Exploring microbial diversity and quality in fermented foods from tropical and non-tropical regions

The unique tropical climate, characterized by elevated temperatures and humidity, significantly influences the specific characteristics of microbial communities. In this study, we analyzed metagenomic data from 345 fermented food samples collected across 14 tropical and non-tropical countries. The Shannon and InvSimpson indices, along with Principal Coordinate Analysis (PCoA), indicated a significantly higher microbial diversity in tropical regions ( p ≤ 0.001). Linear Discriminant Analysis Effect Size (LEfSe) analysis identified Limosilactobacillus fermentum (LDA = 4.85) and Lactiplantibacillus plantarum (LDA = 4.66) as significantly enriched in tropical samples. Lactiplantibacillus plantarum isolated from tropical regions demonstrated superior characteristics, including significantly enhanced growth ( p < 0.01), lower pH (3.42, p ≤ 0.001), elevated viable counts (8.81 × 10^8 CFU/mL, p ≤ 0.001), and increased levels of proline, cystathionine, GABA, threonine, phenylalanine, isoleucine, and leucine ( p < 0.05). Correlation analysis linked viable counts, total essential free amino acids, proline, cystathionine, threonine, phenylalanine, and isoleucine to 19 COG functional categories (including C [energy production and conversion], E [amino acid metabolism and transport], and others) ( p ≤ 0.01), while pH negatively correlated with these categories. GABA and leucine were correlated with category G (carbohydrate transport and metabolism), and total amino acids correlated with categories F (transport and metabolism of nucleotides), N (cell motility), and O (molecular chaperones) ( p ≤ 0.01). These findings underscore the enhanced metabolic activity and nutritional potential of Lactiplantibacillus plantarum isolated from tropical regions, supporting its application in fermented foods and the development of regional products.