The measurement of gas produced as a fermentation end product in vitro was correlated with absorbance as a measure of bacterial growth and was used as a rapid screening procedure to test the antimicrobial activity of certain essential oil and tannin secondary plant metabolites on gastrointestinal microorganisms from chickens. The assay was optimised using Clostridium perfringens and Lactobacillus fermentum, and tested in antimicrobial assays against C. perfringens; the minimum inhibitory concentration for each essential oil and condensed tannin was determined. The effect of penicillin-G on C. perfringens, in both growth and fermentation assays, was similar, and for all secondary metabolites tested, concentrations that inhibited fermentation were also bacteriocidal. The assay was also used to demonstrate the effect of dietary composition and enzyme supplementation on fermentation of mixed gut microflora in vitro; results are compared with in vivo results for the same dietary treatments. The data demonstrate that the effects of bioactive secondary plant products and feed composition on individual organisms or mixed gut microflora can be tested by analysis of fermentative activity in vitro, and that this provides a rapid assay for testing potential poultry feed additives before in vivo trials.
Bibliographical noteFunding Information:
S. Shanmugavelu is grateful to The Malaysian Agricultural Research and Development Institute for financial assistance. G. Ruzickova and J. Zrustova acknowledge support from the Mendel University of Agriculture and Forestry in Brno, Czech Republic; G.R also thanks the Socrates programme, and J. Zrustova is grateful to the SAC Trust and GAÈR 523/03/H076 for providing support. The assistance of colleagues in obtaining performance data is also gratefully acknowledged. SAC receives funding from SEERAD.
- Clostridium perfringens
- Fermentation assay
- Gastrointestinal microflora