Thermocrinis minervae sp. nov., a hydrogen- and sulfur-oxidizing, thermophilic member of the Aquificales from a Costa Rican terrestrial hot spring

1 Department of Biology, Portland State University, PO Box 751, Portland, OR 97207-0751, USA 2 Departament de Biologia Marina i Oceanografia, Institut de Ciències del Mar-CMIMA, CSIC, Passeig Marítim de la Barceloneta 37–49, E-08003 Barcelona, Catalunya, Spain 3 Department of Microbiology, College of Biological Science, University of Guelph, Guelph, ON N1G 2W1, Canada Correspondence Anna-Louise Reysenbach reysenbacha{at}pdx.edu A thermophilic bacterium, designated strain CR11 T , was isolated from a filamentous sample collected from a terrestrial hot spring on the south-western foothills of the Rincón volcano in Costa Rica. The Gram-negative cells are approximately 2.4–3.9 µm long and 0.5–0.6 µm wide and are motile rods with polar flagella. Strain CR11 T grows between 65 and 85 °C (optimum 75 °C, doubling time 4.5 h) and between pH 4.8 and 7.8 (optimum pH 5.9–6.5). The isolate grows chemolithotrophically with S 0 , or H 2 as the electron donor and with O 2 (up to 16 %, v/v) as the sole electron acceptor. The isolate can grow on mannose, glucose, maltose, succinate, peptone, Casamino acids, starch, citrate and yeast extract in the presence of oxygen (4 %) and S 0 . Growth occurs only at NaCl concentrations below 0.4 % (w/v). The G+C content of strain CR11 T is 40.3 mol%. Phylogenetic analysis of the 16S rRNA gene sequence places the strain as a close relative of Thermocrinis ruber OC 1/4 T (95.7 % sequence similarity). Based on phylogenetic and physiological characteristics, we propose the name Thermocrinis minervae sp. nov., with CR11 T (=DSM 19557 T =ATCC BAA-1533 T ) as the type strain. The GenBank/EMBL/DDBJ accession number for the partial 16S rRNA gene sequence of strain CR11 T is AM260555 . Graphs showing the effect of temperature and pH on growth of strain CR11 T are available as supplementary material with the online version of this paper.