Chai Lijuan

Bio: Chai Lijuan is an academic researcher from Jiangnan University. The author has contributed to research in topics: Fermentation & Lactic acid. The author has an hindex of 6, co-authored 25 publications receiving 91 citations.

Zooming in on Butyrate-Producing Clostridial Consortia in the Fermented Grains of Baijiu via Gene Sequence-Guided Microbial Isolation.

Abstract: Butyrate, one of the key aroma compounds in Luzhou-flavor baijiu, is synthesized through two alternative pathways: butyrate kinase (buk) and butyryl-CoA: acetate CoA-transferase (but). A lack of knowledge of butyrate-producing microorganisms hinders our ability to understand the flavor formation mechanism of baijiu. Here, temporal dynamics of microbial metabolic profiling in fermented grains (FG) was explored via PICRUSt based on 16S rRNA gene sequences. We found Bacilli and Bacteroidia were the major potential butyrate producers in buk pathway at the beginning of fermentation, while later Clostridia dominated the two pathways. Clone library analysis also revealed that Clostridia (~73% OTUs) was predominant in buk pathway throughout fermentation, followed by Bacilli and Bacteroidia, and but pathway was merely possessed by Clostridia. Afterward, Clostridia-specific 16S rRNA gene sequencing demonstrated Clostridium might be the major butyrate-producing genus in two pathways, which was subsequently evaluated using culture approach. Seventeen Clostridium species were isolated from FG based on 16S rRNA gene sequence-guided medium prediction method. Profiles of short-chain fatty acids and but and buk genes in these species demonstrated phylogenetic and functional diversities of butyrate-producing Clostridium in FG. These findings add to illustrate the diversity of potential butyrate producers during brewing and provide a workflow for targeting functional microbes in complex microbial community.

A taxonomic note on the genus Lactobacillus: Description of 23 novel genera, emended description of the genus Lactobacillus Beijerinck 1901, and union of Lactobacillaceae and Leuconostocaceae.

Abstract: The genus Lactobacillus comprises 261 species (at March 2020) that are extremely diverse at phenotypic, ecological and genotypic levels. This study evaluated the taxonomy of Lactobacillaceae and Leuconostocaceae on the basis of whole genome sequences. Parameters that were evaluated included core genome phylogeny, (conserved) pairwise average amino acid identity, clade-specific signature genes, physiological criteria and the ecology of the organisms. Based on this polyphasic approach, we propose reclassification of the genus Lactobacillus into 25 genera including the emended genus Lactobacillus, which includes host-adapted organisms that have been referred to as the Lactobacillus delbrueckii group, Paralactobacillus and 23 novel genera for which the names Holzapfelia, Amylolactobacillus, Bombilactobacillus, Companilactobacillus, Lapidilactobacillus, Agrilactobacillus, Schleiferilactobacillus, Loigolactobacilus, Lacticaseibacillus, Latilactobacillus, Dellaglioa, Liquorilactobacillus, Ligilactobacillus, Lactiplantibacillus, Furfurilactobacillus, Paucilactobacillus, Limosilactobacillus, Fructilactobacillus, Acetilactobacillus, Apilactobacillus, Levilactobacillus, Secundilactobacillus and Lentilactobacillus are proposed. We also propose to emend the description of the family Lactobacillaceae to include all genera that were previously included in families Lactobacillaceae and Leuconostocaceae. The generic term 'lactobacilli' will remain useful to designate all organisms that were classified as Lactobacillaceae until 2020. This reclassification reflects the phylogenetic position of the micro-organisms, and groups lactobacilli into robust clades with shared ecological and metabolic properties, as exemplified for the emended genus Lactobacillus encompassing species adapted to vertebrates (such as Lactobacillus delbrueckii, Lactobacillus iners, Lactobacillus crispatus, Lactobacillus jensensii, Lactobacillus johnsonii and Lactobacillus acidophilus) or invertebrates (such as Lactobacillus apis and Lactobacillus bombicola).

Can we control microbiota in spontaneous food fermentation? – Chinese liquor as a case example

Abstract: Background Fermented foods, with a history as long as the human civilization, form an indispensable constituent in our daily life. However, most fermented foods are produced by spontaneous fermentation, and the fermentation processes are still uncontrolled. To ensure consistent food quality, it is of paramount importance to understand and control the spontaneous food fermentations. Scope and approach In spontaneous food fermentations, metabolic activity of a succession of complex microbiota results in desired flavour that is the key criterion to decide consumers’ preference. Therefore, flavour compound formation by microbial metabolism can be used as the control target in spontaneous food fermentations. However, relatively little is known about the complexity of the microbiota associated with the flavour compound formation. Therefore, in this review by using Chinese liquor as a model system, we present key biotechnological aspects of the microbiota crucial for flavour of fermented foods, including the driving forces for the microbiota succession, flavour compound formation, and the regulation of flavour compound formation. Key findings and conclusions Core microbiota, associated with flavour compound formation, can be identified and eventually used to construct a synthetic (i.e. designed) microbiota. Meanwhile, key environmental factors, affecting the core microbiota, can also be identified and controlled to regulate the synthetic microbiota. Furthermore, modelling can be used to predict, optimize and control the flavour compound formation by the synthetic microbiota, so that such spontaneous food fermentations can become controllable, with the ultimate goal to monitor, control, and improve the quality, productivity and safety of fermented foods.