Table 4.

Differential characteristics of strain RH04-3^T and its closest relatives

Characteristic	1	2	3
Geographical location	Microbial mats from a thermal aquifer bore well outflow	Siltstone from a deep terrestrial subsurface	Hot spring
Habitat	Great Artesian Basin, Australia	Tayolrsville Triassic Basin, USA	Hamam Essalhine hot spring, Tunisia
Morphology	Straight to slightly curved rod-shaped	ND	Slightly curved rod shaped
Length (μm)	2.0–5.0	2.0–5.0	3.0–6.0
Width (μm)	1.0	1.0–1.1	1.0
Gram-stain	Positive	Negative	Negative
Cell-wall ultrastructure	Negative	Positive	Positive
Temperature growth range ( °C)
Optimum	50	64	55
Range	37–55	40–65	40–60
pH growth range
Optimum	7	7.5	7
Range	5–8.5	6–7.9	5.8–8.2
NaCl growth range [% (w/v)]	0–1	0–2	0–1.5
Yeast extract requirement	+	ND	–
Utilization of electron donors with sulfate
Fructose	+	+	–
Mannose	+	ND	–
Ethanol	–	+	+
Butanol	–	ND	+
Methanol	–	+	–
Propanol	–	ND	+
Formate	–	+	+
Pyruvate	+	+	+
Substrates fermented
Fructose	–	+	–
Electron acceptors
Iron(III)	–	–	+
As(V)	–	ND	+
DNA G + C content (mol %)	52.4a	47.1b	46.9b
16S rRNA similarity to RH04-3T (%)	100	95.2	93.6

Strains: 1 strain RH04-3^T, 2 Desulfotomaculum putei (Liu et al. 1997), 3Desulfotomaculum hydrothermale (Haouari et al. 2008), + positive, − negative, ND not determined

^aDetermined by the thermal denaturation method

^bDetermined by HPLC