Quinolones from a bacterium and tyrosine metabolites from its host sponge, <e7>Suberea crebae7> from the Coral Sea <e6>Abstract.e6> A marine bacterium, identified as a pseudomonad, isolated from <e5>Suberea crebae5> Bergquist, 1995 (Porifera, Dictyoceratida, Verongida, Aplysinellidae) collected along the eastern coast of New Caledonia, gave in culture phenazine-!-carboxamide, 2-<e5>ne5>-heptylquinol-4-one, 2-<e5>ne5>-nonylquinol-4-one, 2-<e5>ne5>-(1'<e5>Ee5>-nonenyl)quinol-4-one, 3-<e5>ne5>-heptyl-3-hydroxyquinolin-2,4-dione, a <e5>Ne5>-oxide-2-<e5>ne5>-heptylquinoline derivative, and a benzyldiketopiperazine. None of these products could be detected, at the HPLC-UV sensitivity level, in the sponge extracts, which contained instead (+)-aerothionin, homoaerothionin, (+)-aeroplysinin-1, dibromo-, bromochloro-, and dichloroverongiaquinol. 2-<e5>ne5>-Heptylquinol-4-one, (+)-aeroplysinin-1, and dibromoverongiaquinol showed strong antibacterial activity in vitro. The latter also proved promising for mariculture, rivaling chloramphenicol as an antibacterial agent in cultures of <e5>Pecten maximuse5> larvae, while being nontoxic according to the <e5>Artemia salinae5> test.