Optimisation of a rapid bioassay for nisin utilising potassium efflux from sensitivePediococcus sp. cells

Abstract

SUMMARYAddition of nisin to a K+-loaded, metabolising suspension of Pediococcus sp resulted in K + efflux into the medium. The total K + efflux was proportional to the logarithm of the nisin activity with a MEC of 0.7 IUml "~ and resulted in total loss of cellular K + at 4-5 IUml nisin. Conditions were optimised for the use of K + efflux measurements as a rapid nisin bioassay using a combination of factorial and sequential simplex proeedures. A nisin assay based on K + efflux measurements was used to follow the course of a nisin-producing fermentation.