range of 10^10000 kHz were used. Alterations in the OSs, depending on cellular amidase activity, were recorded during growth with acrylamide as the role source of carbon. However, no amidase activity was observed in cells growing with acrylic acid as the sole carbon source. Growth on the carbon-free mineral medium resulted in a reduction in amidase activity. It is apparent that the OS changes reflect the corresponding changes in cell polarisability, which may be associated with acrylamide hydrolysis. The data generated from these studies can be taken as a basis for the EO determination of the enzyme activity of microbial biocatalysts. z 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V.