A study of the coloring matter produced by Conidiobolus paulus Drechsler NRRL 2648 on potato-dextrose medium led to the isolation of a new dialdehyde unsaturated metabolite, (all trans)-2,4,6,8,10,12-tetradeca-1,14-hexenedial. The structure was characterized by MS and by 1H- and 13C-NMR. The compound inhibited the growth of the Gram-positive bacterium, Bacillus cereus, and the Gram-negative bacterium, Escherichia coli (MIC values of 10 micrograms and 50 micrograms, respectively).