Differentiation of the species of the genus Halothiobacillus

The properties, similarity, and distinctive features of the species of Halothiobacillus are fully discussed elsewhere (Kelly et al., 1998; Kelly and Wood, 2000; Sievert et al., 2000).

List of species of the

1. Halothiobacillus neapolitanus (Parker 1957) Kelly and Wood 2000, 515VP (Thiobacillus neapolitanus Parker 1957, 86.)

ne.a.po.li.ta'nus. L. adj. neapolitanus Neapolitan; pertaining to the seawater at Naples from which this species was probably first isolated by Nathansohn in 1902.

Small rods, 0.3-0.5 X 1.0-1.5 |m. Motile by means of a polar flagellum. Colonies grown on thiosulfate agar are small (1-2 mm), circular, convex, glistening, and whitish

Halothiobacillus yellow due to precipitated sulfur. The center of old colonies becomes pink. In static culture in liquid thiosulfate medium, sulfur and polythionates may accumulate, and the medium becomes uniformly turbid with a sulfur pellicle. Aerated cultures may show transitory accumulation of te-trathionate and trithionate. pH drops to 2.8-3.3. Chemostat cultures do not accumulate intermediates and convert thi-osulfate quantitatively to sulfate. This organism oxidizes sulfur, sulfide, thiosulfate, tetrathionate, and trithionate but

TABLE BXII.y.15. Basic characteristics of species of the genus Halothiobacillus


1. H. neapolitanus

2. H. halophilus

3. H. hydrothermalis

Mol% G + C Cell size (im) Motility Carboxysomes

Obligately chemolithoautotrophic Halotolerant Optimum NaCl (M) Maximum NaCl (M) Optimum pH pH limits

Optimum temperature, °C Nitrate reduction to N2 Growth on/oxidation of: Sulfur Thiosulfate Tetrathionate Trithionate

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