Germination Inhibitor from the Cellular Slime Mould Dictyostelium discoideum

Abstract

A SPORE germination inhibitor has been separated from the cellular slime mould Dictyostelium discoideum and some of its physical and chemical properties analysed. It has been previously reported that if two species of slime mould were plated out on non-nutrient agar in the presence of Escherichia coli as the food source only one of the species would grow¹; the second species appeared to be completely inhibited. Using this method, the following hierarchy of inhibition was established: D. purpureum (No. 2) > Polysphondylium violaceum (No. 6) > D. discoideum (No. 1) > D. mucoroides (No. 2) > D. mucoroides (No. 6) > D. mucoroides (petite). This hierarchy of inhibition was attributed to the presence of an inhibitor which prevented the germination of the spores, because washing the spores with distilled water annulled the inhibition. Further studies indicated that the competition did result from an inhibitor and that this inhibitor was the same within the same species but that inhibition of growth of another genera of slime moulds occurred at a stage other than germination of spores². D. purpureum (No. 2) inhibited the growth of P. violaceum (No. 6). The restriction on growth occurred at aggregation stage; the amoebae of D. purpureum prevented the aggregation of the amoebae of P. violaceum. Similar results have been reported by others^3,4.