| Abstract |
An obligately anaerobic, mildly acidophilic, fermentative alphaproteobacterium, designated strain CS4T, was isolated from an acidic, oligotrophic (nutrient poor) poor fen located near Pineola, NC, USA. Cultures contained Gram-negative, slightly curved, non-motile, non-spore-forming, non-prosthecate rods (0.1-0.4 µm in diameter and 0.4-4 µm long, depending, in part, on the growth substrate). Growth optima were 35 °C (range 15-35 °C), pH 5.6 (range of 5.0-6.8), and with 0-50 mM added NaCl (range, 0-100 mM added NaCl). The culture fermented cellobiose, d-glucose, d-mannose, fructose, galactose, glycerol, lactose, maltose, peptone, sucrose, trehalose and xylose. Respiratory growth was not detected. Major fatty acids were C18 : 1ω7c, C19 : 0 cyclo ω8c, C14 : 0 and C16 : 0. The G+C content of the DNA was 61.9±0.3 mol%. The two most closely related species phylogenetically, Rhizomicrobium palustre A48T (AB081581) and Rhizomicrobium electricum Mfc52T (AB365487) shared 94 and 93 % SSU rRNA gene sequence identity, respectively, to that of strain CS4T. Lower SSU rRNA gene sequence identities resulted from pairwise comparisons with members of the order 'Rhizobiales'(85-88 %) or Sphingomonadales(85-86 %). These findings all support the classification of strain CS4T as representative of a novel genus, family and order of Alphaproteobacteria. The type strain of the species pineolensis within the genus Micropepsis, family Micropepsaceae and order Micropepsales is CS4T (=JCM 30711T=ATCC BAA-2724T).
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