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

1 Center for Great Lakes Studies, University of Wisconsin-Milwaukee, Milwaukee, WI 53204, USA 2 Istituto di Scienze Tossicogiche Ingienstiche e Ambientali, University of Urbino, 61029 Urbino, Italy 3 Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA 4 Department of Civil Engineering, Northwestern University, Evanston, IL 60208, USA 5 Department of Molecular Genetics, Forsyth Institute, Boston, MA 02115, USA 6 Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Mascheroder Weg 1b, D-38124 Braunschweig, Germany 7 Jet Propulsion Laboratories, California Polytechnic Institute, Pasadena, CA 91109, USA Author for correspondence: Michael R. Leonardo. Tel: +1 205 348 5191. Fax: +1 205 348 1403. e-mail: mleonard{at}biology.as.ua.edu ABSTRACT A new, mesophillic, facultatively anaerobic, psychrotolerant bacterium, strain ANG-SQ1 T (T=type strain), was isolated from a microbial community colonizing the accessory nidamental gland of the squid Loligo pealei . It was selected from the community on the basis of its ability to reduce elemental sulfur. The cells are motile, Gram-negative rods (2·0–3·0 µm long, 0·4–0·6 µm wide). ANG-SQ1 T grows optimally over the temperature range of 25–30 °C and a pH range of 6·5–7·5 °C in media containing 0·5 M NaCl. 16S rRNA sequence analysis revealed that this organism belongs to the -3 subclass of the Proteobacteria . The closest relative of ANG-SQ1 T is Shewanella gelidimarina , with a 16S rRNA sequence similarity of 97·0%. Growth occurs with glucose, lactate, acetate, pyruvate, glutamate, citrate, succinate, Casamino acids, yeast extract or peptone as sole energy source under aerobic conditions. The isolate grows anaerobically by the reduction of iron, manganese, nitrate, fumarate, trimethylamine- N -oxide, thiosulfate or elemental sulfur as terminal electron acceptor with lactate. Growth of ANG-SQ1 T was enhanced by the addition of choline chloride to growth media lacking Casamino acids. The addition of leucine or valine also enhanced growth in minimal growth media supplemented with choline. The results of both phenotypic and genetic characterization indicate that ANG-SQ1 T is a Shewanella species. Thus it is proposed that this new isolate be assigned to the genus Shewanella and that it should be named Shewanella pealeana sp. nov., in recognition of its association with L. pealei . Key Words: Shewanella pealeana • Loligo pealei • sulfur reducer • choline The GenBank accession numb