Cenek Novotny
Institute of Microbiology of the CAS, Czech Republic
Title: Antagonistic effect of bacteria and fungi on Fusarium wilt pathogen
Biography
Biography: Cenek Novotny
Abstract
Biocontrol agents represent an alternative to chemicals in the management of fungal crop diseases. A wide range of microorganisms can be used as biocontrol agents, mainly bacterial and fungal isolates and the biological control results from many types of interactions between organisms. In our study, Fusarium oxysporum f.sp. conglutinans was confronted with three different biocontrol agents, Trichoderma harzianum, Bacillus amyloliquefaciens and Pseudomonas aeruginosa in dual cultures. Bioassays and metabolites produced in the microbial interactions were screened by a Matrix-Assisted, Laser Desorption/Ionization (MALDI) mass spectrometry. T. harzianum exhibited the strongest inhibition of mycelial growth of F. oxysporum by overgrowing the pathogen in the later stages of co-cultivation. The metabolite profiles obtained in the case of T. harzianum and B. amyloliquefaciens were the result of an attack on the F. oxysporum mycelium by the antagonists by means of membrane-attacking peptaibols and a number of antimicrobial lipopeptides and siderophores, respectively. The biocontrol activity of T. harzianum and B. amyloliquefaciens consisted in their ability to suppress the production of mycotoxin beauvericin by F. oxysporum. In the case of P. aeruginosa, siderophores pyoverdine E/D and two rhamnolipids were produced as major bacterial metabolites. Under the conditions of a co-culture with F. oxysporum the production of rhamnolipides by the bacterium was blocked by the action of the fungal phytopathogen. The biocontrol of F. oxysporum by P. aeruginosa was weaker that those by T. harzianum and B. amyloliquefaciens.