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

Aida Esther Peñuela-Martínez,Magally Romero-Tabarez,Arley David Zapata-Zapata

doi:10.25186/.v16i.1825

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 camefrom 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 significantdifferences 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. Key words: Catabolic profiles; Coffee quality; Diversity indices.

Highlights

Fermentation is a necessary stage within the coffee’s wet process that naturally removes mucilage
The changes in microbial population are reflected in the variations in the patterns of use of carbon sources, which can be measured through a technique called community-level physiological profile (CLPP) (Weber; Legge, 2010), using the system BIOLOGTM
The fermentation conditions modified the environment in which the microorganisms interacted, generating different transformations of the substrates, mainly carbohydrates and organic acids

Summary

Introduction

Fermentation is a necessary stage within the coffee’s wet process that naturally removes mucilage This process is spontaneously conducted by microorganisms that are found in the fruit and in the environment and perform a series of transformations that result in the formation of compounds that might influence the quality of the grain. Attributes such as highlighted acidity and aroma are related to the wet process that yields the coffee, in which fermentation has an important role (Joët et al, 2010; Gonzales-Rios et al, 2007; De Bruyn et al, 2017; Worku et al, 2018; Pereira et al, 2019). The CLPP approach allows the identification of functional profiles in the communities as well as their preferences for the consumption of carbohydrates and other substrates under different conditions, allowing a better understanding of the microorganism-quality relationship, the metabolic activity of the communities present and the differences in their behavior between the given fermentation conditions

Results

Discussion

Conclusion