<i>Paenibacillus</i> sp. Strain UY79, Isolated from a Root Nodule of <i>Arachis villosa</i> , Displays a Broad Spectrum of Antifungal Activity

Abstract

A nodule-inhabiting <i>Paenibacillus</i> sp. strain (UY79) isolated from wild peanut (Arachis villosa) was screened for its antagonistic activity against diverse fungi and oomycetes (Botrytis cinerea, Fusarium verticillioides, Fusarium oxysporum, Fusarium graminearum, Fusarium semitectum, Macrophomina phaseolina, Phomopsis longicolla, Pythium ultimum, Phytophthora sojae, Rhizoctonia solani, Sclerotium rolfsii, and Trichoderma atroviride). The results obtained show that <i>Paenibacillus</i> sp. UY79 was able to antagonize these fungi/oomycetes and that agar-diffusible compounds and volatile compounds (different from HCN) participate in the antagonism exerted. Acetoin, 2,3-butanediol, and 2-methyl-1-butanol were identified among the volatile compounds produced by strain UY79 with possible antagonistic activity against fungi/oomycetes. <i>Paenibacillus</i> sp. strain UY79 did not affect symbiotic association or growth promotion of alfalfa plants when coinoculated with rhizobia. By whole-genome sequence analysis, we determined that strain UY79 is a new species of <i>Paenibacillus</i> within the Paenibacillus polymyxa complex. Diverse genes putatively involved in biocontrol activity were identified in the UY79 genome. Furthermore, according to genome mining and antibiosis assays, strain UY79 would have the capability to modulate the growth of bacteria commonly found in soil/plant communities. <b>IMPORTANCE</b> Phytopathogenic fungi and oomycetes are responsible for causing devastating losses in agricultural crops. Therefore, there is enormous interest in the development of effective and complementary strategies that allow the control of the phytopathogens, reducing the input of agrochemicals in croplands. The discovery of new strains with expanded antifungal activities and with a broad spectrum of action is challenging and of great future impact. Diverse strains belonging to the <i>P. polymyxa</i> complex have been reported to be effective biocontrol agents. Results presented here show that the novel discovered strain of <i>Paenibacillus</i> sp. presents diverse traits involved in antagonistic activity against a broad spectrum of pathogens and is a potential and valuable strain to be further assessed for the development of biofungicides.