TAXON-SPECIFIC PROBES FOR THE CELLULOLYTIC GENUS FIBROBACTER REVEAL ABUNDANT AND NOVEL EQUINE-ASSOCIATED POPULATIONS

A total of six 16S rRNA targeted oligonucleotide probes were used to q uantify Fibrobacter abundance and diversity in the gastrointestinal co ntents of a pony. Approximately 12% of the total 16S rRNA extracted fr om cecal contents hybridized with a Fibrobacter genus-specific probe a nd a Fibrobacter succinogenes species-specific probe. However, no sign ificant hybridization was observed with a probe for the species Fibrob acter intestinalis or with three probes for F. succinogenes subspecies . This suggested the presence of a previously undescribed population o f F. succinogenes-like organisms. Novel lineages of F. succinogenes we re subsequently identified by using PCR primers specific for the genus to amplify sequences coding for 16S rRNA from DNA extracted from ceca l contents. Sequences of the cloned amplification products were shown to be affiliated with F. succinogenes but represented two distinct, an d novel, lines of descent within the species.