The correlation between the consumption of amino acids and the production of the polypeptide antibiotic gallidermin by Staphylococcus gallinarum Tu 3928 was investigated by on-line determination of amino acids and pulse experiments. A prolonged production phase together with an increase in gallidermin formation of about 25% was obtained during pulse and fed-batch experiments with the amino acids glutamic acid, glycine, serine and threonine.