The most closely related 16S rRNA gene sequences from cultivated strains that are stored in Genbank originate from isolates classified into neighboring genera within the
Promicromonosporaceae. Among them are some
Isoptericola species isolated from different habitats, including soil, tufa, decayed wood and the hindgut of the humus-feeding larva of the beetle
Pachnoda ephippiata. Sequences of 16S rRNAs from several uncultivated bacteria detected in midgut and hindgut of
P. ephippiata (AJ576375, AJ576390, AJ576391 AJ576404, AJ576378, AJ576417) [
2] are apparently the most closely related phylotypes, with 96-97% sequence similarity. Environmental samples from metagenomic surveys do not surpass 92% sequence similarity, indicating that members of the species are not heavily represented in the so far genomically screened habitats (status July 2009).
shows the phylogenetic neighborhood of X. cellulosilytica XIL07T in a 16S rRNA based tree. The sequences of the three copies of the 16S rRNA gene in the genome differ by up to four nucleotides, and differ by up to five nucleotides from the previously published sequence generated from DSM 15894 (AF403541).
Based on thin section EMs, cells of strain XIL07
T were described as coccoid (approximately 1.1 x 0.8 µm) that occur singly [
1]. However, SEM images () show coccobacillary forms and short rods, as known from other members of the
Promicromonosporaceae:
Cellulosimicrobium,
Isoptericola and
Promicromonospora (). Strain XIL07
T is Gram-positive, aerobic or facultatively anaerobic, nonmotile and non-spore-forming. Colonies grown on YED are white-to-cream colored and their morphology is circular, smooth and mostly flat. Strain XIL07
T utilizes L-arabinose, carboxymethylcellulose, mannose, maltose, rhamnose, starch and xylan as sole carbon source, and produces acid from amygdalin, L-arabinose, arbutin, cellobiose, fructose, galactose, getobiose, glucose, glycerol, glycogen, lactose, lyxose, maltose, mannose, melozitose, rhamnose, salicin, sucrose, trehalose, turanose and D-xylose. No growth was observed with acetate, citrate, gluconate, inositol, malate or mannitol as carbon sources. Strain XIL07
T actively produces amylases, cellulases, gelatinase, xylanases and β-galactosidase and shows weak catalase activity. Esculin was hydrolyzed and nitrate was not reduced [
1].
| Table 1Classification and general features of X. cellulosilytica XIL07T according to the MIGS recommendations [7] |
Chemotaxonomy
The cell wall of
X. cellulosilytica XIL07
T contains A4α-type peptidoglycan (L-Lys-D-Asp). Cell wall sugars are galactose and rhamnose. Mycolic acids are absent. Strain XIL07
T contains menaquinone MK-9(H4) as the major respiratory lipoquinone and a lower amount of MK-8(H4). The cellular fatty acid pattern is composed of iso- and anteiso-branched fatty acids with anteiso-C15:0 (12-methyl tetradecanoic acid) being the predominant and iso-C15:0 the minor fatty acid. The major polar lipids are phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannosides and other unidentified phosphoglycolipids [
1].