Reclassification of Olsenella gallinarum as Thermophilibacter gallinarum comb. nov. and description of Thermophilibacter immobilis sp. nov., isolated from the mud in a fermentation cellar used for the production of Chinese Luzhou-flavour Baijiu

Abstract

A novel Gram-stain-positive, strictly anaerobic, elliptical, non-motile and non-flagellated bacterium, designed LZLJ-2^T, was isolated from the mud in a fermentation cellar used for the production of Chinese Luzhou-flavour Baijiu. Growth occurred at 28-45 °C (optimum, 37 °C), at pH 6.0-7.0 (optimum, pH 6.0) and with concentrations of NaCl up to 2 % (w/v; optimum, 0 %). On the basis of 16S rRNA gene sequence similarity, strain LZLJ-2^T belonged to the genus <i>Thermophilibacter</i> and was most closely related to <i>Thermophilibacter mediterraneus</i> Marseille-P3256^T (similarity 96.9 %), <i>Olsenella gallinarum</i> ClaCZ62^T (similarity 96.6 %) and <i>Thermophilibacter provencensis</i> Marseille-P2912^T (similarity 96.4 %). In addition, strain LZLJ-2^T had high similarity to the genus <i>Olsenella</i>, including <i>Olsenella profusa</i> DSM 13989^T (similarity 94.9 %), <i>Olsenella umbonata</i> DSM 22620^T (similarity 94.9 %), <i>Olsenella uli</i> ATCC 49627^T (similarity 94.22 %), <i>Tractidigestivibacter scatoligenes</i> DSM 28304^T (similarity 93.9 %) and <i>Paratractidigestivibacter faecalis</i> KCTC 15699^T (similarity 93.25 %). Comparative genome analysis showed that orthoANI values between strain LZLJ-2^T and <i>Thermophilibacter mediterraneus</i> Marseille-P3256^T, <i>Olsenella gallinarum</i> ClaCZ62^T, <i>Thermophilibacter provencensis</i> Marseille-P2912^T, <i>Olsenella profusa</i> DSM 13989^T, <i>Olsenella umbonata</i> DSM 22620^T, <i>Olsenella uli</i> ATCC 49627^T, <i>Tractidigestivibacter scatoligenes</i> DSM 28304^T and <i>Paratractidigestivibacter faecalis</i> KCTC 15699^T were 78.68, 78.99, 78.29, 73.40, 74.00, 74.30, 75.08 and 77.23 %, and the genome-to-genome distance values were respectively 22.3, 22.5, 22.4, 19.6, 20.5, 19.7, 20.5 and 21.5 %. The genomic DNA G+C content of strain LZLJ-2^T was 65.21 mol%. The predominant cellular fatty acids (>10 %) of strain LZLJ-2^T were C_{18 : 1} <i>cis</i> 9 (33.7 %), C_{14 : 0} (22.0 %) and C_{18 : 1} <i>cis</i> 9 DMA (13.5 %). d-Glucose, sucrose, mannose, maltose, lactose (weak), salicin, glycerol (weak), cellobiose and trehalose (weak) could be used by strain LZLJ-2^T as sole carbon sources. Enzyme activity results showed positive reactions with valine arylamidase, leucine arylamidase, crystine arylamidase, acid phosphatase, alkaline phosphatase, esterase (C4) (weakly positive), naphthol-AS-BI-phosphohydrolase, <i>α</i>-glucosidase and <i>β</i>-glucosidase. The major end products of glucose fermentation were lactic acid and acetic acid. It produced skatole from indole acetic acid, and produced <i>p</i>-cresol from modified peptone-yeast extract medium with glucose. Based on the 16S rRNA gene trees as well as the genome core gene tree, it is suggested that <i>Olsenella gallinarum</i> are transferred to genus <i>Thermophilibacter</i> as <i>Thermophilibacter gallinarum</i> comb. nov. Based on phenotypic, genotypic and phylogenetic data, strain LZLJ-2^T is considered to represent a novel species of the genus <i>Thermophilibacter</i>, for which the name <i>Thermophilibacter immobilis</i> sp. nov. is proposed. The type strain is LZLJ-2^T (=KCTC 25162^T=JCM 34224^T).