INHIBITORY EFFECT OF COMMON ELEMENTS TOWARDS YEAST GROWTH

Abstract

The inhibitory effect towards yeast growth and fermentation of traces of copper has been recognized for many years and several studies on this subject have been made, mostly under brewery conditions. The initial aim of the present investigations was to examine this toxicity for all elements used in construction of fermentation plant, but in view of the occurrence in small quantities of less common elements in natural materials it was decided to examine the toxicity of all the common elements to yeast growth. Of 50 common elements examined by a standard growth method in a defined synthetic medium, six (cadmium, copper, silver, osmium, mercury and palladium) have been found to be extremely toxic. Eleven others are moderately toxic, but the remainder have little poisonous action towards yeast in the concentrations normally encountered in practice. The toxicity of cadmium is reduced by addition of zinc to the medium. The toxicity of the most poisonous group of elements is considerably reduced when part of the sugar of the synthetic medium is replaced by malt or molasses wort, this effect probably being due to a reduction of ionization. 1951 The Institute of Brewing & Distilling