Potential biocontrol actinobacteria: Rhizospheric isolates from the Argentine Pampas lowlands legumes

Abstract

Control of fungal plant diseases by using naturally occurring non-pathogenic microorganisms represents a promising approach to biocontrol agents. This study reports the isolation, characterization, and fungal antagonistic activity of actinobacteria from forage soils in the Flooding Pampa, Argentina. A total of 32 saprophytic strains of actinobacteria were obtained by different isolation methods from rhizospheric soil of Lotus tenuis growing in the Salado River Basin. Based on physiological traits, eight isolates were selected for their biocontrol-related activities such as production of lytic extracellular enzymes, siderophores, hydrogen cyanide (HCN), and antagonistic activity against Cercospora sojina, Macrophomia phaseolina, Phomopsis sp., Fusarium oxysporum, and Fusarium verticilloides. These actinobacteria strains were characterized morphologically, physiologically, and identified by using molecular techniques. The characterization of biocontrol-related activities in vitro showed positive results for exoprotease, phospholipase, fungal growth inhibition, and siderophore production. However, none of the strains was positive for the production of hydrogen cyanide (HCN). Streptomyces sp. MM140 presented the highest index for biocontrol, and appear to be promising pathogenic fungi biocontrol agents. These results show the potential capacity of actinobacteria isolated from forage soils in the Argentine Pampas lowlands as promising biocontrol agents, and their future agronomic applications.

Molecules to Ecosystems: Actinomycete Natural Products In situ

“…Specifically, host plants showed significantly less root and crown rot, and were healthier overall (El-Tarabily et al, 2009). A number of other studies have shown similar results, in various plant systems, where root-inoculated actinomycetes were able to protect the plant from harmful pathogen invasion (Xue et al, 2013; Nabti et al, 2014; Solans et al, 2016). In a notable example, Streptomyces lividans was shown to produce prodiginines on the roots of Arabidopsis thaliana , which antagonized the particularly damaging fungal pathogen Verticillium dahlia (Meschke et al, 2012).…”

Maximization of Siderophores Production from Biocontrol Agents, Pseudomonas aeruginosa F2 and Pseudomonas fluorescens JY3 Using Batch and Exponential Fed-Batch Fermentation

“…Other mechanisms, in addition to siderophores production by fluorescent pseudomonads, were reported that may help in suppressing and controlling fungal pathogens, such as the production of antifungal compounds and lytic enzymes. Solans et al, 2016 studied the role of siderophores as biocontrol agents [50] whereas Arya et al, 2018 revealed that tomato seedlings inoculated with P. fluorescens strains SPs9 and SPs20, which are able to produce siderophores in the soil infected with F. oxysporum, succeeded in controlling wilt disease with high efficiency [5]. Leeman et al, 1996 reported that siderophore-producing P. fluorescens induced systemic resistance against Fusarium wilt of radish [51].…”

Exploring the response of Actinobacteria to the presence of phosphorus salts sources: Metabolic and co‐metabolic processes

“…MM136; MM140; MM141; MM145 and MM147. The strains were selected from a larger collection for their PGPR traits such biological N fixation in NFb, IAA, and siderophore production, exoprotease and phospholipase activities, antifungal effect and P solubilizing in NBRIP agar with Ca 3 PO 4 (unpublished data). These isolates were deposited in GenBank under the following accession numbers: KX530965, KX530966, KX530967, KX530968, and KX530970 for Streptomyces spp.…”

“…These isolates were deposited in GenBank under the following accession numbers: KX530965, KX530966, KX530967, KX530968, and KX530970 for Streptomyces spp. MM136, MM140, MM141, MM145, and MM147, respectively .…”