Process
Antibiotic Interactions in Ethanol Production:
Sharing a Decade of Data Evidence shows that effective drug combinations decrease the risk of bacterial contamination and antimicrobial resistance. By Jenny Forbes and Cam Fowler
Recently, producers have asked Phibro Ethanol questions about antibiotic interactions. Ethanol producers want to know: Do drugs such as virginiamycin and penicillin work in synergy or do they have an antagonistic relationship? Is there a technical risk to using these drugs in combination day in and day out? In other words, are our historic practices damaging? The available information overwhelmingly demonstrates that the antimicrobial activities of virginiamycin and penicillin work well together. Specifically, evidence shows that effective drug combinations decrease the risk of bacterial contamination and antimicrobial resistance. Understanding Drug Interactions Although the fields of human and animal medicine spend significant energy researching drug interactions (including antibiotic interactions), little research has been conducted specific to industrial applications. That said, medical research finds that drugs commonly used to treat infections and chronic disease in humans and animals often have negative (antagonistic) or positive (synergistic) effects when combined. Indeed, it is commonly accepted that antibiotics frequently interact, but few studies have been done comparing treatment interactions in commercial ethanol plants. Despite the unknowns, ethanol producers often treat fermentations with virginiamycin, penicillin, or blends of these two antibiotics. Virginiamycin is a streptogramin type of antibiotic that inhibits the 50S ribosomal subunit of bacteria. Inhibiting the 50S ribosomal subunit interferes with protein synthesis and stops bacterial growth (referred to as (R) throughout the article). In contrast, penicillin is a beta-lactam antibiotic. Penicillin and antibiotics in the beta-lactam class work by interfering with bacterial cell wall production, often resulting in bacterial lysis and death (referred to as (W) throughout the article). To address whether it’s safe or helpful to combine antibiotics in fermentation, this article will summarize data from scientific technical journals and present data generated in Phibro’s laboratory over the last decade. A number of independent, peer-reviewed technical studies indicate that combining drugs similar to virginiamycin and penicillin have a neutral to synergistic effect. Phibro’s
FIGURE 1: Adapted from Yeh P., et. al.1 demonstrating a synergistic drug interaction between cell wall inhibitors and 50S ribosome inhibitors.
FIGURE 2: Adapted from Yeh P., et. al.1 showing pairwise interactions between cell wall inhibitors (Drug X) and 50S ribosome inhibitors (Drug Y).
CONTRIBUTION: The claims and statements made in this article belong exclusively to the author(s) and do not necessarily reflect the views of Ethanol Producer Magazine or its advertisers. All questions pertaining to this article should be directed to the author(s).
34 | ETHANOL PRODUCER MAGAZINE | DECEMBER 2021
