Three antibiotics were isolated from a CH2Cl2 extract of the liquid culture of Pseudomonas fluorescens strain PFM2. Two of the antibiotics were identified as 2,4-diacetylphloroglucinol and pyoluterin. The structure elucidation, absolute stereochemistry, synthesis, and biological activities of the new antibiotic (+)-(S)- dihydroaeruginoic acid [1] are reported.