Diversity of Antibiotic-Active Bacteria Associated with the Brown Alga Laminaria saccharina from the Baltic Sea

Bacteria associated with the marine macroalga Laminaria saccharina, collected from the Kiel Fjord (Baltic Sea, Germany), were isolated and tested for antimicrobial activity. From a total of 210 isolates, 103 strains inhibited the growth of at least one microorganism from the test panel including Gram-negative and Gram-positive bacteria as well as a yeast. Most common profiles were the inhibition of Bacillus subtilis only (30%), B. subtilis and Staphylococcus lentus (25%), and B. subtilis, S. lentus, and Candida albicans (11%). In summary, the antibiotic-active isolates covered 15 different activity patterns suggesting various modes of action. On the basis of 16S rRNA gene sequence similarities >99%, 45 phylotypes were defined, which were classified into 21 genera belonging to Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. Phylogenetic analysis of 16S rRNA gene sequences revealed that four isolates possibly represent novel species or even genera. In conclusion, L. saccharina represents a promising source for the isolation of new bacterial taxa and antimicrobially active bacteria

Methods for isolation of marine-derived endophytic fungi and their bioactive secondary products

Marine-derived fungi have been shown in recent years to produce a plethora of new bioactive secondary metabolites, some of them featuring new carbon frameworks hitherto unprecedented in nature. These compounds are of interest as new lead structures for medicine as well as for plant protection. The aim of this protocol is to give a detailed description of methods useful for the isolation and cultivation of fungi associated with various marine organisms (sponges, algae and mangrove plants) for the extraction, characterization and structure elucidation of biologically active secondary metabolites produced by these marine-derived endophytic fungi, and for the preliminary evaluation of their pharmacological properties based on rapid 'in house' screening systems. Some results exemplifying the positive outcomes of the protocol are given at the end. From sampling in marine environment to completion of the structure elucidation and bioactivity screening, a period of at least 3 months has to be scheduled