A total of 11 ruminal strains currently assigned to Butyrivibrio fibrisolvens and Pseudobutyrivibrio xylanivorans were cultivated in two different media, rumen fluid containing M2 and short-chain fatty acid (SCFA) containing M330, and their cellular fatty acid methyl esters (FAME) and dimethylacetals (DMA) were analyzed using gas chromatography. A comparison of the FAME/DMA compositions revealed that the difference in SCFA contents in the growth medium induced a pronounced quantitative effect on the cellular branched-chain fatty acid and aldehydes proportions only in the P. xylanivorans strains. This study shows that FAME/DMA analysis is a powerful chemotaxonomic tool in the group of phenotypically similar rumen butyrivibria especially when the influence of the growth medium is evaluated. Skupno smo gojili 11 vampnih sevov iz vrst Butyrivibrio fibrisolvens in Pseudobutyrivibrio xylanivorans v dveh različnih gojiščih: v M2 z vampnim sokom in v M330 z mešanico kratkoverižnih maščobnih kislin (SCFA). S plinsko kromatografijo smo analizirali njihove metilne estre celičnih maščobnih kislin (FAME) in dimetilacetale (DMA). Primerjava sestave FAME/ DMA je razkrila, da razlika v vsebnosti SCFA v gojišču povzroči izrazit kvantitativen učinek na deleže celičnih razvejanih maščobnih kislin in aldehidov le pri sevih vrste P. xylanivorans. Naša raziskava dokazuje, da lahko FAME/DMA analizo učinkovito uporabljamo v kemotaksonomiji fenotipsko podobnih butirivibrijev z ustreznim ovrednotenjem vpliva gojišča.