B. Jochimsen et al.: Stetteria hydrogenophila 109 Extremophiles (1998) 2:109–114 © Springer-Verlag 1998
ORIGINAL PAPER
Reinhard Dirmeier · Martin Keller · Doris Hafenbradl
Franz-Josef Braun · Reinhard Rachel · Siegfried Burggraf
Karl O. Stetter
Thermococcus acidaminovorans sp. nov., a new hyperthermophilic
alkalophilic archaeon growing on amino acids
Received: September 24, 1997 / Accepted: January 1, 1998
Abstract From a shallow marine hydrothermal system at
Vulcano (Italy), a new hyperthermophilic member of the
Archaea was isolated. The cells are coccoid – shaped and
possess up to five flagella. They grow between 56° and
93°C (optimum 85°C) and pH 5.0–9.5 (optimum 9.0). The
organism is strictly anaerobic and grows heterotrophically
on defined amino acids and complex organic substrates
such as casamino acids, yeast extract, peptone, meat extract,
tryptone, and casein. Polysulfide and elemental sulfur are
reduced to H
2
S. In the absence of polysulfide or elemental
sulfur, the isolate grows at a significantly reduced rate.
Growth is not influenced by the presence of H
2
. DNA–
DNA hybridization and 16S rRNA partial sequences
indicated that the new isolate belongs to the genus Thermo-
coccus, and represents a new species, Thermococcus
acidaminovorans. The type strain is isolate AEDII10 (DSM
11906).
Key words Archaea · Hyperthermophiles · Thermococcus
acidaminovorans · Defined amino acids · Polysulfide
reduction · Alkaline pH
Introduction
Within their hot biotopes, the Thermococcales play an im-
portant role as decomposers of organic matter (Stetter
1995). These obligately heterotrophic hyperthermophiles
grow on complex substrates, such as yeast extract, meat
extract, peptone, bacterial and archaeal cell homogenates,
and polymers such as casein, gelatine, starch, and chitin
(Fiala and Stetter 1986; Zillig et al. 1983; Neuner et al. 1990;
Huber et al. 1995; Kobayashi et al. 1994; Kengen and Stams
1994). Peptides are fermented, forming fatty acids, CO
2
,
and H
2
(Schönheit and Schäfer 1995). With the exception
of Thermococcus fumicolans (Godfroy et al. 1996) and
Thermococcus litoralis (Rinker and Kelly 1996), members
of Thermococcales are unable to grow on amino acids. From
a shallow marine hydrothermal system in Vulcano, Italy,
a new Thermococcus isolate was obtained which uses
casamino acids or defined amino acids as the sole carbon-
and energy-source, with optimum growth at pH 9.0.
Materials and methods
Collection of samples and isolation
Samples (AEDII10–AEDII12) were taken anaerobically
(Stetter 1982) at a shallow beach (depth 1.0 m) situated at
the base of the reef close to Porto di Levante at Vulcano
Island, Italy. The original temperature of the sampling site
was 95°C. For enrichment, 1 ml of sample was inoculated
into 10 ml medium at pH 8.5 containing per liter: NaCl,
19.45 g; MgCl
2
·6 H
2
O, 12.6 g; Na
2
SO
4
, 3.24 g; CaCl
2
·2 H
2
O,
2.38 g; KCl, 0.55 g; Na
2
CO
3
·10 H
2
O, 0.26 g; KBr, 0.08 g;
SrCl
2
·6 H
2
O, 57 mg; H
3
BO
3
, 22 mg; sodium metasilicate,
4 mg; NaF, 2.4 mg; KNO
3
, 1.6 mg; Na
2
HPO
4
·2 H
2
O, 10 mg;
casamino acids, 0.2%; polysulfide, 6 mM; glycine, 0.1 M. The
enrichments were incubated at 85°C (gas phase: 200 kPa N
2
).
Pure cultures were obtained by serial dilution of positive
enrichments followed by plating. For plating, the medium
was solidified by 2% agar (Oxoid, Basingstoke, UK). The
plates were incubated at 75°C in a pressure cylinder (Balch
and Wolfe 1976) under an atmosphere of 150 kPa N
2
.
Strains, culture conditions, and substrate utilization
Type strains of Thermococcus stetteri (Miroshnichenko et
al. 1989), Thermococcus litoralis (Neuner et al. 1990),
Thermococcus celer (Zillig et al. 1983), Pyrococcus furiosus
(Fiala and Stetter 1986), Thermococcus alcaliphilus (Keller
Communicated by K. Horikoshi
R. Dirmeier() · M. Keller · D. Hafenbradl · F-J. Braun · R. Rachel
S. Burggraf · K. O. Stetter
Lehrstuhl für Mikrobiologie, Universitätsstraße 31, D-93053
Regensburg, Germany
Tel. +49-941-943-3180; Fax +49-941-943-2403
e-mail: Reinhard.Dirmeier@biologie.uni-regensburg.de