Fiber-Degrading Systems of Different Strains of the Genus Fibrobacter

Abstract

The S85 type strain of Fibrobacter succinogenes, a major ruminal fibrolytic species, was isolated 49 years ago from a bovine rumen and has been used since then as a model for extensive studies. To assess the validity of this model, we compared the cellulase-and xylanase-degrading activities of several other F. succinogenes strains originating from different ruminants, including recently isolated strains, and looked for the presence of 10 glycoside hydrolase genes previously identified in S85. The NR9 F. intestinalis type strain, representative of the second species of the genus, was also included in this study. DNA-DNA hybridization and 16S rRNA gene sequencing first classified the strains and provided the phylogenetic positions of isolates of both species. Cellulase and xylanase activity analyses revealed similar activity profiles for all F. succinogenes strains. However, the F E strain, phylogenetically close to S85, presented a poor xylanolytic system and weak specific activities. Furthermore, the HM2 strain, genetically distant from the other F. succinogenes isolates, displayed a larger cellulolytic profile on zymograms and higher cellulolytic specific activity. F. intestinalis NR9 presented a higher cellulolytic specific activity and a stronger extracellular xylanolytic activity. Almost all glycoside hydrolase genes studied were found in the F. succinogenes isolates by PCR, except in the HM2 strain, and few of them were detected in F. intestinalis NR9. As expected, the fibrolytic genes of strains of the genus Fibrobacter as well as the cellulase and xylanase activities are better conserved in closely related phylogenetic isolates.

Bacterial community diversity in paper mills processing recycled paper

“…Lahtinen et al [24] also recovered sequences of organisms in the TM7 phylum, suggesting this as yet uncultured group may be common in several types of paper mills. Also present in our paper mill were the clones SSW131 and SSW122 with close sequence homology to Fibrobacter intestinales, which is the only genus in the whole phylum of Fibrobacteres [2]. The two species of cellulolytic Fibrobacter isolated thus far were from animals [2].…”

Identification and Characterization of a Cellulase-Encoding Gene from the Buffalo Rumen Metagenomic Library

“…F. succinogenes has been reported to be a major fiber-digesting rumenial bacterium in the gastrointestinal tracts of herbivorous animals, especially when the animals are fed a poor diet. 41,42) F. succinogenes can effectively degrade lignocelluloses and shows strong ability to solubilize xylan. 42) In addition to the identified ORFs with homology to cellulolytic and xylanolytic enzymes, other putative ORFs with recognizable identity to a wide variety of other proteins were also discovered by sequence analysis.…”

Cellulosilyticum ruminicola , a Newly Described Rumen Bacterium That Possesses Redundant Fibrolytic-Protein-Encoding Genes and Degrades Lignocellulose with Multiple Carbohydrate- Borne Fibrolytic Enzymes

“…The (hemi)cellulolytic enzyme systems have been intensively studied for nonrumen anaerobic bacteria, including Clostridium thermocellum (19,40), Clostridium cellulolyticum (6), Clostridium cellulovorans (13), and Clostridium stercorarium (47), as well as the rumen species, Rumicoccocus albus (35), Ruminococcus flavefaciens (32), and Fibrobacter succinogenes (4). The results indicate that most of them, except for Fibrobacter succinogenes, produce multiple cellulolytic enzymes integrated in a complex, cellulosome, and free individual proteins.…”