Characterisation of Lysobacter enzymogenes ( Christensen and Cook 1978) strain 3.1 T8, a powerful antagonist of fungal diseases of cucumber

摘要

Isolate 3.1T8 of Lysobacter enzymogenes (Christensen and Cook 1978), originating from the rhizosphere of cucumber and shown to have the potential to control Pythium aphanidermatum, is described. The strain produces extracellular proteases and lipases and shows high levels of resistance against streptomycin, kanamycin and tetracycline, but not to chloramphenicol. It shows strong in vitro antibiosis against P. aphanidermatum and several other phytopathogenic fungi. In order to identify the isolate, a carbon substrate oxidation profile (Biolog) was generated, and fatty acid methyl ester (FAME) analysis was performed. Also, the 16S rRNA gene was cloned and sequenced. With Biolog and FAME analysis, no assignment to species level was possible, because the species was not in the respective databases. BLAST analysis of the obtained sequence, followed by phylogenetic analysis, using a number of related and unrelated sequences, showed that the isolate was most closely related to Lysobacter enzymogenes (Christensen and Cook 1978). [KEYWORDS: biocontrol ; Lysobacter enzymogenes ; Pythium spp. ; soilless systems]