Identification of Human Pathogenic Bacteria in Plant Roots by Using MALDI-TOF MS Methodology

Bacterial endophytes are a good source of plant growth promoting bacteria to design biofertilizers, but they can include pathogenic species. Since matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) is a reliable method for bacterial identification and all cultivable bacterial species causing human diseases are included in the Biotyper 3.0 database, we used this methodology to analyze a collection of endophytic bacteria isolated from maize roots in Canary Islands. We identified several human pathogens such as Bacillus cereus, Enterobacter cloacae, Kosakonia cowanii (formerly Entrobacter cowanii), Klebsiella pneumoniae, Pantoea agglomerans, Pseudomonas aeruginosa, Pseudomonas fulva, Pseudomonas mendocina, Pseudomonas mosselii, and Staphylococcus epidermidis. These results showed that MALDI-TOF MS is a useful technique in the process of characterization of endophytic bacteria allowing to discard strains belonging to pathogenic species that cannot be included in biofertilizers.