Growth and pectate-lyase activity of the ruminal bacterium Lachnospira multiparus in the presence of short-chain organic acids

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AimsAcetic, propionic, butyric and lactic acids are end products of feed fermentation by rumen microbes. The effects of these short chain acids on growth and pectate-lyase (PL) activity of Lachnospira multiparus were studied.Methods and ResultsThe bacterial strain used was L. multiparus D32. Acids were tested between 50 and 300 mmol l−1. Growth and PL activity were measured by the increase in total protein content and by the increase in absorbance at 235 nm in the reaction medium respectively. With the exception of lactic acid, all acids decreased bacterial growth rates; generally, these effects were more pronounced at higher concentrations and with acids of longer chains. PL activity was inhibited by all the acids except by butyric acid at 50 and 100 mmol l−1. Enzyme inhibition increased with the concentrations of the acids and lactic acid was the most inhibitory.ConclusionsHigh concentrations of short chain acids can differentially inhibit the growth rate and the PL activity of L. multiparus.Significance and Impact of the StudyProducts of fermentation generated by the ruminal microbiota could modify the degradation of pectic substances by this bacterium.

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