Disruption of an aminotransferase family gene dtlA activated the production of a novel dimeric benzoic polyene acids (BPAs), named youssoufene A1 (1), along with four new (2-5, youssoufenes B1-B4) and a known (6) monomeric BPA in the marine-derived Streptomyces youssoufiensis OUC6819. The structures of 1-5 were elucidated by extensive spectroscopic and computational approaches. Youssoufene A1 (1) exhibited notably increased growth inhibition (MIC = 12.5 μg/mL) against multidrug resistant Enterococcus faecalis compared to monomeric structures (2-6).