Plant-associated Pseudomonas bacteria are versatile producers of cyclic lipopeptides (CLPs), amphiphilic secondary metabolites with a broad range of biological activities. Some plant-associated Pseudomonas strains co-produce mycin and peptin-type CLPs with strong antimicrobial and/or phytotoxic activity without a clear-cut distinction between biocontrol strains and plant pathogens. The mycin-type CLPs have great potential as antimicrobials but are produced in very low quantities in lab conditions. This proposal focuses on understanding the complex regulation of mycins and peptins in two biocontrol strain and one plant pathogen hypothesizing that biocontrol strains produce these compounds in response to fungal signals, while plant pathogens respond to plant signals. To this end, knockout mutants in genes regulation mycin and peptin biosynthetis and promoter fusions will be
constructed to investigate which regulators and environmental signals activate the biosynthetic gene clusters. Based on this information culture conditions will be optimized. As an alternative strategy to boost CLP production, we intend to construct engineered strains using the “easy promoter activated compound identification approach” to boost the production of mycin and peptin-type CLPs. Pure compounds will be used to study biological activity, chemistry, structure-function analysis and synergistic effects in interactions with pathogens and the plant.