The 16S rRNA gene sequences of T. marianensis
share 98.3 to 98.6% sequence identity with the other type strains of the genus Thermaerobacter
] and T. nagasakiensis
being the closest relative. Outside the genus members of the recently proposed genus “Calditerricola”
] and the genus Moorella
] share the highest degree of sequence similarity. The genomic survey sequence database (gss) contains as best hits several 16S rRNA gene sequence from The Sorcerer II Global Ocean Sampling Expedition: Northwest Atlantic through Eastern Tropical Pacific [11
] at a similarity level of only 84%. No phylotypes from environmental samples database (env_nt) could be linked to the species T. marianensis
or even the genus Thermaerobacter
, indicating a rather rare occurrence of members of this genus in the habitats screened thus far (as of November 2010).
A representative genomic 16S rRNA sequence of T. marianensis
was compared using NCBI BLAST under default values (e.g., considering only the best 250 hits) with the most recent release of the Greengenes database [12
] and the relative frequencies of taxa and keywords, weighted by BLAST scores, were determined. The five most frequent genera were Thermaerobacter
(3.6%) and Bacillus
(3.4%). Regarding hits to sequences from other members of the genus, the average identity within HSPs (high-scoring segment pairs) was 98.1%, whereas the average coverage by HSPs was 96.3%. The species yielding the highest score was Thermaerobacter subterraneus
. The five most frequent keywords within the labels of environmental samples which yielded hits were 'compost(ing)' (6.1%), 'municipal' (2.9%), 'scale' (2.7%) and 'process/stages' (2.6%). Environmental samples which yielded hits of a higher score than the highest scoring species were not found.
shows the phylogenetic neighborhood of T. marianensis 7p75aT in a 16S rRNA based tree. The sequences of the two 16S rRNA gene copies differ from each other by two nucleotides, and differ by up to two nucleotides from the previously published 16S rRNA sequence (AB011495), which contains one ambiguous base call.
Figure 1 Phylogenetic tree highlighting the position of T. marianensis 7p75aT relative to the other type strains within the family. The tree was inferred from 1,489 aligned characters [13,14] of the 16S rRNA gene sequence under the maximum likelihood criterion (more ...)
The cells of T. marianensis
are generally rod-shaped (0.3-0.6 × 2-7 µm), straight to slightly curved with rounded ends (). The cells can be arranged in pairs [2
]. T. marianensis
is a Gram-positive, spore-forming bacterium (). At stationary phase cells, may stain Gram-negative. Motility and flagella have not been observed [2
], but genes for biosynthesis and assembly of flagella have been identified in the here reported genome sequence. The organism is a strictly aerobic chemoheterotroph. T. marianensis
is a typical marine bacterium and requires sea salts (0.5-5%, optimum 2%) in media for good growth [2
]. The temperature range for growth is between 50°C and 80°C, with an optimum at 75°C [2
]. The pH range for growth is 5.4-9.5, with an optimum at pH 7.0-7.5 [2
]. T. marianensis
is able to grow on yeast extract, peptone and casein. It utilizes carbohydrates like starch, xylan, chitin, maltose, maltotriose, cellobiose, lactose, trehalose, sucrose, glucose, galactose, xylose, mannitol, inositol. The strain is also able to grow on amino acids like casamino acids, valine, isoleucine, cysteine, proline, serine, threonine, asparagine, glutamine, aspartate, glutamate, lysine, arginine and histidine. T. marianensis
is able to grow well on various carboxylic acids like propionate, 2-aminobutyric acid, malate, pyruvate, tartarate, succinate, lactate, acetate and glycerol [2
Scanning electron micrograph of T. marianensis 7p75aT
Table 1 Classification and general features of T. marianens 7p75aT according to the MIGS recommendations .
The cellular polyamines of the strain 7p75aT
were identified as N4-bis(aminopropyl)spermidine, agmatine, spermidine, and spermine [30
]. The major cellular fatty acids were composed of 15-methyl-hexadecanic acid (52.3%), myristoleic acid (27.6%) and 14-methyl hexadecanoic acid (9.3%) [2
]. No data are available for polar lipids and peptidoglycan type of the cell wall.