RESUMEN
We obtained a strain of Bacillus subtilis, which we named Czk1, from the aerial roots of rubber trees. This bacterial isolate exhibits strong antagonistic activity against Ganoderma pseudoferreum, Phellinus noxius, Helicobasidium compactum, Rigidoporus lignosus, Sphaerostilbe repens, and Colletotrichum gloeosporioides. Our earlier research has shown that the antagonistic activity of a fermentation supernatant Czk1 isolate produces a complex mixture of lipopeptides. In this study, we used methanol to extract crude lipopeptides, purified them using a Sephadex G-25 column, cloned the lipopeptide genes, and analyzed purified fractions by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) to identify the lipopeptides from B. subtilis strain Czk1. The cloned lipopeptide genes included those that encode the enzymes lpa, ituD, sfp, and fenB. The crude lipopeptides were purified and found in five fractions. Further analysis revealed that five fractions of the purified composition contained members of the surfactin, iturin, fengycin, and bacillomycin families of antibiotics. This suggests that these lipopeptides from strain Czk1 have potential as plant disease biocontrol agents.
Asunto(s)
Bacillus subtilis/metabolismo , Proteínas Bacterianas/metabolismo , Hevea/microbiología , Lipopéptidos/metabolismo , Raíces de Plantas/microbiología , Bacillus subtilis/genética , Bacillus subtilis/aislamiento & purificación , Proteínas Bacterianas/genética , Proteínas Bacterianas/aislamiento & purificación , Clonación Molecular , Colletotrichum/efectos de los fármacos , Colletotrichum/fisiología , Lipopéptidos/genética , Lipopéptidos/farmacología , Metanol , Péptidos Cíclicos/genética , Péptidos Cíclicos/metabolismo , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Esporas Fúngicas/efectos de los fármacos , Esporas Fúngicas/fisiologíaRESUMEN
The in vitro sensitivity of AvrPik allele isolates of Magnaporthe oryzae to isoprothiolane was examined and the virulence fitness costs of AvrPik allele isolates to isoprothiolane were assessed. Isoprothiolane was found to suppress the radial growth of AvrPik allele isolates at all concentrations (1, 5, 10, 15, and 20 µg/mL). Generally, a higher isoprothiolane concentration has a stronger inhibitory effect on mycelial growth in AvrPik allele isolates at 6 and 10 days after inoculation. The inhibitory effect of isoprothiolane also increased with treatment time. To determine whether a correlation existed between the in vitro sensitivity of AvrPik allele isolates and virulence, the half-maximal inhibitor concentration and 75% of the maximum inhibitor concentration were calculated for each mutation isolate and wild-type isolate. Based on these values and virulence, no significant correlation between the susceptibility of AvrPik allele isolates and virulence was detected. In summary, no fitness costs were associated with sensitivity of blast isolates carrying specific AvrPik alleles to different virulence.