The team of Professor Xu Zhenghong of Jiangnan University published the research results of the design and application of functional flora based on the analysis of the traditional process mechanism of Zhenjiang balsamic vinegar in AEM and Food Res Int

Recently, the team of Professor Xu Zhenghong from the School of Bioengineering of Jiangnan University constructed a multi-strain starter based on the analysis of the scientific mechanism of the traditional process of Zhenjiang balsamic vinegar , and successfully applied it to vinegar brewing .
Related research results "Co
nstructing a defined starter for multispecies vinegar fermentation via evaluing the vitality and dominance of functional microbes in autochthonous starter" was officially published in Applied and Environmental Microbiology” (https://doi.
org/10.
1128/AEM.
02175-21) and “Combined ffects of fermentation starters and environmental factors on the microbial community assembly and flavor formation of Zhenjiang aromatic vinegar” was officially published in Food Research International (https://doi.
org/10.
1016/j.
foodres.
2021.
110900)
.

 

Traditional Chinese solid vinegar uses unsterilized raw materials and is brewed in an open multi-strain mixing system
.
The process generally includes the main steps of saccharification (SS) and alcoholic fermentation (AF) of starchy raw materials, solid-state acetic fermentation (AAF) of wine mash and anaerobic sealing and aging (SF)
.
Under the joint action of a variety of microorganisms, the synthesis of various organic acids including acetic acid and volatile flavor substances using alcohol, starch and other raw materials as the main substrates is completed, and finally a rich and unique traditional Chinese vinegar is formed.

.
In recent years, the artificial construction of synthetic flora and its use in traditional process innovation has received extensive attention.
Synthetic flora can be used to quickly start fermentation and ensure the stability of product flavor
.
However, existing studies have failed to systematically elucidate the succession and driving forces of traditional vinegar-brewing microbial communities, as well as their interactions and functions
.
The lack of the above information objectively hinders the rational design and application of artificially constructed flora
.

 

　　The team of Professor Xu Zhenghong from the School of Bioengineering of Jiangnan University has worked closely with Jiangsu Hengshun Group Co.
, Ltd.
for more than 20 years.
function and rational industrial application
.
In this study, Zhenjiang balsamic vinegar was taken as the research object.
(1) The microbial community succession laws in four fermentation stages of Zhenjiang balsamic vinegar and their correlations with changes in environmental factors and flavor metabolites were analyzed.
The total content of organic acids, amino acids and volatile compounds in fermented grain; (2) Using correlation analysis, it was found that pH was a key environmental factor affecting the microbial community in the alcohol fermentation stage, and the ethanol content and reducing sugar content were significantly correlated with the microbial community in the acetic fermentation stage.
(3) SourceTracker analyzed the source of fermentation microorganisms for Zhenjiang balsamic vinegar, and found that the bacterial community that started acetic acid fermentation was mainly derived from fermented grains (i.
e.
Vinegar grains on the 7th day of fermentation), the fungal community was mainly derived from the unsterilized raw material mixture
.
(4) The active dominant species in Zhenjiang balsamic vinegar fermented grains were comprehensively analyzed by multi-omics technology, and their succession laws in the fermentation process were tracked.
It was found that the above dominant microorganisms showed 4 succession patterns.
Class analysis and collinear network analysis revealed the important roles of these dominant species in the fermentation process; (5) isolated and screened representative strains (Acetobacter pasteurianus, Acetilactobacillus jinshanensis, Lactobacillus acidfasti Lactobacillus acetotolerans and L.
helveticus), and constructed a simplified vinegar-brewing synthetic flora, which can quickly start acetic fermentation, and the main flavor of the product is not significantly different from that of traditional craft vinegar
.

 

　　The above research systematically explained the scientific mechanism of Zhenjiang balsamic vinegar's traditional "set mash inoculation" process, deepened the understanding of the relationship between the traditional production process of balsamic vinegar and the formation of flavor, and constructed a multi-strain starter, which innovated food.
Vinegar brewing process
.
The research shows that the application of artificially synthesized microbiome in traditional brewing can be realized by mining the functional microorganisms of brewing
.
However, the construction of artificial communities is by no means a simple choice of several microorganisms.
It is necessary to fully understand the microorganisms involved in each metabolic module and to clarify the interaction and succession patterns between them, so as to rationally design a simplified and stable functional flora, and finally achieve The purpose of optimizing the production process, stabilizing the production process and improving product quality
.

 

　　Huang Ting, a 16th-level doctoral student of our school, is the first author.
The above research work was supported by the National Natural Science Foundation of China (31771967)
.