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In this study, we isolated Shewanella putrefaciens from shellfish and determined the optimum growth conditions of the isolates. S. putrefaciens is Gram-negative marine bacterium which is able to produce hydrogen sulfide from thiosulfate. Initially, the isolation of S. putrefaciens was carried out by obtaining black colonies on spreadplated LB agar supplemented with ferrous sulfate and sodium thiosulfate after incubation for 24hr. All black colonies were tested for
their catalase activity and examined Gram-staining. Subsequently catalase positive and Gram-negative colonies were confirmed by PCR assays. The 16S rRNA gene and gyrB gene were used as S. putrefaciens-specific PCR primers. From three species of shellfish – oyster, short-neck clam and mussel samples tested, a total of 27 strains of S. putrefaciens were isolated and ten of them were tested to optimum growth conditions. To determine the optimum growth
conditions, we selected the range of temperature (4, 25, 30, 37 and 42℃), pH (3, 4, 5, 6, 7, 8, and 9) and NaCl concentration (0, 0.085, 0.25, 0.5, 0.7, and 1M). According to our results, all isolates grew optimally at 25℃, pH 7.0 and 0.085 M NaCl concentration.