Description:
<jats:title>ABSTRACT</jats:title>
<jats:p>
The spore-forming bacterium
<jats:named-content content-type="genus-species">Paenibacillus larvae</jats:named-content>
causes a severe and highly infective bee disease, American foulbrood (AFB). Despite the large economic losses induced by AFB, the virulence factors produced by
<jats:named-content content-type="genus-species">P. larvae</jats:named-content>
are as yet unknown. To identify such virulence factors, we experimentally infected young, susceptible larvae of the honeybee,
<jats:named-content content-type="genus-species">Apis mellifera carnica</jats:named-content>
, with different
<jats:named-content content-type="genus-species">P. larvae</jats:named-content>
isolates. Honeybee larvae were reared
<jats:italic>in vitro</jats:italic>
in 24-well plates in the laboratory after isolation from the brood comb. We identified genotype-specific differences in the etiopathology of AFB between the tested isolates of
<jats:named-content content-type="genus-species">P. larvae</jats:named-content>
, which were revealed by differences in the median lethal times. Furthermore, we confirmed that extracts of
<jats:named-content content-type="genus-species">P. larvae</jats:named-content>
cultures contain low-molecular-weight compounds, which are toxic to honeybee larvae. Our data indicate that
<jats:named-content content-type="genus-species">P. larvae</jats:named-content>
secretes metabolites into the medium with a potent honeybee toxic activity pointing to a novel pathogenic factor(s) of
<jats:named-content content-type="genus-species">P. larvae</jats:named-content>
. Genome mining of
<jats:named-content content-type="genus-species">P. larvae</jats:named-content>
subsp.
<jats:named-content content-type="genus-species">larvae</jats:named-content>
BRL-230010 led to the identification of several biosynthesis gene clusters putatively involved in natural product biosynthesis, highlighting the potential of
<jats:named-content content-type="genus-species">P. larvae</jats:named-content>
to produce such compounds.
</jats:p>