Antagonistic and protective activity of Lactobacillus plantarum strain 17M against E. amylovora.

Abstract

The subject of the study was to identify the antagonism of the Lactobacillus plantarum strain 17M against the causative agent of fire blight, the bacterium Erwinia amylovora, and to evaluate its protective capabilities on apple blossoms against this disease. For comparison 9 strains of lactic acid bacteria from the LLP "SPC of Microbiology and Virology" collection were included in the study. Strain 17M appeared to be superior in limiting the growth of the pathogen on all 3 liquid media tested. Its maximum inhibitory activity was proved on MRS Broth medium. The analysis of the secondary metabolites produced by strain 17M in liquid medium revealed that it consisted mainly of acetic acid (53.2 ± 4.3%), lactic acid (16.3 ± 2.3%) and 2,3-butanedione (14.84 ± 4.1%). The presence of other organic compounds was also detected but in a smaller amount. Study on influence of those compounds on growth of E. amylovora showed that lactic acid at concentration of 5% showed inhibitory activity but it was not toxic to apple flowers. The effectiveness of strain 17M culture liquid diluted with sterile water and added to E. amylovora inoculum at 10% or 20% was 76.7 ± 5.8% and 88.3 ± 12.6%, respectively. This study confirms the potential use of strain 17M as an active microbial agent to combat fire blight of fruit crops in Kazakhstan.