COMPARISON OF UTILIZATION OF PECTINS FROM VARIOUS SOURCES BY PURE CULTURES OF PECTINOLYTIC RUMEN BACTERIA AND MIXED CULTURES OF RUMEN MICROORGANISMS

Utilization of citrus, lucerne, apple and sugar beet pulp pectins by p ure strains of rumen bacteria, Prevotella ruminicola, Lachnospira mult iparus and Butyrivibrio fibrisolvens was compared. Additionally, the u tilization of pectins by mixed rumen microorganisms was evaluated. The comparison was based on the depletion of galacturonic acid from mediu m, content of cellular protein in the cultures and the amount of end p roducts of pectin fermentation in cell-free culture fluids. It was fou nd that citrus pectin was utilized best; utilization of lucerne, apple and sugar beet pectins was dependent on the species of bacteria. P. r uminicola and B. fibrisolvens utilized polygalacturonic acid from suga r 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 pu re cultures of rumen bacteria. The amount of fermentation products in the culture fluids supported the conclusion that citrus pectin was uti lized better than others. Microbial protein content in the cultures wa s found to be a less sensitive indicator of pectin utilization than th e remaining examined parameters. P. ruminicola strains and mixed cultu res of rumen microorganisms were shown to have the highest ability to utilize pectins, L. multiparus - moderate, while the B. fibrisolvens s train utilized pectin the least.