Agriculture and Agri-Food Canada

About: Agriculture and Agri-Food Canada is a facility organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Population & Soil water. The organization has 10921 authors who have published 21332 publications receiving 748193 citations. The organization is also known as: Department of Agriculture and Agri-Food.

Effect of steroidal saponin from Yucca schidigera extract on ruminal microbes.

Abstract: The effects of steroidal saponins (SAP) isolated from Yucca schidigera extract on ruminal bacteria and fungi were investigated in pure culture studies. Prevotella bryantii, Ruminobacter amylophilus, Selenomonas ruminantium and Streptococcus bovis were cultured through ten 24-h transfers in ruminal fluid medium containing 0 or 25 µg SAP ml−1 (measured as smilagenin equivalents). The four strains, each non-exposed or pre-exposed to SAP, were then inoculated into medium containing 0 or 250 µg smilagenin equivalents ml−1 and 24-h growth curves were determined. The cellulolytic ruminal bacteria Ruminococcus flavefaciens, Fibrobacter succinogenes and Rc. albus were cultured for 72 h on Whatman no. 1 filter paper in medium containing 0, 9, 90 or 180 µg SAP ml−1 for the determination of filter paper digestion and endoglucanase activity. The ruminal bacteria differed in their responses to SAP. Steroidal saponins in the medium reduced the growth of Strep. bovis (P 0·05) between pre-exposed and non-exposed cultures and the concentrations of total SAP and soluble (deglycosylated) SAP in the liquid fraction were unchanged (P > 0·05) over time. Steroidal saponins inhibited the digestion of filter paper by all three cellulolytic bacteria, but F. succinogenes was less (P < 0·05) sensitive to SAP and more (P < 0·05) effective at deglycosylating SAP than were Rc. flavefaciens or Rc. albus. Transmission electron microscopy revealed that SAP altered the cell walls of the SAP-inhibited non-cellulolytic bacteria. The ruminal fungi, Neocallimastix frontalis and Piromyces rhizinflata, were cultured on filter paper in medium containing 0, 0·45, 2·25 or 4·5 µg SAP ml−1. Filter paper digestion by both fungi was completely inhibited by 2·25 µg SAP ml−1. Steroidal saponins from Y. schidigera inhibit cellulolytic ruminal bacteria and fungi, but their effects on amylolytic bacteria are species dependent and similar to the effects of ionophores. As such, SAP may be useful in nutritional applications targeting starch-digesting ruminal micro-organisms.