Applied Microbiology

Many bacteria are able to generate resistances against antibiotics leading to an uncontrolled spreading of pathogenic strains.However, an efficient treatment of numerous diseases is missing due to the lack of specific drugs. Despite intensive world-wide efforts using alternative strategies based on synthetic chemistry, the exploitation of biologically active natural products as candidates for anti infective drugs is still the most promising approach. The majority of the medically important antibiotic drugs are derived from secondary metabolites, which are produced by bacteria and fungi. In addition to the wellstudied, highly productive actinobacteria, myxobacteria are a further rich source for new antibiotics. To date more than 100

new metabolites and more than 500 derivatives were described from these soil dwelling, predatory microorganisms. In the past it turns out that in particular new families, genera andspeciesofmyxobacteria are reliable sources for new bioactive compounds. Promising sources for the isolation of new myxobacteria are uncommon habitats like moors (peat bogs and fen), characterized by low pH values. Moors have been neglected with regard to the isolation of myxobacteria in the past. In our study, the diversity of myxobacteria in peat bogs and fen samples from the Harz-region, Germany, was evaluated by enhanced standard cultivation methods as well as by cultivation independent 16S rDNA clone bank analyses. Therefore a total of 278

clone sequences, sequences of 24 cultures isolated from moor within this study as well as sequences from the next relatives (NCBI) were added to a phylogenetic tree which in addition contains all myxobacterial type strains. The phylogenetic analysis revealed that the cultivated strains exclusively belong to the genus Corallococcus and that the majority of clone sequences represents unknown myxobacteria which could not be acquired by cultivation so far. In addition, most of our clone bank sequences are exclusively related to other, also uncultivated myxobacteria, which to a large extant came from studies about acidic soils, too. These results are in accordance with our preliminary comparative study about the diversity of myxobacteria in Kiritimati Island and German compost which also revealed significant discrepancies between the diversity of cultivable

myxobacteria and those exclusively detectable with cultivation-independent methods. Both studies have shown that there is a strong need to develop new and innovative isolation techniques to reach the numerous groups of myxobacteria which resist cultivation approaches. Especially uncommon habitats like moors, but also classical habitats like compost consist of numerous unknown myxobacterial species, genera and even families which in turn harbor a great potential of urgently needed, new

antibiotics.