The chemical composition of rumen bacteria and cell walls from rumen bacteria

Abstract

I . Rumen bacteria were prepared in bulk from freshly killed sheep. They were exposed to ultrasonic disintegration and a preparation of cell walls was made by differential centrifugation.2. The amino acid composition of acid hydrolysates of whole cells and cell walls was determined. Summation of these results shows that whole cells contained approximately 40 Yo amino acids and cell walls approximately 3 0 yo. 3.A considerable proportion of the alanine content of cell walls was present as the D-isomer, partly ester linked as in teichoic acids and partly more tightly bound in 'peptide linkage' being released only after hydrolysis in constant boiling hydrochloric acid. 4. Cell walls were found to possess an alanine racemase which was inactivated only after incubation of the cell walls in 0.1 M-NaOH. Whole cells contained approximately 8 yo carbohydrates and cell walls approximately 5 yo.The glucose and galactose contents of whole cells and cell walls were low, accounting for little more than 2 yo of the dry weight of the bacterial samples. 6.The amino sugar content of bacterial samples was approximately 3 % and consisted mainly of glucosamine. 7.The total lipid content of rumen bacteria was approximately 25 yo and that of cell walls varied considerably between 10 and 23 Yo.

The Microbial Contribution to Human Faecal Mass

“…Microscopy suggested that they were simply smaller particles of fibrous debris that had passed through the nylon mesh. In ruminant work, such particles are removed by centrifuging at low speed, for example 200 g (Hoogenraad and Hird, 1970), but we found that this procedure also precipitated significant amounts of microbial matter. The particles were therefore removed from the fluid by leaving them to sediment for 5 min.…”

“…The composition of rumen microflora has been studied by isolating bacteria by filtering and centrifugation (Hoogenraad and Hird, 1970;Smith and McAllan, 1974). This approach was also applied early in this century to the quantitation of the bacteria in human faeces and gave values of around 30% for the bacterial component of faecal solids, (MacNeal, Latzer and Kerr, 1909).…”

“…We have therefore developed a method that fractionates faeces into three main components: the bacteria, undigested fibre, and soluble substances. The procedure has been developed from techniques used to isolate microbial matter from the rumen (Hoogenraad and Hird, 1970;Smith and McAllan 1974), with several steps altered or omitted to improve the separation of bacteria from fibrous debris and to ensure the purity of the bacterial fraction. By this method, a direct estimate of the microbial contribution to the weight of the stool has been obtained.…”

Studies on rumen metabolism. IX. Contribution of plant lipases to the release of free fatty acids in the rumen

“…Fd Agric. 1974, 25,439 In this paper the role of plant lipases in the lipolysis of ingested lipids has been investigated. Maceration or homogenisation of leaf tissue releases a number of enzymes which rapidly degrade and transform the principal lipid constituents in leaves.…”

Evaluation of the Two-Stage Technique for the in Vitro Estimation of the Dry Matter Digestibility of Corn Silage

“…Based on the composition of rumen bacteria (Hoogenraad and Hird 1970) and the digestibility of bacterial protein in pepsin (Bergen et al 1968) (1966) and Goering and Van Soest (1970 (1966) …”