
%0 Journal Article
%A Urdaneta, A. Barrios 
%A Fondevila, M. 
%A Balcells, J. 
%A Dapoza, C. 
%A Castrillo, C. 
%T <emph type="2">In vitro</emph> microbial digestion of straw cell wall polysaccharides in response to supplementation with different sources of carbohydrates
%J Australian Journal of Agricultural Research
%D 2000/03/01
%V 51
%N 3
%P 393-400
%K rumen bacteria, carbohydrate supplements, adhesion, enzymatic activity.
%R https://doi.org/10.1071/AR99079
%U https://www.publish.csiro.au/paper/AR99079 
%X The effect of carbohydrate supplementation on microbial fibre digestion was studied in vitro, by measuring the disappearance of cell wall monosaccharides, bacterial adhesion (mmol purine bases per g residue), and total (per g residue) and bacterial (per mmol purine bases) polysaccharidase activity. Straw cell walls (CW, 0.5% w/v) were cultured in medium supplemented with (0.275% w/v) or without starch, a sugar mixture, or pectin. Supplementation with these constituents did not cause a drop in pH below 6.1, and increased all parameters investigated with the exception of bacterial polysaccharidase activity, which was higher for CW cultures, suggesting a higher proportion of fibrolytic bacteria in the adherent population. By comparison with starch and sugar, pectin supplementation resulted in a lower proportion of residual sugars remaining from cell walls after 60 and 72 h (P &#60; 0.05), which resulted in greater bacterial adhesion after 8 and 12 h (P &#60; 0.05) and higher total cellulase activity after 8 h (P &#60; 0.01). This was perhaps because pectin may cover particle surfaces, protecting the digestive area from external factors, or may act as a substrate for cellulolytic bacteria. The lack of differences in bacterial enzymatic activities suggests the absence of qualitative or quantitative differences in the adherent fibrolytic population. 
