Diversity and functional role of bacterial microbiota in spontaneous coffee fermentation in northern Peru using shotgun metagenomics

Peru is the ninth-largest coffee producer and the largest organic coffee exporter worldwide. Specific modifications in the microbial consortia during fermentation control the flavor of coffee. It is still unclear how fermentation duration affects microbial communities. This study aimed to provide insights into the diversity and functional behavior of the bacterial microbiome during coffee fermentation in northern Peru using shotgun metagenomics. Accordingly, metagenomic DNA was extracted and sequenced from samples of the liquid fraction during the short fermentation process (SFP) in Amazonas (6 and 12 h) and long fermentation process (LFP) in Cajamarca (6, 12, 18, 24, and 36 h). Our findings indicate that common (e.g., Acetobacter, Lactobacillus, Leuconostoc, and Weissella) and unique (e.g., Acidiphilium and Methylobacterium) acid-tolerant bacteria from the SFP and LFP play crucial roles and have a positive impact on the sensory qualities of coffee. Specifically, the LFP from San Ignacio might be associated with the high sensory quality of coffee based on the release of catalytic, hydrolase, oxidoreductase, transferase, and transporter enzymes in the InterPro and KEGG profiles. Additionally, these bacterial microorganisms metabolize several compounds (e.g., isoleucine, betaine, galactose, tryptophan, arginine, and cobalamin) into volatile compounds, mainly in the LFP, enhancing the flavor and aroma of coffees. This characteristic suggests that the LFP has a stronger effect on coffee quality than does the SFP on the basis of bacterial diversity and functional prediction. These findings provide new perspectives on the potential biotechnological uses of autochthonous microorganisms to produce superior-quality coffee beans from northern Peru.