An inhibitory compound produced by a soil isolate of Rhodococcus has strong activity against the veterinary pathogen...

Area of Science:

• Microbiology
• Natural Product Chemistry
• Genomics

Background:

• The soil bacterium Rhodococcus, belonging to Actinobacteria, is an underexplored source of novel bioactive small molecules.
• Genome sequencing of Rhodococcus strains reveals numerous cryptic biosynthetic gene clusters, suggesting untapped metabolic potential.
• Recent interest focuses on Rhodococcus as a reservoir for new therapeutic compounds.

Purpose of the Study:

• To discover and characterize novel bioactive compounds from newly isolated Rhodococcus strains.
• To identify the genetic basis for the production of a potent inhibitory molecule from Rhodococcus strain MTM3W5.2.

Main Methods:

• Isolation and characterization of Rhodococcus strain MTM3W5.2.
• Bioactivity screening against various bacterial species.
• Identification of the biosynthetic gene cluster using random transposon mutagenesis.
• High-resolution mass spectrometry for compound identification.

Main Results:

• A potent inhibitory molecule was discovered from Rhodococcus strain MTM3W5.2.
• The molecule exhibits strong activity against Rhodococcus species, including Rhodococcus equi, and related genera, but not other bacteria.
• A large, multi-gene cluster containing 14 type I polyketide synthase genes was identified as essential for compound production.
• Mass spectrometry confirmed the presence of a compound at m/z 911.5490 in the producing strain.

Conclusions:

• Rhodococcus strain MTM3W5.2 produces a unique, antibiotic-like compound.
• The identified gene cluster provides insight into the biosynthesis of this novel molecule.
• This discovery underscores Rhodococcus as a promising source for new bioactive natural products.