Dynamic evolution and correlation between microorganisms and metabolites during manufacturing process and storage of Pu-erh tea

The quality and safety of Pu-erh tea are largely determined by microorganisms, processing and storage conditions. The systemic co-relationship between microbiome and metabolomics during manufacturing of Pu-erh tea is not fully clarified. We comprehensively explored the microbial and metabolic dynamic evolution and revealed the decisive factors for the quality and safety of Pu-erh tea based on creative methods. The results showed that fungal abundance increased in the middle of pile fermentation period and then decreased during storage, but the bacterial abundance increased in the initial stage, subsequently decreased and finally increased. All microorganism species as well as dominant fungi and bacteria were identified during different processing steps. A total of 209 metabolites were identified and 50 of them were characterized as critical metabolites responsible for metabolic changes. Multivariate analysis verified that these critical metabolites were generated by specific dominant species. The environmental condition exhibited a great effect on the growth and reproduction of bacteria, but less than 10% of the dominant fungi exhibited significant correlation with temperature and humidity. In conclusion, our results revealed the microbial composition is the critical factor in changing the metabolic profile and provided a theoretical basis for improving the quality and safety of Pu-erh tea.