High-throughput sequencing-based study on bacterial community structure and functional prediction of fermented bean curd from different regions in China

In order to understand the bacterial community structure, microbial safety, and functional diversity of traditional fermented food-sufu (fermented bean curd) in China, high-throughput sequencing technology was employed to systematically analyze the bacterial community composition and functional profiles of sufu samples from eight different regions in China (Zunyi, Guizhou; Xiushan, Chongqing; Chengdu, Sichuan; Xinhua, Hunan; Ji'an, Jiangxi; Mouding, Yunnan; Guilin, Guangxi; and Shilin, Kunming). The results revealed that the predominant bacterial phyla in sufu included Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteriota, with key genera such as Pseudomonas, uncultured Enterobacteriaceae, and Lactococcus. The sample from Ji'an, Jiangxi (JXR5), exhibited the highest bacterial species richness, while the sample from Shilin, Kunming (KMR8), showed the highest species diversity, indicating significant impacts of geographical location and production processes on microbial communities. Functional analysis demonstrated that the bacterial communities in sufu were primarily involved in metabolic pathways such as chemoheterotrophy, aerobic chemoheterotrophy, and fermentation. The sample from Xiushan, Chongqing (CQR2), had the highest proportion of fermentation-related functions, contributing to the formation of a finer texture and richer flavor. The sample from Guilin, Guangxi (GXR7), exhibited the highest aromatic compound degradation function, which may enhance flavor or reduce undesirable odors. Additionally, significant variations were observed in functions such as nitrate reduction, nitrogen respiration, and nitrate respiration among different samples, suggesting that microbial diversity in nitrogen metabolism may influence the safety and quality of sufu. This study highlights the regional characteristics and functional diversity of bacterial communities in sufu, providing a scientific basis for optimizing production processes and developing region-specific products.