Variations in the ability of ruminal gram-negative Prevotella species to resist monensin

Area of Science:

• * Rumen microbiology
• * Animal nutrition
• * Antimicrobial resistance

Background:

• * Monensin is a feed additive used to modulate rumen fermentation.
• * Prevotella species are key inhabitants of the rumen microbiome.
• * Understanding monensin sensitivity in Prevotella is crucial for optimizing its use in livestock.

Purpose of the Study:

• * To quantify the range of monensin sensitivity among Gram-negative ruminal Prevotella strains.
• * To investigate the relationship between monensin exposure, adaptation, and cellular responses.
• * To explore potassium depletion as a reliable indicator of monensin sensitivity.

Main Methods:

• * Growth experiments were conducted with 15 Prevotella strains exposed to varying monensin concentrations.
• * Monensin adaptation was achieved through repeated exposure to sublethal doses.
• * Potassium efflux from energized washed cell preparations was measured using monensin challenge.

Main Results:

• * A 2000-fold difference in monensin sensitivity was observed across Prevotella strains.
• * Prevotella bryantii B(1)4 demonstrated significantly higher tolerance (up to 20 microM) compared to P. ruminicola strains (≤0.01 microM).
• * Potassium depletion correlated strongly with monensin sensitivity, with adapted P. bryantii B(1)4 showing a higher K(d) and lower K(max).

Conclusions:

• * Ruminal Prevotella strains display a wide spectrum of monensin sensitivity, with P. bryantii B(1)4 being an outlier.
• * Monensin adaptation can increase tolerance, but the underlying mechanisms differ among strains.
• * Potassium depletion serves as a robust physiological marker for assessing monensin sensitivity in Prevotella species.