Solibacillus daqui sp. nov., isolated from high-temperature Daqu.

A Gram-stain-positive, rod-shaped, endospore-forming, aerobic bacterial strain, designated ZS111008T, was isolated from high-temperature Daqu, a starter for production of Chinese Jiang-flavour Baijiu, and was characterized by polyphasic taxonomy. This novel isolate grew in the presence of 0-5 % (w/v) NaCl, at pH 6.0-9.0 and 25-45 °C; optimum growth was observed with 1 % (w/v) NaCl, at pH 8.0 and 30 °C. A comparative analysis of the 16S rRNA gene sequence (1461 bp) of strain ZS111008T showed highest similarity to Solibacillus silvestris DSM12223T (96.7%), followed by Solibacillus cecembensis PN5T (96.6%) and Solibacillus isronensis AMCK01000046 (96.5%). The DNA G+C content of strain ZS111008T was 37.21 mol%. The respiratory quinone was identified as menaquinone-7 and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylserine and one unknown phospholipid. Lys was detected as the diagnostic diamino acid in the cell wall. Based on morphological characteristics, chemotaxonomic characteristics and physiological properties, strain ZS111008T represents a novel species of the genus Solibacillus, for which the name Solibacillus daqui sp. nov. is proposed. The type strain for this proposed species is ZS111008T (=CGMCC 1.19455T=JCM 35214T).

Machine learning based age-authentication assisted by chemo-kinetics: Case study of strong-flavor Chinese Baijiu.

The aged Chinese liquor, Baijiu, is highly valued for its superior organoleptic qualities. However, since age-authentication method and aging-mechanism elucidation of Baijiu is still in the exploratory stage, high-quality aged Baijiu is often replaced by lower-quality, less-aged product with fraudulent mislabeling. Authentic high-quality strong-flavor Baijiu was analyzed by gas chromatography-mass spectrometry. Total esters decreased with aging, while acids, alcohols, aldehydes, ketones, terpenes, pyrazines increased. Although concentrations of partial compounds showed non-monotonic profiling during aging, a close positive linear correlation (R2 = 0.7012) of Baijiu Evenness index (0.55-0.59) with aging time was observed, indicating a more balanced composition in aged Baijiu. The reaction quotient (Qc) of each esterification, calculated by the corresponding reactant and product concentration, approached to the corresponding thermodynamic equilibrium constant Kc. This result demonstrated that the spontaneous transformation driven by thermodynamics explained part of the aging compositional profiling. Furthermore, an aging-related feature selection and an age-authentication method were established based on three models combined with five ranking algorithms. Forty-one key features, including thirty-six compound concentrations, four esterification Qc values and the Evenness index were selected out. The age-authentication based on neural network using forty-one input features accurately predicted the age group of Baijiu samples (F1 = 100 %). These findings have deepened understanding of the Baijiu aging mechanism and provided a novel, effective approach for age-authentication of Baijiu and other liquors.

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.

A novel Gram-stain-positive, strictly anaerobic, elliptical, non-motile and non-flagellated bacterium, designed LZLJ-2T, 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-2T belonged to the genus Thermophilibacter and was most closely related to Thermophilibacter mediterraneus Marseille-P3256T (similarity 96.9 %), Olsenella gallinarum ClaCZ62T (similarity 96.6 %) and Thermophilibacter provencensis Marseille-P2912T (similarity 96.4 %). In addition, strain LZLJ-2T had high similarity to the genus Olsenella, including Olsenella profusa DSM 13989T (similarity 94.9 %), Olsenella umbonata DSM 22620T (similarity 94.9 %), Olsenella uli ATCC 49627T (similarity 94.22 %), Tractidigestivibacter scatoligenes DSM 28304T (similarity 93.9 %) and Paratractidigestivibacter faecalis KCTC 15699T (similarity 93.25 %). Comparative genome analysis showed that orthoANI values between strain LZLJ-2T and Thermophilibacter mediterraneus Marseille-P3256T, Olsenella gallinarum ClaCZ62T, Thermophilibacter provencensis Marseille-P2912T, Olsenella profusa DSM 13989T, Olsenella umbonata DSM 22620T, Olsenella uli ATCC 49627T, Tractidigestivibacter scatoligenes DSM 28304T and Paratractidigestivibacter faecalis KCTC 15699T 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-2T was 65.21 mol%. The predominant cellular fatty acids (>10 %) of strain LZLJ-2T were C18 : 1 cis 9 (33.7 %), C14 : 0 (22.0 %) and C18 : 1 cis 9 DMA (13.5 %). d-Glucose, sucrose, mannose, maltose, lactose (weak), salicin, glycerol (weak), cellobiose and trehalose (weak) could be used by strain LZLJ-2T 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, α-glucosidase and ß-glucosidase. The major end products of glucose fermentation were lactic acid and acetic acid. It produced skatole from indole acetic acid, and produced p-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 Olsenella gallinarum are transferred to genus Thermophilibacter as Thermophilibacter gallinarum comb. nov. Based on phenotypic, genotypic and phylogenetic data, strain LZLJ-2T is considered to represent a novel species of the genus Thermophilibacter, for which the name Thermophilibacter immobilis sp. nov. is proposed. The type strain is LZLJ-2T (=KCTC 25162T=JCM 34224T).