A high-throughput screening effort, designed to isolate bacteriocin-producing lactic acid bacteria (LAB) from malted cereals, resulted in the isolation of four bacteriocin-producing strains that could not be assigned conclusively to recognized species. The four isolates (UCC128(T), UCC125, UCC126 and UCC127) were found to share identical (100 %) 16S rRNA gene sequences and were therefore deemed to belong to the same species. The strains were Gram-positive, catalase-negative, non-motile homofermentative LAB. The closest recognized relative to strain UCC128(T) identified based on comparative 16S rRNA gene sequence analysis was Lactobacillus mali DSM 20444(T) (97% similarity). The strains were characterized phenotypically to identify specific growth requirements. DNA-DNA hybridization between strain UCC128(T) and L. mali DSM 20444(T) revealed a level of relatedness of only 39.4%. This indicates that strain UCC128(T) does not belong to the species L. mali. The four bacteriocin-producing strains are therefore considered to represent a novel species of the genus Lactobacillus, for which the name Lactobaciflus hordei sp. nov. is proposed. The type strain is UCC128(T) (=DSM 19519(T) =LMG 24241(T)).