Environmental Microbiology Reports

Summary Anaerobic ammonium‐oxidizing (anammox) bacteria affiliated with the genus ‘ Candidatus Scalindua’ are responsible for significant nitrogen loss in oceans, and thus their ecophysiology is of great interest. Here, we enriched a marine anammox bacterium, ‘ Ca . S. japonica’ from a Hiroshima bay sediment in Japan, and comparative genomic and proteomic analyses of ‘ Ca . S. japonica’ were conducted. Sequence of the 4.81‐Mb genome containing 4019 coding regions of genes (CDSs) composed of 47 contigs was determined. In the proteome, 1762 out of 4019 CDSs in the ‘ Ca . S. japonica’ genome were detected. Based on the genomic and proteomic data, the core anammox process and carbon fixation of ‘ Ca . S. japonica’ were further investigated. Additionally, the present study provides the first detailed insights into the genetic background responsible for iron acquisition and menaquinone biosynthesis in anammox bacterial cells. Comparative analysis of the ‘ Ca . Scalindua’ genomes revealed that the 1502 genes found in the ‘ Ca . S. japonica’ genome were not present in the ‘ Ca . S. profunda’ and ‘ Ca . S. rubra’ genomes, showing a high genomic diversity. This result may reflect a high phylogenetic diversity of the genus ‘ Ca . Scalindua’.

Summary Knowledge concerning microbial infectious diseases in the current amphibian crisis is rudimentary and largely limited to ranavirosis and chytridiomycosis. The family Chlamydiaceae is gaining attention as a common cause of disease in amphibians and may harbour new and emerging amphibian pathogens. We identified a novel species of Chlamydiales (Candidatus Amphibiichlamydia ranarum ) with a prevalence of 71% in exotic invasive bullfrog tadpoles ( Lithobates catesbeianus ) from an introduced population in the Netherlands. The sequence of a 1474 bp 16S rRNA gene fragment showed that the novel taxon forms a well‐defined clade with ‘ Candidatus Amphibiichlamydia salamandrae’ within the Chlamydiaceae family. Although none of the tadpoles examined showed signs of clinical disease, urgent evaluation of its pathogenic potential for native amphibian species is required.