INORGANIC PYROPHOSPHATASE-BASED DETECTION SYSTEMS .2. DETECTION AND QUANTIFICATION OF CELL-LYSIS AND CELL-LYSING ACTIVITY

A novel technique, useful for detection of cell lysis and cell-lysing activity, has been developed. The method can be used for detection of cell lysis, both induced and natural, in all types of cells. The techn ique can be used for detection and quantification of all types of cell -lysing activities, e.g., cell wall hydrolases, toxicants, phospholipa ses, and antibiotics. The method relies on the detection, by a very se nsitive enzymatic luminometric inorganic pyrophosphate detection assay (ELIDA; P. Nyren and A. Lundin (1985) Anal. Biochem. 151, 504-509) of an enzyme, inorganic pyrophosphatase, which is constitutively express ed in all cells. The fraction of lysed cells in a sample can be assess ed by determining the activity in the absence and in the presence of t otal lysing activity. The technique was used for determination of the effect of storage conditions on the intactness of two different cells, Micrococcus luteticus and Saccharomyces cerevisiae. In a model system , the approach was also used for detection of cell-lysing activity. Th e activity of a cell wall hydrolase (lysozyme) and a surfactant (Trito n X-100) was quantified. M. luteticus cells were incubated with a spec ific buffer containing the lysing activity and inorganic pyrophosphate . The amount of unhydrolyzed PPi was determined by the ELIDA. The amou nt of PPi hydrolyzed was proportional to the amount of lysozyme presen t. The sensitivity of the assay was dependent on several factors, such as amount of cells used, incubation time, and incubation temperature. Lysozyme at concentrations below 5 ng/ml (<50 pg) could be detected. The possibility of using the approach for detection of other types of cell-lysing activities is discussed. Possible applications for the app roach in a wide variety of areas such as clinical laboratories, food a nd dairy industries, and the pharmaceutical industry are also discusse d. (C) 1994 Academic Press, Inc.