Bioassay for the rapid detection of bacteriocins in fermentation broth

摘要

A bioassay for the rapid detection of bacteriocins by detecting efflux of K~+ ions from a bacteriocin-sensitive indicator strain was developed. There was a rapid increase in concentration of K~+ in the medium from approximately 1.6 to 9.5 mM when the crude bacteriocin was added to the sensitive strain. A bacteriocin activity of 8.25 AU ml~(-1) produced the lowest detectable concentration of K~+ (0.179 mM) and the smallest inhibition zone (0.4 mm). The smallest cell dry mass of the indicator strain capable of releasing a detectable level of K~+ (0.102 mM) was 0.76 mg. Detection of the bacteriocin by measuring the efflux of K~+ compares well with the conventional agar well diffusion assay. Low activities of bacteriocin and low amounts of the sensitive indicator strain biomass can be used with this bioassay.