virginiamycin is used in the fuel ethanol industry to prevent microbial contamination. virginiamycin is a streptogramin antibiotic similar to pristinamycin and quinupristin/dalfopristin. it is a combination of pristinamycin iia and virginiamycin s1. virginiamycin is used in the fuel ethanol industry to prevent microbial contamination. virginiamycin inhibits protein synthesis by binding to the 23s ribosomal subunit and blocking the translation process, with no effect on transcription. it is not commonly used to treat bacterial infections in domestic animals despite possessing a broad-spectrum antimicrobial activity.