ABSTRACT
The method of spectrophotometric determination of cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) activity with the use of phenolphthalein as a colored reagent has been improved. This technique includes an enzymatic reaction at 40 degrees C for 60 min in 2% starch, with subsequent supplementation of the reaction mixture (0.5 ml) with the phenolphthalein reagent (3.0 ml) prepared in 0.1 M potassium carbonate buffer (pH 11.0) according to a special procedure, and measurement of the optical density of the obtained mixture at 553 nm. The activity was calculated using the exponential growth equation that connects a drop in the optical density and the degree of dilution of the enzyme. The described technique is suitable for working in a sufficiently broad range of specific activity of beta-CGTase and does not require precise adjustment of the degree of dilution of solutions analyzed.
Subject(s)
Glucosyltransferases/chemistry , Buffers , Hydrogen-Ion Concentration , Indicators and Reagents , Phenolphthalein , Photometry , TemperatureABSTRACT
Quantitative assessment, using three Pseudomonas sp. strains, of the activity of the microbial biocide Soncid 8101 demonstrated that the values of effective sublethal concentrations (L50) differed by 500% (because of individual variations in the sensitivity of the test strains). The spread of parameters of biocidal activity could be narrowed by using a mixture of microorganisms with high, medium, and weak resistance. A method for quantitative assessment of the activity of microbial biocides was proposed, based on the use of natural associations of soil bacteria.
