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.