International Journal of Systematic and Evolutionary Microbiology (IJSEM), formerly International Journal of Systematic Bacteriology (IJSB), is the official journal of record for new bacterial taxa. Now in its 51st year (before 1966 it was known as the International Bulletin of Bacteriological Nomenclature and Taxonomy), the journal is the cornerstone of the ever-expanding field of microbial systematics. IJSEM publishes papers dealing with all phases of the systematics of bacteria, yeasts and yeast-like organisms, including taxonomy, nomenclature, identification, phylogeny, evolution, biodiversity, characterization and culture preservation. Its scope covers phylogenetic and evolutionary aspects of all micro-organisms, including the protists such as protozoa and algae, and will now also publish molecular environmental papers with a strong systematics content. Its international Editorial Board ensures the highest standards of peer review.