Fungal community dynamics and correlations with physicochemical factors in sealed Paocai brine

Abstract:

[Background] Fungi play an important role in the flavor and texture of Paocai and influence the shelf life of Paocai and its brine. Brine is the traditional method of Paocai production in China, and it is also the key for maintaining the original flavor of Paocai. [Objective] To analyze the dynamics of the fungal community and its relationship with physicochemical factors of Paocai brine in sealed storage. [Methods] The amplicon sequence variants (ASVs) were employed to monitor the dynamics of the fungal community in Paocai brine stored at 25℃ for 30 d. A flow analyzer was used to reveal the changes in physicochemical factors of the brine. [Results] According to the fungal community dynamics and physicochemical factor changes in the Paocai brine, the fungal community succession within 30 d can be divided into three stages (early:1–5 d; middle:6–16 d; late:18–30 d). A total of 461 fungal genera belonging to 226 families, 98 orders, 39 classes of 10 phyla were annotated in the three stages. In the early stage, the fungal composition was complex and changing, and the interactions were strongly influenced by pH and total nitrogen (TN). The middle stage presented changed dominant genera and increased rare genera, and the interactions were weakened and regulated by TN. In the late stage, the number of rare genera kept decreasing, and the community structure was simple, with weak interactions which were influenced by nitrate nitrogen (NN), phosphate (P), and total phosphorus (TP). [Conclusion] The fungal community in the Paocai brine stored at 25℃ for 30 d varied in the early, middle, and late stages. The Paocai brine stored at 25℃ for 30 d was safe to be used within one week and could guarantee the flavor of Paocai. Moreover, cold chain storage could adequately extend the shelf life. It is worth exploring the rich fungal resources in the Paocai system.