Genomic and Metabolic Features of an Unexpectedly Predominant, Thermophilic, Assistant Starter Microorganism, Thermus thermophilus , in Chinese Inner Mongolian Cheese

• Published in: Foods Vol. 10; no. 12; p. 2962
• Main Authors: Zhu, Lin, Hou, Zhaozhi, Hu, Xinyu, Liu, Xu, Dai, Tian, Wang, Xinyu, Zeng, Chunlin, Wang, Yuan, Wang, Caizheng, Yang, Shujing, Cui, Henglin, Wei, Wei
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 02-12-2021; MDPI
• Subjects: Acetic acid; Acidification; Acids; Annotations; Bacteria; Carbon sources; Cheese; Citric acid; Community structure; Dairy products; Enzymes; Fermentation; Flavor; Flavors; Food science; Gene sequencing; Genes; Genetic testing; Genomes; Grasslands; high-throughput sequencing; Impact analysis; Inner Mongolian cheese; Lactic acid; Lactic acid bacteria; Lactose; lactose metabolism; Metabolism; Microorganisms; Milk; Next-generation sequencing; organic acid generation; Organic acids; Pathogens; Propionic acid; Relative abundance; rRNA 16S; Thermophilic microorganisms; Thermus thermophilus; Tricarboxylic acid cycle; Whey; Yeast; Beijing China; China; Inner Mongolia China; Thermus thermophilus; Inner Mongolian cheese; organic acid generation; lactose metabolism; high-throughput sequencing
• ISSN: 2304-8158; 2304-8158
• DOI: 10.3390/foods10122962

Inner Mongolian cheese is a traditional dairy product in China. It is produced without rennet, using naturally acidified milk that is simmered to achieve whey separation. In order to analyse the impact of simmering on the microbial community structure, high-throughput sequencing was performed to obtain bacterial 16S rRNA sequences from cheeses from the Ordos (ES), Ulanqab (WS), Horqin (KS) and Xilingol (XS) grasslands of Inner Mongolia. The relative abundance of an unexpected microorganism,
, ranged from 2% to 9%, which meant that its dominance was second only to that of lactic acid bacteria (LABs). Genome sequencing and fermentation validation were performed in
N-1 isolated from the Ordos, and it was determined that
N-1 could ingest and metabolise lactose in milk to produce lactate during the simmering process.
N-1 could also produce acetate, propionate, citrate and other organic acids through a unique acetate production pathway and a complete propionate production pathway and TCA cycle, which may affect texture and flavour development in Inner Mongolian cheese. Simultaneously, the large amount of citrate produced by
N-1 provides a necessary carbon source for continuous fermentation by LABs after the simmering step. Therefore,
N-1 contributes to cheese fermentation as a predominant, thermophilic, assistant starter microorganism unique to Chinese Inner Mongolian cheese.