Bacteria from the Sonoran Desert with nematicidal potential against phytopathogenic nematodes

Abstract

Abstract The use of microorganisms and/or their metabolites (e.g., Bacillus, Pseudomonas, etc.) has been proposed as an eco-friendly alternative for controlling phytopathogenic nematodes (PPNs). However, one of the challenges is that microorganisms can thrive in crops affected by climate change, salt stress and drought. Consequently, the search for microorganisms adapted to these conditions has attracted attention. Deserts are characterized by high temperatures, water scarcity, and high salinity, among other harsh conditions; hence, they are a perfect niche for isolating microorganisms adapted to extreme environments. The purpose of this work was to isolate and characterize bacteria from rhizospheric soil samples collected in the Sonoran Desert with the potential for PPN control. Approximately 100 thermotolerant bacteria were isolated, and among them the secretome of the strain identified as Bacillus paralicheniformis TB197 showed the highest nematicidal activity (96%) against Meloidogyne incognita in vitro. Additionally, in field assays, the TB197 secretome effectively suppressed infections caused by M. enterolobii. In greenhouse experiments, TB197 endospores reduced the severity of infection by 81% compared with the control (p≤0.05). Finally, the efficacy of TB197 endospores at the open field level was demonstrated against M. incognita in the tomato crop, where the galling index (GI) was reduced by 84%, and against Radopholus similisin the banana crop, where root necrosis was reduced by 81%, both compared with the controls (p≤0.05). Owing to their efficacy in controlling PNN infections, the endospores and secondary metabolites secreted by the B. paralicheniformis TB197 strain can be used to develop effective bionematicides.