Luminous bacteria were isolated from invertebrates and coastal seawater samples in the summer season 2004, from Izmir Gulf in Turkey. The seawater samples were concentrated by using 0.22-mu pore-sized nitrocellulose membrane filters. The concentrated seawater samples and intestinal contents of Holothuria tubulosa were inoculated on Seawater Complete (SWC) and BOSS media. The agar plates were incubated at 25 degrees C for 48 h. After incubation, bioluminescent bacteria were isolated in a dark room, then purified and stored on a suitable medium. Bioluminescent isolates were identified with a polyphasic approach by using morphological, cultural, biochemical and molecular characteristics, in addition to 16SrDNA sequencing. Finally, the bioluminescent marine bacteria isolated from intestinal contents of H. tubulosa and seawater samples were identified as Vibrio harveyi TEM S1 and TEM O5 strains, respectively.