Diversity of endophytic bacteria in the fruits of Coffea canephora

Abstract

Endophytic bacteria colonize the internal tissues of plants without causing infection or negative effects on their hosts. This study investigates the occurrence and diversity of culturable endophytic bacteria in the fruits of Coffea canephora at three developmental stages. Isolation and quantification were performed in R2A culture medium, and the diversity was established using molecular methods and analysis of fatty acid methyl esters (FAME). α- and γ-Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes were identified in the investigated community. Kocuria turfanensis and Pantoea vaganswere identified as endophytes for the first time. Of the 18 species that were found, the following seven had not been previously described as endophytic in coffee fruits: Bacillus thuringiensis, Bacillus licheniformis, Agrobacterium tumefaciens, Escherichia coli,Enterobacter hormaechei, Chryseobacterium sp., and Ochrobactrum sp. The diversity of endophytic bacteria varied during the three developmental stages that were investigated, and the diversity was greatest in fruits during the green stage, during which Bacillus subtilis predominated. The number of Gram-positive bacteria was larger than the number of Gram-negative bacteria during the two earliest developmental stages, whereas their numbers were similar during the ripe stage. The diversity was lowest during the ripe stage, and Klebsiella oxytoca was the predominant species at this stage, probably due to the higher caffeine and sugar contents in the fruits. Key words: Coffee, bacterial community, sequencing, 16S rDNA, FAME