Comparison of utilization of pectins from various sources by pure cultures of pectinolytic rumen bacteria and mixed cultures of rumen microorganisms.

ABSTRACT

Utilization of citrus, lucerne, apple and sugar beet pulp pectins by pure strains of rumen bacteria, Prevotella ruminicola, Lachnospira multiparus and Butyrivibrio fibrisolvens was compared. Additionally, the utilization of pectins by mixed rumen microorganisms was evaluated. The comparison was based on the depletion of galacturonic acid from medium, content of cellular protein in the cultures and the amount of end products of pectin fermentation in cell-free culture fluids. It was found that citrus pectin was utilized best; utilization of lucerne, apple and sugar beet pectins was dependent on the species of bacteria. P. ruminicola and B. fibrisolvens utilized polygalacturonic acid from sugar beet pectins better than that from apple or lucerne pectin, while L. multiparus was capable of significantly better utilization of lucerne pectin than pectin from sugar beet or apple. The source of pectin was less important for mixed cultures of rumen microorganisms than for pure cultures of rumen bacteria. The amount of fermentation products in the culture fluids supported the conclusion that citrus pectin was utilized better than others. Microbial protein content in the cultures was found to be a less sensitive indicator of pectin utilization than the remaining examined parameters. P. ruminicola strains and mixed cultures of rumen microorganisms were shown to have the highest ability to utilize pectins, L. multiparus-moderate, while the B. fibrisolvens strains utilized pectin the least.