Bioprospection of Native Antagonistic Rhizobacteria From the Peruvian Coastal Ecosystems Associated with Phaseolus vulgaris

Phaseolus vulgaris is originally from the American continent. It is renowned as one of the preferred legume choice in the Peruvian market, due to its high content of nutrients. The Peruvian coast valleys are key-production areas for local varieties of the common bean crops. Soil-borne plant pathogens, however, favored by soil and environmental conditions, may reduce crop production. The aim of this study was to conduct a bio prospection of the antagonistic native bacteria of the north, south and central part of the coastal areas related to the common bean. A collection of 26 strains isolated from the rhizosphere of common bean plants showed high potential to control the growth of Sclerotinia, Fusarium and Rhizoctonia due to the production of both volatile and non-volatile organic compounds. Most of the strains were able to suppress fungal growth due to the presence of non-volatile organic compounds, such as hydrolytic enzymes, siderophores and antifungal lipopeptide production. Bacillus IcBac2.1 strain showed a remarkable ability to halt the majority of phytopathogens producing antifungal lipopeptides. The crude lipopeptides were soluble in polar solvents and remained stable at high temperatures and low pH. Strains were also able to inhibit fungal growth through volatile organic compounds. Alcaligenes TvPs2.4 and Pseudomonas TvPs1.6 showed the highest inhibition strength against the tested phytopathogens. Each strain produced 21 volatile organic compounds detected by SPME/GC–MS analysis. The compounds with the highest concentration were dimethyl disulfide and d-limonene. The 16S rRNA gene sequence confirmed that the strains were closely related to Bacillus, Paenibacillus, Achromobacter, Pseudomonas, Serratia and Alcaligenes.