Functional diversity of microbial communities associated with fermentation processes in coffee (Coffea arabica L.)

Abstract

Mucilage fermentation conducted to degrade and remove coffee mucilage, is an important stage to also define coffee quality, but each microorganism’s contribution to the final quality is not yet known. Therefore, tools are needed to easily identify this relationship in order to be used to enhance coffee quality. The present manuscript describes the behavior of the microbial communities present in fermentations conducted under various conditions, which produced differences in the sensory quality of the coffee as assessed by the community-level catabolic profile approach. The coffee samples came from six different fermentation processes that produced coffee in two quality classifications according to the Specialty Coffee Association (SCA) protocol: very good and excellent. Functional diversity of the microbial communities and substrate consumption were compared through analysis of variance. The multidimensional scaling analysis was used to identify the similarities or differences between treatments. The indices of functional diversity revealed significant differences and direct proportionality with the quality rating. Diversity index (H) was between 2.09 and 2.71 and Evenness was between 1.75 and 2.21. The consumption of groups of substrates was different between fermentations, especially in carbohydrates and carboxylic acids, and the greatest consumption of these was found in the excellent-quality coffee. The different fermentative processes evaluated by this technique showed a high metabolic activity related to the great diversity of substrates given to the microbial communities and microorganisms involved, causing reactions that had influence on the final quality of the product.