Estudio preliminar del microbioma del bulbo de cebolla como fuente de microorganismos antagonistas para el control de la pudrición postcosecha

Onions are one of the most economically important vegetables in the world, but approximately 30% are lost annually due to post-harvest diseases. In tropical lands, such as those in Central American countries, solar bulb dryers create an ideal environment for the development of rots, which are treated with the application of highly residual agrochemicals. The use of biological control agents at this stage can be a sustainable management option. A preliminary metagenomic analysis of the communities on the bulb surface can help to understand the structure and functionality of an ecosystem and serve as a basis for the development of bio-inputs. This research aimed to analyze the onion bulb surface microbiome using a preliminary and descriptive metagenomic approach and to isolate microorganisms antagonistic to pathogens that cause bulb rot. Microbiome analysis revealed differences between the communities on the surface of onions when dried in a solar dryer (SS) and in the field under direct sunlight (SC). In the taxonomic profile of the solar dryer, the predominance of thermotolerant and pathogenic microorganisms may favor colonization by bacteria causing soft rot, while direct sunlight, combined with a more balanced community of saprophytes, pathogens, and biological control agents, reduces the presence of these bacteria. Of the 108 isolated strains, 3 bacteria were selected for their antagonism against Pseudomonas spp. and one against Penicillium spp., with values of 60.67%, 49.2%, 44.05%, and 24.72%, respectively. The selected bacteria were classified in the genus Pseudomonas and demonstrated potential for use as biological control agents in the post-harvest phase. According to our analysis, the study of the bulb microbiome is the first to be employed in the comparison between onion drying methods in tropical productions.