Microbial ecology of selected traditional Ethiopian fermented products

Abstract

The consumption of traditional fermented foods and beverages plays an important role in the diet of Ethiopia, providing significant nutritional and health benefits to the local population. The present study aimed to investigate the microbial ecology and diversity of nine types of fermented products. These include two foods (Kotcho and Injera), one food condiment (Datta), and six beverages (Tej, Tella, Cheka, Kinito, Borde, and Shamita). A combination of metataxonomic and culturomic approaches was used to achieve a comprehensive characterization of the bacterial communities, together with a thorough physicochemical characterization of the fermented products. This study provides one of the most comprehensive microbial characterizations of a wide selection of Ethiopian fermented products, highlighting that some bacterial species involved in the fermentation processes could contribute to the safety and nutritional quality of fermented foods and, based on previous studies, could also play a key role in enhancing their potential probiotic properties.

Keywords: Ethiopian fermented products; culturomics; metataxonomics; microbial ecology; traditional fermented foods and beverages.

Figure 1

Traditional fermented beverages (A) Borde, (B) Cheka, (C) Kinito, (D) Shamita, (E) Tej, (F) Tella; food condiment (G) Datta; and foods (H) Kotcho and (I) Injera analyzed in this study.

Figure 2

Chemical characterization of the nine fermented products analyzed. (A) Biochemical composition of the analyzed samples, expressed in milligrams of compound per gram of sample. The molecules represented include sugars, ethanol, and organic acids. (B) Composition of organic acids in the analyzed samples, expressed in milligrams of compound per gram of sample. The organic acids analyzed are acetic, citric, lactic, gluconic, and glutamic acids. (C) pH values of the analyzed samples.

Figure 3

Alpha diversity values for traditional fermented beverages and foods of Ethiopia. This figure presents the alpha diversity values for each of the traditional fermented beverages and foods of Ethiopia. The calculated values include species richness (S) which quantifies the total number of different bacterial species (Amplicon Sequence Variant, ASV) present in the fermented products. Shannon Index (H′) reflects the diversity and evenness of species distribution and Simpson Index (D) which expresses the probability that two individuals belong to the same species.

Figure 4

Relative abundance of bacterial phyla identified in the nine fermented products analyzed.

Figure 5

Analysis of nine fermented products from Ethiopia. (A) Principal Coordinates Analysis (PCoA) at the species level for the nine fermented products. (B) Heatmap showing the relative abundance (%) of the 20 most prevalent species across the nine fermented products.

Figure 6

Heatmap of genera isolated from each sample. This heatmap illustrates the number of different genera isolated from each sample. The genus level of strains was determined by partial 16S rRNA gene sequencing of isolates. The color score, ranging from 4 to 0, indicates the number of different species belonging to the same genera isolated in each sample, with 4 representing the highest number of different species and 0 the lowest. The symbol “*” highlights genera isolated by culture techniques but not detected in the metataxonomic analysis of the samples. Only genera with a relative abundance higher than 0.001% were considered detected.