Shewanella pealeana sp nov., a member of the microbial community associated with the accessory nidamental gland of the squid Loligo pealei

A new, mesophillic, facultatively anaerobic, psychrotolerant bacterium, str ain ANG-SQ1(T) (T = type strain), was isolated from a microbial community c olonizing the accessory nidamental gland of the squid Loligo pealei. It was selected from the community on the basis of its ability to reduce elementa l sulfur. The cells are motile, Gram-negative rods (2.0-3.0 mu m long, 0.4- 0.6 mu m wide). ANG-SQ1T grows optimally over the temperature range of 25-3 0 degrees C and a ph range of 6.5-7.5 degrees C in media containing 0.5 M N aCl. 16S rRNA sequence analysis revealed that this organism belongs to the gamma-3 subclass of the Proteobacteria. The closest relative of ANG-SQ1(T) is Shewanella gelidimarina, with a 16S rRNA sequence similarity of 97.0%. G rowth occurs with glucose, lactate, acetate, pyruvate, glutamate, citrate, succinate, Casamino acids, yeast extract or peptone as sole energy source u nder aerobic conditions. The isolate grows anaerobically by the reduction o f iron, manganese, nitrate, fumarate, trimethylamine-N-oxide, thiosulfate o r elemental sulfur as terminal electron acceptor with lactate. Growth of AN G-SQ1(T) was enhanced by the addition of choline chloride to growth media l acking Casamino acids. The addition of leucine or valine also enhanced grow th in minimal growth media supplemented with choline. The results of both p henotypic and genetic characterization indicate that ANG-SQ1T is a Shewanel la species. Thus it is proposed that this new isolate be assigned to the ge nus Shewanella and that it should be named Shewanella pealeana sp. nov., in recognition of its association with L. pealei.