Characterization ofBacillusstrains from apple and pear trees in South Africa antagonistic toErwinia amylovora

Abstract

In order to find reasons for the absence of fire blight in most countries of the Southern hemisphere, bark samples from apple and pear trees in orchards of the Western Cape region in South Africa were extracted for bacteria which could be antagonistic to Erwinia amylovora. Screening was done in the late growth season and mainly Gram-positive bacteria were isolated. Approximately half of them produced growth inhibition zones on a lawn of E. amylovora. Most isolates were classified as Bacillus megaterium by microbiological assays and in API 50 test systems. They were visualized in the light microscope as non-motile large rods. These strains may not be responsible for the absence of fire blight in orchards, but they may indicate unfavourable climatic conditions for Gram-negative bacteria including E. amylovora. They may reduce the ability of E. amylovora to establish fire blight and could also be useful for application in biological disease control.

Plant growth-promoting activities and genomic analysis of the stress-resistant Bacillus megaterium STB1, a bacterium of agricultural and biotechnological interest

“…Altogether, these results are in agreement with reports indicating the antagonistic activities and production of antifungal and antibacterial compounds by B. megaterium strains [5,[55], [56], [57]].…”

Assessment of the Antimicrobial Activity and the Entomocidal Potential of Bacillus thuringiensis Isolates from Algeria

“…This reflected a wide range of antibacterial molecules synthetized by these B. thuringiensis isolates, which could be further used in the control of some pathogenic and/or phytopathogenic diseases. It would be interesting to survey those isolates against some phytopathogenic bacteria causing serious losses in fruits and vegetables in Algeria, such as Erwinia amylovora and Erwinia carotovora [80,81]. In 2012, Djenane [82] investigated 97 isolates of Bacillus spp.…”

Bacterial Quorum-Quenching Lactonase Hydrolyzes Fungal Mycotoxin and Reduces Pathogenicity of Penicillium expansum—Suggesting a Mechanism of Bacterial Antagonism

“…Towards the understanding of the involvement of lactonase activity with an ecological relevant bacteria in degrading fungal mycotoxins in the apple microbiome, the sequence of AiiA from Bacillus thuringiensis (WP_000216581.1) was used similarly to identify putative lactonases from bacteria that reside in apple trees, such as in Bacillus megaterium (basionym: Priestia megaterium). B. megaterium was identified in bark samples from apple and pear orchards and was suggested to be antagonistic to the AHL-producing pathogen Erwinia amylovora E. amylovora) [66]. Indeed, a homolog sharing 96% identity was identified, with the accession number ACX55098.1 annotated as AHL lactonase by NCBI.…”