Table 1.

Respiration rates and anoxic survival potential for representatives of the vacuolate sulfur bacteria

Bacterium	NO−3 stored?: (molarity) respiration rate (nmol NO−3 min−1 mg−1 protein)	Anoxic survival on stored NO−3	Respire O2?	Cell diameter (μm); % vacuole
Thiomargarita namibiensis a	Yes (0.1–0.8 M); ~1	15–120 days	Yes	100–750; 98%
Thioploca araucae & Thioploca chileae b	Yes (0.16–0.5 M); ~1	8–25 days	No	12–42; 90%
Beggiatoa sp. ‘Monterey Canyon’c	Yes (0.16 M); 1–4	1–4 days	Yes	65–85; 80%
Vacuolate-Attached Filaments (VAF)	No d	Not on NO−3 1–16 min Oe2	Assumedf, Not tested	10–112d; 89–94%

Major finding of the study and a key difference between VAF and other vacuolate sulfur-oxidizers is indicated in bold

^aSchulz et al. 1999; Schulz and de Beer 2002

^bFossing et al. 1995; Otte et al. 1999; data reported collectively for both species

^cMcHatton 1998; McHatton et al. 1996

^dKalanetra et al. 2004; this study

^eCalculated over temperature range of 4–25°C assuming cytoplasm: vacuole ratio shown in column 5. O₂ respiration rate (8–25 nmol min⁻¹ mg⁻¹ protein) estimated based on McHatton (1998). Q₁₀ for respiration taken as 2.0. Cytoplasm assumed to be 80% water + 20% dry matter and protein assumed to comprise 50% of cellular dry matter. Comparable rate (13 nmol min⁻¹ mg⁻¹ protein) extrapolated for T. namibiensis from data of Schulz and de Beer, 2002. Vacuolar O₂ concentration assumed at 240 μM

^fNot yet confirmed by respirometry but most logical alternative to nitrate respiration