Pseudophomins A–D Produced from Pseudomonas sp. HN8‑3 Using an OSMAC Approach and Their Roles in Biocontrol of Phytophthora capsici in Cucumbers

In this study, two new cyclic lipopeptides (CLPs) pseudophomins
C (3) and D (4) and two known CLPs pseudophomins
A (1) and B (2) were produced and characterized
from the bacterial supernatant of Pseudomonas sp. HN8-3 by an OSMAC (one strain-many compounds) approach. OSMAC
is a strategy that involves feeding of a single microorganism with
divergent substrates to stimulate the production of new secondary
metabolites. These pseudophomins were purified and identified via
chromatographic methods, droplet collapse assay, genome mining, spectroscopic
and spectrometric analyses, and single-crystal X-ray diffraction (XRD).
Moreover, bioactivity tests showed that pseudophomins could lyse the
zoospores of Phytophthora capsici in
vitro, and coapplication of pseudophomins with zoospores of P. capsici further reduced the incidence of P. capsici on cucumber leaves. Collectively, these
results indicated that pseudophomins have the potential to be developed
as biopesticides for controlling P. capsici in cucumber.