Preliminary Assessment of Cultivable Bacterial Diversity During Coffee Post-Harvest Fermentation in Southern Ecuador via 16S rRNA Gene Barcoding

The organoleptic profile of coffee is modulated by microbially mediated fermentation processes; thus, characterizing the coffee microbiome is essential for the specialty coffee industry. This research investigated three coffee farms in Loja, Ecuador, to determine the cultivable bacterial diversity in coffee cherries (Coffea arabica var. Geisha) subjected to different post-harvest processing methods. Bacteria were isolated on Trypticase Soy Agar (TSA), Blood Agar Base, and MacConkey Agar after a broth enrichment step. Isolates were initially grouped into 14 morphotypes (MT) based on colony morphology and Gram staining. Molecular identification was performed by 16S rRNA gene sequencing, followed by phylogenetic analysis and Operational Taxonomic Unit (OTU) delimitation at a 99% identity threshold. Although 45 purified strains (19 Gram-positive and 26 Gram-negative) were initially clustered, morphological characterization showed significant taxonomic limitations compared with molecular tools. Molecular analysis identified nine genera and 19 bacterial genotypes, with Lactococcus lactis and Enterobacter spp. being the most frequently recovered and resilient taxa across all treatments. Statistical analyses (PERMANOVA and PCA) revealed no significant differences in bacterial community composition among post-harvest processes (Natural or Carbonic Maceration) or among farms, indicating that the predominant cultivable isolates remained consistent under the conditions evaluated, as presented here. According to the literature, several of the recovered species have functional roles in coffee fermentation, providing a baseline for the future development of starter cultures to optimize and standardize coffee sensory quality in southern Ecuador.