Antimicrobial activity of Epsilon-Poly-l-lysine against phytopathogenic bacteria

Abstract

Antimicrobial peptides (AMps) are components of immune defense in many organisms, including plants. they combat pathogens due to their antiviral, antifungal and antibacterial properties, and are considered potential therapeutic agents. An example of AMp is epsilon-poly-l-lysine (epL), a polypeptide formed by ~ 25 lysine residues with known antimicrobial activity against several human microbial pathogens. EPL presents some advantages such as good water solubility, thermal stability, biodegradability, and low toxicity, being a candidate for the control of phytopathogens. Our aim was to evaluate the antimicrobial activity of EPL against four phytobacterial species spanning different classes within the Gram-negative phylum Proteobacteria: Agrobacterium tumefaciens (syn. Rhizobium radiobacter), Ralstonia solanacearum, Xanthomonas citri subsp. citri (X. citri), and Xanthomonas euvesicatoria. The minimum inhibitory concentration (MIC) of the peptide ranged from 80 μg/ml for X. citri to 600 μg/ml for R. solanacearum and X. euvesicatoria. Two hours of MIC exposure led to pathogen death due to cell lysis and was enough for pathogen clearance. The protective and curative effects of EPL were demonstrated on tomato plants inoculated with X. euvesicatoria. Plants showed less disease severity when sprayed with EPL solution, making it a promising natural product for the control of plant diseases caused by diverse proteobacteria. Phytobacteria constitute an important group of plant pathogens that reduce yields of valuable crops. They are easily disseminated and can spread quickly, causing severe bacterial infections that are difficult to control 1. Globally, the estimate is that 20-30% of crops are lost annually due to plant diseases 2. Proteobacteria is a diverse group comprising many important phytopathogenic bacteria that negatively impact agricultural production worldwide 3. In terms of scientific and economic importance, Ralstonia solanacearum, Agrobacterium tumefaciens and Xanthomonas axonopodis pathovars are considered the second, third and sixth most relevant phytobacteria, respectively 4,5. R. solanacearum is the causative agent of bacterial wilt, the main vascular disease of bacterial etiology in the world, and one of the most destructive diseases for over 200 plant species. Yield losses can reach 90% in tomato and potato crops, and 30% in tobacco 5,6. A. tumefaciens (updated scientific name Rhizobium radiobacter) is responsible for causing crown gall, one of the most important plant diseases of grape, cherry, walnut, woody and herbaceous perennials, as well as roses and other ornamentals 7-9. Xanthomonas citri subsp. citri is also an important pathogen that causes citrus canker, one of the most severe diseases of all commercially important citrus varieties leading to enormous yield loss, increasing production costs due to control and prevention 10-12. Xanthomonas euvesicatoria is the causal agent of bacterial spot and can reduce the yield of tomato and pepper up to 50%, through reduced photosynthetic capacity and defol...

Xylella fastidiosa subsp. pauca Strains Fb7 and 9a5c from Citrus Display Differential Behavior, Secretome, and Plant Virulence

“…Cultures were maintained for up to 10 days at 28 • C in a rotary shaker at 200 rotations per minute. Samples to be analyzed by scanning electron microscopy (SEM) were prepared according to Rodrigues et al [91] and analyzed at CEMI, Unifesp, Brazil.…”

Recent Advances in Epsilon-Poly-L-Lysine and L-Lysine-Based Dendrimer Synthesis, Modification, and Biomedical Applications

“…Remarkable abilities, such as edible, biocompatible, and broad (Ge et al, 2019); (B) The structure of EPL, one of the linear PLL forms; (C) Different molecular structure polylysine derivatives (Shi et al, 2015): (a) graft, (b) brush, (c) star architectures, (d) dendrimer, (e) hyperbranched, and (f) dendrigraft; (D) Self-assembled nanoparticles of PLL derivatives (Li Y. et al, 2020). antimicrobial spectrum, widen its application to fields, including food protection (Tuersuntuoheti et al, 2019), agriculture (Jiang et al, 2019;Rodrigues et al, 2020), and biomedical agents. Therefore, exploring the processing techniques and applications of EPL has attracted many concerns nowadays.…”

“…With great biocompatibility and controllable yet numerous compositions, polyamino-acid, which consists of several kinds of amino acid residues, exhibits attractive properties ( Graphical Abstract ). Among different types of polyamino-acids, poly-L-lysine (PLL) has earned considerable attention in recent years, showing great performances in several areas, not only including areas like food preservation (Tuersuntuoheti et al, 2019 ) and environmental pollution treatment (Kwon et al, 2017 ; Bucatariu et al, 2020 ) but also been widely used in medical applications (Shukla et al, 2012 ; Shi et al, 2015 ; Rodrigues et al, 2020 ). The structure of these kinds of polymers could vary, including cycle, dendritic, α-linear, and ε-linear ( Figure 1A ).…”

Snake venoms and purified toxins as biotechnological tools to control Ralstonia solanacearum

“…However, food production can be affected by several factors, including pathogen attacks on host plants. Overall, it is estimated that, for many crops, potential loss caused by pathogens can reach over 30% of agricultural production worldwide (Yuliar et al, 2015;Rodrigues et al, 2020).…”

“…In this scenario, natural/ synthetic antimicrobial molecules, as well as animal and vegetal biodiversity emerge as an immeasurable source of compounds with potential to control R. solanacearum strains. Some studies have shown that the essential oil extracted from Lantana camara and epsilon-poly-L-lysine (EPL), an antimicrobial peptide (AMP), inhibited bacteria growth (Cespedes et al, 2015;Mohamed et al, 2019;Rodrigues et al, 2020). These results can provide new antimicrobial substances, which are extremely important due to the current widespread of bacterial resistance (Datta et al, 2015).…”