Cyclic lipopeptide profile of the plant-beneficial endophytic bacterium Bacillus subtilis HC8

Abstract

In a previous study (Malfanova et al. in Microbial Biotech 4:523–532, 2011), we described the isolation and partial characterization of the biocontrol endophytic bacterium B. subtilis HC8. Using thin-layer chromatography, we have detected several bioactive antifungal compounds in the methanolic extract from the acid-precipitated supernatant of HC8. In the present study, we have further analyzed this methanolic extract using liquid chromatography-mass spectrometry. Based on the comparison of retention times and molecular masses with those of known antifungal compounds, we identified three families of lipopeptide antibiotics. These include four iturins A having fatty acyl chain lengths of C14 to C17, eight fengycins A (from C14 to C18 and from C15 to C17 containing a double bond in the acyl chain), four fengycins B (C15 to C18), and five surfactins (C12 to C16). Evaluation of the antifungal activity of the isolated lipopeptides showed that fengycins are the most active ones. To our knowledge, this is the first report of an endophytic Bacillus subtilis producing all three major families of lipopeptide antibiotics containing a very heterogeneous mixture of homologues. The questions remain open which of these lipopeptides (1) are being produced during interaction with the plant and (2) are contributing to the biocontrol activity of HC8.

Genetic, physiological and biochemical characterization of Bacillus sp . strain RMB7 exhibiting plant growth promoting and broad spectrum antifungal activities

“…Bacillus subtilis is a common soil and rhizosphere resident bacteria having dual beneficial properties of plant growth promotion as well as biocontrol activities [11,12]. Almost 5% of its genome is devoted for the production of antibiotics and many strains from this genus have shown the potential to produce about two dozen structurally diverse antimicrobial compounds [11][12][13]. Most active and useful among these compounds are the cyclic lipopeptides of three families: surfactin, iturin and fengycin.…”

Microbial secondary metabolites ameliorate growth, in planta contents and lignification in Withania somnifera (L.) Dunal

“…Tarkka and Hampp (2008) and Prapagdee et al (2008) reported the role of extracellular secondary metabolites of soil bacterium Streptomycetes in biotic interaction with the host plants. Likewise, the compounds mycosubtilin, rhizocticins, antifungal phosphonate oligopeptides and cyclic lipopeptide produced by different strains of B. subtilis enhanced the organism's antagonistic and plant growth promotion activities (Leclère et al 2005;Borisova et al 2010;Malfanova et al 2012). Vinale et al (2008) reported Trichoderma species to be well known producers of compounds that substantially affect the metabolism of the plant.…”

Research Progress in Lipopeptide Biosurfactants

“…The composition of amino acids in the molecule is determined by paper chromatography and automatic amino acid analyzer. Methyl esterification is conducted first before fatty acid structure measurement, followed by research with NMR (Nuclear Magnetic Resonance) and mass spectrometry instruments [10,11].…”

“…Lipopeptides were eluted using a two component solvent system of which solvent A is water and solvent B is acetonitrile, both acidified with 0.1% formic acid. We used four different elution programs including one general program to elute all lipopeptides and three family-specific programs to get a better separation and quantification of the different lipopeptides within each family [10].…”