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 Multicellular magnetotactic prokaryotes ( MMPs ) are a peculiar group of magnetotactic bacteria, each comprising approximately 10–100 cells of the same phylotype. Two morphotypes of MMP have been identified, including several species of globally distributed spherical mulberry‐like MMPs (s‐ MMPs ), and two species of ellipsoidal pineapple‐like MMPs (e‐ MMPs ) from C hina ( Q ingdao and R ongcheng cities). We recently collected e‐ MMPs from M editerranean S ea sediments ( S ix‐ F ours‐les‐ P lages) and D rummond I sland, in the S outh C hina S ea. Phylogenetic analysis revealed that the MMPs from S ix‐ F ours‐les‐ P lages and the previously reported e‐ MMP C andidatus   M agnetananas rongchenensis have 98.5% sequence identity and are the same species, while the MMPs from D rummond I sland appear to be a novel species, having > 7.1% sequence divergence from the most closely related e‐ MMP , C andidatus   M agnetananas tsingtaoensis. Identification of the novel species expands the distribution of e‐ MMPs to T ropical Z one. Comparison of nine physical and chemical parameters revealed that sand grain size and the content of inorganic nitrogen (nitrate, ammonium and nitrite) in the sediments from R ongcheng C ity and S ix‐ F ours‐les‐ P lages were similar, and lower than found for sediments from the other two sampling sites. The results of the study reveal broad diversity and wide distribution of e‐ MMPs .

Summary The luminous bacterial symbionts of anomalopid flashlight fishes, which appear to be obligately dependent on their hosts for growth, share several evolutionary patterns with unrelated obligate bacteria. However, only one flashlight fish symbiont species has been characterized in detail, and it is therefore not known if the bacteria from other anomalopid species are highly divergent (a pattern common to obligate symbionts). Unlike most obligate symbionts, the bacteria symbiotic with anomalopids are extracellular and spend time outside their hosts in the environment, from which they are thought to colonize new host generations. Environmental acquisition might decrease the likelihood of bacterial divergence between host species. We used phylogenetic analysis to determine the relatedness of symbionts from different anomalopid host species. The symbionts of hosts in the genus P hotoblepharon were resolved as a new species, for which we propose the name ‘ C andidatus   P hotodesmus blepharus’. Furthermore, different genera of anomalopids were found to harbour different species of bacteria, even when the hosts overlapped in geographic range. This finding suggests that the divergence between bacterial species is not the result of geographic isolation. The specificity of symbionts to host genera is consistent with obligate dependence on the host and has implications for symbiont transmission.

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.