Genome mining to elucidate antimicrobial and plant growth promoting potentials in Lactic acid bacteria

The pangenome of lactic acid bacteria (LAB) was constructed with five bacterial strains isolated from oat silage produced by smallholder farmers from a region in the highlands of the Colombian Andes. The goal of this work was to use genome mining to elucidate some potential mechanisms of action associated with plant growth promotion and biocontrol in LAB. Multiple genes were uncovered, including those associated with antibiosis and antimicrobial compound production, genes that induce plant defense and phytohormone activation. Additionally, genome sequencing suggested mechanisms for LAB to protect against abiotic and biotic stress. Furthermore, genes that may improve phosphorus availability and those that might stimulate root growth were present. We then tested some of these findings in vitro. For instance, the biocontrol activity of these strains was evaluated against the fungal pathogens Fusarium oxsyporum f. sp. cubense (Foc R1 and Foc TR4) and the bacterial pathogen Ralstonia solanacearum (Rs). All tested strains showed the ability to significantly inhibit pathogen growth in vitro. The capability of LAB to grow at high concentrations of fusaric acid was demonstrated, suggesting that LAB might have detoxification mechanisms to compete with other microorganisms. Also, the ability of LAB to solubilize phosphate and produce IAA was demonstrated. These two properties might be involved in plant-growth promotion. Here we show that genomic sequencing can be an efficient tool to identify putative biocontrol or plant-growth promoting related sequences for genome mining.