Papillibacter cinnamivorans gen. nov., sp. nov., a cinnamate-transforming bacterium from a shea cake digester

A new, strictly anaerobic, Gram-positive, non-sporulating, mesophilic bacterium, designated strain CIN1T (T=type strain) was isolated from an anaerobic digester fed with shea cake rich in tannins and aromatic compounds. Cells of strain CIN1T were rod-shaped, had characteristically pointed ends (1.3-3.0 x 0.5-0.6 microns) and occurred singly, in pairs and sometimes in chains of up to six. The pH range for growth was 6.9-8.5 and the temperature growth range was 15-40°C. Optimum growth occurred with yeast extract and cinnamate at 37°C and a pH of 7.5. The isolate transformed cinnamate by degrading the aliphatic side chain to produce acetate and benzoate rather than by aromatic ring cleavage or demethoxylation. The position of the methoxyl group appears to be important in the degradation of the aliphatic side chain of cinnamate ; consequently, 3-methoxycinnamate and 4-mathoxycinnamate, but not 2-methoxycinnamate, are transformed to produce acetate and methoxybenzoates, namely 3-methoxybenzoate and 4-methoxybenzoate respectively. Crotonate is degraded to acetate and butyrate. The G+C content of the DNA is 56 mol%. Phylogenetic analysis of the 16S rRNA gene of strain CIN1T indicated that it was a menber of the low-G+C-containing Gram-positive branch with a specific relation ship to #Sporobacter termitidis$(sequence identity of 88$ gen. nov., sp. nov. (Résumé d'auteur

Novel microbial diversity adherent to plant biomass in the herbivore gastrointestinal tract, as revealed by ribosomal intergenic spacer analysis and rrs gene sequencing

It is well recognized that a dynamic biofilm develops upon plant biomass in the herbivore gastrointestinal tract, but this component of the microbiome has not previously been specifically sampled, or directly compared with the biodiversity present in the planktonic fraction of digesta. In this study, the digesta collected from four sheep fed two different diets was separated into three fractions: the planktonic phase, and the microbial populations either weakly or tightly adherent to plant biomass. The community DNA prepared from each fraction was then subjected to both ribosomal intergenic spacer analysis (RISA) and denaturing gradient gel electrophoresis (DGGE). Both types of analysis showed that dietary factors influence community structure, and that the adherent fractions produced more complex profiles. The RIS-clone libraries prepared from the planktonic and adherent populations were then subjected to restriction fragment length polymorphism (RFLP) and DNA sequence analyses, which resulted in a far greater degree of discrimination among the fractions. Although many of the sequenced clones from the adherent populations were assigned to various clusters within the low G+C Gram-positive bacteria, the clone libraries from animals consuming an all-grass diet were largely comprised of novel lineages of Clostridium, while in animals consuming the starch-containing diet, Selenomonas and Ruminococcus spp. were the dominant low G+C Gram-positive bacteria. Additionally, the libraries from hay-fed animals also contained clones most similar to asaccharolytic Clostridia, and other Gram-positive bacteria that specialize in the transformation of plant phenolic compounds and the formation of cinnamic, phenylacetic and phenylpropionic acids. These results reveal, for the first time, the phylogeny of adherent subpopulations that specialize in the transformation of plant lignins and other secondary compounds, which potentiate polysaccharide hydrolysis by other members of the biofilm