DIVERSITY OF NITROGEN-FIXING BACTERIA IN COFFEE CROPS (Coffea arabica L.)

Abstract: Microorganisms play a crucial role in plant growth and development. Nitrogen-Fixing Bacteria (NFB), for instance, are essential to nitrogen nutrition. However, few studies have focused on this important community of coffee agrosystems. Therefore, this study aims to evaluate the diversity of NFB in soil and fruits from eight coffee farms. After DNA extraction, the V4 hypervariable region of 16S rDNA was amplified and sequenced in Illumina MiSeq sequencer. The prediction of potential nitrogen-fixing bacteria was performed by PICRUSt2. One hundred and eighteen ASVs were predicted as potential nitrogen-fixing. While 115 ASVs were detected in fruits, only four were found in fruits. The most abundant phylum was Proteobacteria (71 %), followed by Firmicutes (23 %). The relative abundance of the NFB concerning the whole bacterial community ranged from three to almost six percent. Only one ASV of the Rhizobiaceae family was found, simultaneously, in fruits and soil. The Bradyrhizobium genus was found in all soil samples. We conclude that important NFB are part of the microbiota present in the soil and coffee fruit and that there is a sharing between them. There is evidences that Bradyrhizobium genus can be considered a significant component of the core microbiota in coffee soil.