Description:
<jats:title>ABSTRACT</jats:title>
<jats:p>
In this paper we report on the susceptibilities of a range of
<jats:italic>Bacillus</jats:italic>
species to the human antimicrobial peptide LL-37.
<jats:italic>B. subtilis</jats:italic>
showed a low level of resistance to killing by LL-37 (50% growth-inhibitory concentration [GI
<jats:sub>50</jats:sub>
], 1 μg/ml).
<jats:italic>B. cereus</jats:italic>
and
<jats:italic>B. thuringiensis</jats:italic>
showed intermediate levels of resistance to killing (GI
<jats:sub>50</jats:sub>
s, 33 μg/ml and 37 μg/ml, respectively).
<jats:italic>B. anthracis</jats:italic>
showed the highest level of resistance (GI
<jats:sub>50</jats:sub>
s, 40 to 66 μg/ml). The degradation of LL-37 by
<jats:italic>B. anthracis</jats:italic>
culture supernatant was blocked by the metalloprotease inhibitors EDTA and 1,10-phenanthroline, and the gene encoding the protease responsible for LL-37 degradation was not plasmid borne. Our findings suggest that alongside the classical plasmid-based virulence determinants, extracellular metalloproteases of
<jats:italic>B. anthracis</jats:italic>
may play a role in survival in the host.
</jats:p>