THE USE OF 16S RIBOSOMAL-RNA-TARGETED OLIGONUCLEOTIDE PROBES TO STUDYCOMPETITION BETWEEN RUMINAL FIBROLYTIC BACTERIA - PURE-CULTURE STUDIES WITH CELLULOSE AND ALKALINE PEROXIDE-TREATED WHEAT-STRAW

Specific oligonucleotide probes targeted,to sites on the 16S rRNA of R uminococcus albus 8, Ruminococcus flavefaciens FD-1, and Fibrobacter s uccinogenes S85 and a domain Bacteria probe were used to study bacteri al interactions during the fermentation of cellulose and alkaline hydr ogen peroxide-treated wheat straw in monocultures, dicultures, and tri cultures. Results showed that R. albus 8 inhibited the growth of R. fl avefaciens FD-1 when grown as a diculture with cellulose or alkaline h ydrogen peroxide-treated wheat straw as the carbon source. In dicultur es containing R. albus 8 and F. succinogenes S85 groan on cellulose or alkaline hydrogen peroxide-treated wheat straw, competition was not d etected. R. flavefaciens FD-1 outcompeted F. succinogenes S85 when cel lulose was used as the carbon source. In tricultures with cellulose as the carbon source, R. flavefaciens FD-1 was inhibited, R. albus 8 app eared to dominate during the early phase of degradation (12 to 48 h), while F. succinogenes S85 became predominant during the later phase of degradation (60 to 70 h). When alkaline hydrogen peroxide-treated whe at straw was used as a growth substrate, F. succinogenes S85 showed be tter growth than either R. albus 8 or R. flavefaciens FD-1. However, R . flavefaciens FD-1 was present in small numbers throughout the incuba tion period, unlike the growth patterns when cellulose was the carbon source.