Table 3.

Phenotypic comparison of Neptunomonas strains and related organisms

CharacteristicNeptunomonasOceanospirilluma O. japonicumO. kriegiiMarinobacterium
Cell shapeStraight rodsSpirillaSpirillaStraight and curved rodsStraight rods
Motility+b ++++
Flagellar arrangementSingle polarBipolar tuftsBipolar tuftsSingle polarSingle polar
Cell diam (μm)0.7–0.90.3–1.20.8–1.40.8–1.20.5–0.7
PHB accumulationc ++++
Na+ requirement+++++
NO3 reduced to NO2 D
Oxidase activity+++++
Catalase activity+DW or −NR+
Enzyme activities
Acid produced from carbohydrates+
Carbohydrates fermented+
Temp (°C)4–302–4110–4320–354–41
Water-soluble brown pigment+DNRNR
DNA G+C content (mol%)4645–5045NR54.9
  • a The data include data for the members of the genus Oceanospirillum described by Krieg (23), except that data for O. japonicum are given separately because there is uncertainty concerning whether this organism should be included in the genus (34).

  • b +, positive; −, negative; D, results depend on the species or strain used; W, weak; NR, not reported.

  • c PHB, poly-β-hydroxybutyrate.