Antibacterial peptides developed by researchers at Fraunhofer Institute in Germany have prevented the growth of bacteria, in this case Streptococcus mutans, which causes tooth decay. Image: Fraunhofer IZI
and more pathogens are becoming immune to antibiotics. Some bacteria
can no longer be combated. The World Health Organization WHO is warning
about resistance to drugs which were once so potent. The WHO’s
director-general Margaret Chan has pointed out that if measures are not
taken quickly, it may soon not be possible to treat many frequently
occurring infections. Figures released by the WHO show that in 2010
nearly half-a-million people were infected with a strain of tuberculosis
which is resistant to many antibiotics–one third of those infected
died. The Organization states that the growing spread of resistant
pathogens is attributable to the indiscriminate use of penicillin and
scientists at the Fraunhofer Institute for Cell Therapy and Immunology
IZI in Leipzig have found an alternative to the established antibiotics.
In the future, antimicrobial peptides will take up the battle against
have already identified 20 of these short chains of amino acids which
kill numerous microbes, including enterococci, yeasts and molds, as well
as human pathogenic bacteria such as Streptococcus mutans, which is
found in the human oral cavity and causes tooth decay. Even the
multi-resistant hospital bug Staphylococcus aureus is not immune, and in
our tests its growth was considerably inhibited,” says Dr. Andreas
Schubert, group manager at Fraunhofer IZI.
familiar fungicidal and bactericidal peptides the research scientists
produced sequence variations and tested them in vitro on various
microbes. Putrefactive bacteria, for example, were incubated for an hour
with the artificially produced antimicrobial peptides. As the new
peptides contain cationic amino acid residues, they can bond with the
negatively charged bacterial membrane and penetrate it. In their tests
the research scientists compared the survivability of the pathogens with
an untreated control. The experts focused on peptides with a length of
less than 20 amino acids.
peptides unlock their microbicidal effect within a few minutes. They
also work at a concentration of less than 1 µM, compared with
conventional antibiotics which require a concentration of 10 µM,” states
Schubert, summarizing the test results.
spectrum of efficacy of the tested peptides includes not only bacteria
and molds but also lipid-enveloped viruses. Another key factor is that
the peptides identified in our tests do not harm healthy body cells,“
the scientist explains.
food sector could also benefit from the antimicrobial peptides given
that the bacterial contamination of food products costs the industry
billions every year. Fresh lettuce and other salad greens, for example,
are badly contaminated by yeasts and molds. The shelf-life of foodstuffs
could be improved by adding antimicrobial peptides during the
is a definite possibility because the short-chain peptides tested
during the project do not exhibit any allergological risk on being added
to foodstuffs,” says Schubert.
company ÖHMI Analytic GmbH is the project partner in the development of
peptides for salad greens. The research scientist is convinced that
many possible applications exist, including in machinery manufacture –
for instance to keep hydraulic fluids free of microbes. As a next step
the expert and his team are going to test the antimicrobial peptides in vivo on infection models.