A plant-sap-derived preparation containing bi- and tervalent ferrate anions was tested on growth, respiration on glucose, and membrane transport of 6-deoxy-D-glucose (6-dGlc) and 2-aminoisobutyric acid (Aib) in several yeast species, Saccharomyces cerevisiae, Schizosaccharomyces pombe, Lodderomyces elongisporus, Rhodotorula gracilis, and Dipodascus magnusii. Growth was enhanced by as much as 65%, respiration was not affected significantly except for a decrease in R. gracilis, transport of 6-dGlc was not affected while that of Aib was increased by up to 45% in R. gracilis and up to 27% in L. elongisporus.