Microbial Strain Collection

Bacterial secondary metabolites offer great potential for the discovery and development of leads in anti-infective research. One of the most promising ways for generating novel antibiotic scaffolds is the biodiversity guided expansion of existing microbial strain collections at the HZI. Although intensively studied, the actinomycetes, and the much less analyzed myxobacteria, are far from being exhausted as resources of novel chemistry. In fact, recent research has shown their enormous potential for future discoveries.

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During the last decades many pharmaceutical companies have terminated their antibiotic research activities and the general assumption that microorganisms exhibit only minor unexploited potential for discovering antibiotics.At the same time more and more of the so called “neglected” genera which were previously difficult to cultivate have become more accessible. Advanced and new methods make the screening and detection of their secondary metabolite profiles possible. New species can also be extracted from biological samples using new and uncommon isolation methods. 

Despite the tremendous developments originating from genomics, isolation of new genera and subsequent screening for the production of new metabolites is still the most successful way of finding novel antibiotic scaffolds that often exhibit new modes of action. The co-workers of the working group microbial strain collection are specialized on the different steps in this process for the detection of new active compounds from nature.

The microbial strain collection of the HZI has its focus on Myxobacteria and other uncommon microorganisms, especially rare Actinobacteria. Our myxobacterial strain collection comprises approximately 9500, the one of the Actinobacteria 3.000 strains. Many of the new isolates of the last years are coming from unusual habitas and from cooperation’s with working groups in many different countries. Within this isolates we found many novel species like Racemicystis persica, a species of the Myxobacteria isolated from an arid region in Iran. For the identification it was necessary to establish a polyphasic approach also for Myxobactaria, including additional physiological, chemotaxonomical and molecularbiological parameters.

Die novel isolates are cultivated under diverse conditions and are extracted. This extracts are used in a biological and chemical screening. Beside the novel isolates also the strains from the collection are studied in more detail. So it was found that the isolates that are identified as “Sorangium cellulosum” belong to a number of different species with total different secondary metabolite spectra. 

Although the isolation of novel species and families significantly increases the chances of the discovery of novel chemical entities, most of the already known and well described species also harbour a huge “hidden” biosynthetic potential in their genome. For the induction or enhancement of the production of these potential metabolites, our scientists diversify media compositions, work with chemical inductors and change the external cues and stress factors that influence secondary metabolite production.  

To screen the extract our scientists established a standardized process: They detect, identify and quantify the secondary metabolites in the extracts by using the coupling of a maXisTM UHR-TOF mass spectrometer with a fast UHPLC-chromatography. The combination of different analysing methods plays an important role in the characterization of unknown compounds.All information gained through biology and analytics is collected and stored in our in house database. In addition we continue the description of Actinobacteria in the characterization tool the Compendium, in collaboration with the German Culture Collection (DSMZ)

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