Abstract:
The chemical analysis of insect-associated Actinobacteria has attracted the interest of
natural product chemists in the past years as bacterial-produced metabolites are sought to be crucial
for sustaining and protecting the insect host. The objective of our study was to evaluate the phylogeny
and bioprospecting of Actinobacteria associated with fungus-growing termites. We characterized 97
Actinobacteria from the gut, exoskeleton, and fungus garden (comb) of the fungus-growing termite
Macrotermes natalensis and used two different bioassays to assess their general antimicrobial activity.
We selected two strains for chemical analysis and investigated the culture broth of the axenic strains
and fungus-actinobacterium co-cultures. From these studies, we identified the previously-reported
PKS-derived barceloneic acid A and the PKS-derived rubterolones. Analysis of culture broth yielded
a new dichlorinated diketopiperazine derivative and two new tetracyclic lanthipeptides, named
rubrominins A and B. The discussed natural products highlight that insect-associated Actinobacteria
are highly prolific natural product producers yielding important chemical scaffolds urgently needed
for future drug development programs.
