Assessment of potential anti-methanogenic and antimicrobial activity of ethyl nitroacetate, a-lipoic acid, taurine and l-cysteinesulfinic acid in vitro

Authors: LEVENT, GIZEM - Texas Tech University; BOZIC, ALEKSANDAR - University Of Novi Sad; PETRUJKIC, BRANKO - University Of Belgrade; CALLAWAY, TODD - University Of Georgia; Poole, Toni; Crippen, Tawni - Tc; Harvey, Roger; OCHOA-GARCIA, PEDRO - Universidad Autonoma De Chihuahua; CORRAL-LUNA, AGUSTIN - Universidad Autonoma De Chihuahua; Anderson, Robin; Yeater, Kathleen

Submitted to: Microorganisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2023
Publication Date: 12/23/2023
Citation: Levent, G., Bozic, A., Petrujkic, B.T., Callaway, T.R., Poole, T.L., Crippen, T.L., Harvey, R.B., Ochoa-Garcia, P., Corral-Luna, A., Anderson, R.C., Yeater, K.M. 2023. Assessment of potential anti-methanogenic and antimicrobial activity of ethyl nitroacetate, a-lipoic acid, taurine and l-cysteinesulfinic acid in vitro. Microorganisms. 12(1). Article 34. https://doi.org/10.3390/microorganisms12010034.
DOI: https://doi.org/10.3390/microorganisms12010034

Interpretive Summary: Livestock producers need new technologies to maintain optimal health and well-being in their animals while minimizing the risks of propagating and disseminating antimicrobial-resistant bacteria to humans or other animals. Where possible, these interventions should contribute to the efficiency and profitability of animal production to avoid passing costs on to consumers. In this study we examined a selection of potential inhibitors of rumen methane production, a digestive inefficiency that results in the loss of up to 12% of the host's dietary energy intake. Methane is also a potent greenhouse gas. The potential methane inhobitors were tested for their activity against Escherichia coli O157:H7 and Salmonella Typhimurium DT104. Ethyl nitroacetate decreased the growth rates of these bacteria by 16 to 36% when compared to untreated controls. Growth rates of these pathogens were also decreased by 31 to 93% by alpha-lipoic acid, which we also found to inhibit in vitro rumen methanogenesis up to 66%. Various other oxidized nitro and organosulfur compounds were neither antimicrobial nor anti-methanogenic in the present study. These results may provide livestock producers with a feed strategy to reduce emissions of the potent greenhouse gas, methane, while also improving the gastrointestinal health of their animals. Ultimately, this technology may help livestock producers produce safer meat and milk for the American consumer while contributing to a cleaner environment.

Technical Abstract: Livestock producers need new technologies to maintain optimal health and well-being in their animals while minimizing the risks of propagating and disseminating antimicrobial-resistant bacteria to humans or other animals. Where possible, these interventions should contribute to the efficiency and profitability of animal production to avoid passing costs on to consumers. In this study we examined a selection of potential inhibitors rumen methane production, a digestive inefficiency that results in the loss of up to 12% of the host's dietary energy intake and produces a potent greenhouse gas for their activity against Escherichia coli O157:H7 and Salmonella Typhimurium DT104. When tested against anaerobically grown O157:H7 and DT104, the methanogenic inhibitor ethyl nitroacetate at concentrations of 3 and 9 mM decreased the mean specific growth rates of O157:H7 by 22 to 36% and of DT104 by 16 to 26% when compared to controls (0.823 and 0.886 h**-1, respectively). Growth rates of O157:H7 and DT104 were decreased from controls by 31 to 93% and by 41 to 78% by alpha-lipoic acid, which we also found to inhibit in vitro rumen methanogenesis up to 66%. Ethyl nitroacetate was mainly bacteriostatic whereas 9 mM alpha-lipoic acid decreased maximal optical densities (measured at 600 nm) of O157:H7 and DT104 by 25 and 42% compared to controls (0.448 and 0.451, respectively). Various other oxidized nitro and organosulfur compounds were neither antimicrobial nor anti-methanogenic activity in the present study.