Biocontrol Ability of Lysobacter antibioticus HS124 Against Phytophthora Blight Is Mediated by the Production of 4-Hydroxyphenylacetic Acid and Several Lytic Enzymes

Abstract

Several rhizobacteria play a vital role in plant protection, plant growth promotion and the improvement of soil health. In this study, we have isolated a strain of Lysobacter antibioticus HS124 from rhizosphere and demonstrate its antifungal activity against various pathogens including Phytophthora capsici, a destructive pathogen of pepper plants. L. antibioticus HS124 produced lytic enzymes such as chitinase, beta-1,3-glucanase, lipase, protease, and an antibiotic compound. This antibiotic compound was purified by diaion HP-20, silica gel, sephadex LH-20 column chromatography and high performance liquid chromatography. The purified compound was identified as 4-hydroxyphenylacetic acid by gas chromatography-electron ionization (GC-EI) and gas chromatography-chemical ionization (GC-CI) mass spectrometry. This antibiotic exhibited destructive activity toward P. capsici hyphae. In vivo experiments utilizing green house grown pepper plants demonstrated the protective effect of L. antibioticus HS124 against P. capsici. The growth of pepper plants treated with L. antibioticus culture was enhanced, resulting in greater protection from fungal disease. Optimum growth and protection was found when cultures were grown in presence of Fe(III). Additionally, the activities of pathogenesis-related proteins such as chitinase and beta-1,3-glucanase decreased in roots, but increased in leaves with time after treatment compared to controls. Our results demonstrate L. antibioticus HS124 as a promising candidate for biocontrol of P. capsici in pepper plants.

Morphology and Biochemistry of Microbial Antagonists and Their Effect in the Growth of Garbanzo and Control of Fusariosis

“…El crecimiento radial de las colonias de antagonistas y fitopatógeno se midió cada 24 h, realizando las observaciones hasta los diez de post-incubación. La capacidad antagónica por antibiosis de las cepas ensayadas fue evaluada a los siete días de post-inoculación, mediante el Porcentaje de Inhibición del Crecimiento Radial (PICR), empleando la fórmula propuesta por [32], PICR = [(R1 − R2)/100]; donde, PICR fue el porcentaje de inhibición en el crecimiento del micelio del fitopatógeno; R1 fue el crecimiento de la colonia del patógeno-testigo; y R2 el crecimiento radial de la colonia del patógeno en confrontación en cultivo dual.…”

Draft Genome Sequence of a Chitinase-Producing Biocontrol Bacterium, Lysobacter antibioticus HS124

“…They produce a variety of extracellular enzymes and antibiotic compounds, most of which await structurally identification. Lysobacter antibioticus HS124 was isolated from Naju rhizosphere in Korea based on its ability to solubilize chitin and antagonism of growth of phytopathogens, including Phytophthora capsici and Rhizoctonia solani (Ko et al, 2009;2011). The isolate has insecticidal activity against the diamondback moth (Kang et al, 2010).…”

“…Unique genes encoding a chitinase and microbial collagenase were identified, enzymes with potential roles in biocontrol activity. Other genes related to biocontrol activity encoded the enzymes, chitinosanase, cellulase, protease and gelatinase (Ko et al, 2009). Although biosurfactants, such as cyclic depsipeptides and cyclic lipopeptides made by nonribosomal synthesis, are produced by other Lysobacter (Xie et al, 2012), the draft genome sequence did not show genes encoding such synthases.…”

“…The isolate has insecticidal activity against the diamondback moth (Kang et al, 2010). Production of a novel antifungal compound, 4-hydroxyphenylacetic acid, and several lytic enzymes are proposed to be important in its biocontrol against Phytophthora blight (Ko et al, 2009).…”

Effect of Gelatinase and Chitinase Producing Microorganism on the Growth of Soybean and Control of Stink Bug in Field

“…Plant growth-promoting bacteria are associated with many plant species and are commonly present in many environments . The active mechanisms of microbial biocontrol agents against plant pathogens include lytic activity , direct antibiosis (Ko et al, 2009), hyperparasitism (Lee et al, 2004), induction of resistance (Lee, 1997), and competition for space and nutrients (Jung et al, 2006). Some microorganisms act as plant growth promoting rhizobacteria (PGPR) that fix nitrogen (N), solubilize phosphorus (P), chelate iron (Fe), produce hormone-like substances, and degrade 1-aminocyclopropane-1-carboxylate (ACC) deaminase in soil (Jung et al, 2007;Kim et al, 2011).…”