Beschreibung:
<jats:title>ABSTRACT</jats:title>
<jats:p>
Immobilization and magnetic separation for specific enrichment of microbial cells, such as the pathogen
<jats:italic>Listeria monocytogenes</jats:italic>
, depends on the availability of suitable affinity molecules. We report here a novel concept for the immobilization and separation of bacterial cells by replacing antibodies with cell wall-binding domains (CBDs) of bacteriophage-encoded peptidoglycan hydrolases (endolysins). These polypeptide modules very specifically recognize and bind to ligands on the gram-positive cell wall with high affinity. With paramagnetic beads coated with recombinant
<jats:italic>Listeria</jats:italic>
phage endolysin-derived CBD molecules, more than 90% of the viable
<jats:italic>L. monocytogenes</jats:italic>
cells could be immobilized and recovered from diluted suspensions within 20 to 40 min. Recovery rates were similar for different species and serovars of
<jats:italic>Listeria</jats:italic>
and were not affected by the presence of other microorganisms. The CBD-based magnetic separation (CBD-MS) procedure was evaluated for capture and detection of
<jats:italic>L. monocytogenes</jats:italic>
from artificially and naturally contaminated food samples. The CBD separation method was shown to be superior to the established standard procedures; it required less time (48 h versus 96 h) and was the more sensitive method. Furthermore, the generalizability of the CBD-MS approach was demonstrated by using specific phage-encoded CBDs specifically recognizing
<jats:italic>Bacillus cereus</jats:italic>
and
<jats:italic>Clostridium perfringens</jats:italic>
cells, respectively. Altogether, CBD polypeptides represent novel and innovative tools for the binding and capture of bacterial cells, with many possible applications in microbiology and diagnostics.
</jats:p>