Stygiolobus azoricus gen. nov., sp. nov. Represents a Novel Genus of Anaerobic, Extremely Thermoacidophilic Archaebacteria of the Order Sulfolobales

Abstract

On the basis of three isolates (strains FC6T [T = type strain], FC4, and RG1) of extremely thermophilic chemolithoautotrophic archaebacteria obtained from solfataric fields on Sao Miguel Island, Azores, the new genus Stygiolobus is described. These isolates grow obligately chemolithotrophically by reduction of So with H, (H,-SO lithotrophy) and are the first strictly anaerobic members of the order Sulfolobales. With a DNA G+C content of 38 mol%, the Stygiolobus isolates resemble Sulfolobus spp., which, however, are faculatively organotrophic and aerobic So oxidizers. The new isolates are also distinct from Acidianus spp., which resemble Stygiolobus by growing by H,-SO lithotrophy. However, Acidianus spp. can also grow aerobically by So oxidation and have G+C contents of 31 mol%. At this time, only one species of the genus Stygiolobus is known, Stygiolobus uzoricus sp. nov.; the type strain of S. uzoricus is strain FC6 (= DSM 6296).The thermophilic sulfur-metabolizing archaea (archaebacteria) (66; for reviews, see references 56 and 62) that occur in acid solfataric fields comprise the following three groups: (i) the order Sulfolobales (29,59; for a review, see reference 51); (ii) the order Thermoproteales (24, 70; for a review, see reference 22); and (iii) the genus Thermoplasma (9, 46, 55; for reviews, see references 50 and 62), which because of its isolated phylogenetic position probably represents an order that is distantly related to the methanogens (65, 67). The following four genera have been validly assigned to the order Sulfolobales: (i) the genus Sulfolobus (7, 551, which is the type genus and currently includes the species Sulfolobus acidocaldarius (type species) (7,55), Sulfolobus solfataricus (23, 71), and Sulfolobus shibatae (16); (ii) the genus Metallosphaera, with one species, Metallosphaera sedula (18,29); (iii) the genus Acidianus (47), which includes the species Acidianus infernus (type species) and Acidianus brierleyi (5,47,71); and (iv) the genus Desulfurolobus, with the single species Desulfurolobus ambivalens (26,72). Suifolobus and Metallosphaera spp. are aerobic or facultatively anaerobic, facultatively organotrophic chemolithoautotrophs that are capable of oxidizing molecular sulfur, sulfide, or tetrathionate to H, SO, (6, 8,18,54,68) and have relatively high DNA G + C contents (about 35 to 45 mol%).In contrast, Acidianus and Desulfurolobus spp. are facultatively anaerobic organisms that grow by either oxidation or reduction of elemental sulfur, forming H,SO, and H,S, respectively (52). Relatively low G+C contents (about 31 mol%) are also characteristic of these organisms. The features that distinguish the genera Acidianus and Desulfurolobus are not well defined. In fact, D . ambivalens closely resembles A. infernus in both phenotype and genotype (20,47,72). A level of DNA homology of about 60% with A . infernus (20; this paper) indicates (45) that D. ambivalens is another species of the genus Acidianus.As inferred from immunochemical features of their DNAdependent RNA polymerases, all of...

Study of the distribution of autotrophic CO2 fixation cycles in Crenarchaeota

“…However, some autotrophic members of the Sulfolobales (Acidianus sp., Stygiolobus azoricus) are capable of growth under strictly anaerobic conditions (Segerer et al, 1985(Segerer et al, , 1986(Segerer et al, , 1991Huber & Stetter, 2001). All sequenced Sulfolobales contain putative pyruvate synthase, pyruvate : water dikinase and PEP carboxylase genes required for the dicarboxylate/4-hydroxybutyrate cycle (Auernik et al, 2008;Chen et al, 2005;Kawarabayasi et al, 2001;She et al, 2001;Reno et al, 2009).…”

Life in hot springs and hydrothermal vents

“…Figures 3, 4). The cocci may be more or less regularly or highly irregularly in shape, depending on the organism (Stetter et ai, 1990; Table II 1989b; Segerer and Stetter, 1991b). There are some exceptional morphological types: (a) Pyrodictium cells possess ultraflat areas and are connected by a network of hollow proteinaceous fibres of yet unknown function endospores are formed by the hyperthermophiles known to date.…”

“…The hyperthermophilic methanogens (e.g., Figure 1) and Stygiolobus azoricus (Figure 3) are probably highly specialized, growing obiligately autotrophically by only one means of energy yielding reaction (methanogenesis and H 2 -S° lithoautotrophy, respectively; see below). Four types of chemolithoautotrophic metabolism have been recognized ( Figure 5): (1) The formation of H 2 S0 4 by oxidizing molecular sulfur (S°) is characteristic of most Sulfolobales (Shiwers and Brock, 1973;Stetter, 1989b;Segerer and Stetter, 1991b). Usually, oxygen serves as terminal acceptor of electrons.…”

“…This paper will give an overview about the hyperthermophiles. The reader is also referred to other general reviews on hyperthermophiles (Setter, 1989a; Stetter et a/., 1990; Segerer et al, 1991a) and reviews focussing on specified hyperthermophilic taxa (R. Huber and Stetter, 1991a; R. Huber and Stetter, 1991b;Segerer and Stetter, 1991b) which have been published recently.…”

Characterization and identification of thermoacidophilic archaebacteria isolated in Japan.

“…In sulfur-dependent thermophilic archaebacteria, the following five genera have been assigned to the order Sulfolobales: (i) the genus Sulfolobus, which is the type genus and includes the species S. acidocaldarius (3), S. solfataricus (24), S. shibatae (6) and S. metallicus (9), (ii) the genus Acidianus, which includes the species A. brierleyi (2,17) and A. infernus (17), (iii) the genus Metallosphaera, with one species, MM sedula (8), (iv) the genus Stygiolobus, with one species, S. azoricus (18), (v) the genus Desulfurolobus, with one species, D. ambivalens (25). All species of the order Sulfolobales are acidophilic cocci.…”