A new, strictly anaerobic, Gram-positive, non-sporulating, mesophilic bacterium, designated strain CIN1(T) (T=type strain) was isolated from an anaerobic digester fed with shea cake rich in tannins and aromatic compounds. Cells of strain CIN1(T) were rod-shaped, had characteristically pointed ends (1.3--3.0 x 0.5--0.6 microm) 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 degrees C. Optimum growth occurred with yeast extract and cinnamate at 37 degrees 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-methoxycinnamate, 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 CIN1(T) indicated that it was a member of the low-G+C-containing Gram-positive branch with a specific relationship to Sporobacter termitidis (sequence identity of 88%). The phylogenetic results concur with the phenotypic data which reveals that the isolate is a novel bacterium and, based on these findings, strain CIN1(T) (=DSM 12816(T)=ATCC 700879(T)) has been designated Papillibacter cinnamivorans gen. nov., sp. nov.