A Proteomic Approach Provides New Insights into the Control of Soil-Borne Plant Pathogens by Bacillus Species

Abstract

Beneficial microorganisms (also known as biopesticides) are considered to be one of the most promising methods for more rational and safe crop management practices. We used Bacillus strains EU07, QST713 and FZB24, and investigated their inhibitory effect on Fusarium. Bacterial cell cultures, cell-free supernatants and volatiles displayed varying degrees of suppressive effect. Proteomic analysis of secreted proteins from EU07 and FZB24 revealed the presence of lytic enzymes, cellulases, proteases, 1,4-β-glucanase and hydrolases, all of which contribute to degradation of the pathogen cell wall. Further proteomic investigations showed that proteins involved in metabolism, protein folding, protein degradation, translation, recognition and signal transduction cascade play an important role in the control of Fusarium oxysporum. Our findings provide new knowledge on the mechanism of action of Bacillus species and insight into biocontrol mechanisms.

<i>Bacillus subtilis Strains</i> with Antifungal Activity against the Phytopathogenic Fungi

“…It is known that extracellular hydrolases make important contributions to the antimicrobial potential of antagonists. It was shown that synthesis of extracellular hydrolases correlates with antifungal potential because some hydrolytic enzymes are involved in the degradation of phytopathogenic micromycetes' cell wall [10] [38]. It was also suggested that pectinases and amylases contribute to the colonization of roots by bacteria and therefore may play an important role in plant growth stimulation [28].…”

“…Bacteria can promote plant growth through a number of mechanisms, such as improvement of plant nutrition; induction of systemic resistance; toxicity to pests and antagonism pathogens [5] [6] [7]. The antagonistic activity of Bacillus is associated with the synthesis of various antimicrobial peptides [8] [9], secreted enzymes [10], proteins [11] and volatile organic compounds (VOCs) [5] [10]. Many Bacillus isolates were shown to have antifungal activity against phytopathogenic fungi that make them good biocontrol candidates [12] [13] [14].…”

Microbial Endophytes that Live within the Seeds of Two Tomato Hybrids Cultivated in Argentina

“…Then, a 5 mm mycelial plug was placed in the center of the plate that was incubated at 25 • C. After 4 days the fungal growth was measured. The inhibition activity was calculated with the formula: Inhibition (%) = [(Growth in control − Growth in treatment)/Growth in control] × 100 [39].…”

Smart biologics for crop protection in agricultural systems

“…Recent investigations into VOCs have shown that the production of 3-hydroxy-2-butanone (acetoin) by Bacillus strains EU07 and FZB24, but not by QST713 (Baysal et al, 2013), can serve as an agent for triggering growth promotion in Arabidopsis thaliana (Munimbazi et al, 1998;Zhao, 2006). Previously, we reported a similar observation in which an EU07 treatment of plants resulted in increased plant height in comparison to that observed with QST713 (Baysal et al, 2008).…”

“…In our recent investigation into the effect of Bacillus species on soilborne plant pathogens, we detected an upregulated protein showing similarity to SAM-dependent methyltransferases (Baysal et al, 2013). It has been known that ACC synthase converts S-adenosylmethionine (AdoMet) into ACC, which is thereafter converted to ethylene by ACC oxidase.…”