Genome mining of Fulvivirga sp. W222 revealed a desferrioxamine-like biosynthetic gene cluster containing an unknown gene fulF that is conserved in many Bacteroidetes species. A series of primary amine-acylated desferrioxamine G1 analogues, fulvivirgamides, were identified, and fulvivirgamides A2, B2, B3, and B4 (1-4) were purified and characterized. The function of FulF, which is a novel acyltransferase for the acylation of the primary amine of Desferrioxamine G1, was verified by heterologous expression and feeding experiments.