Publications

4859

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 .

AbstractAmmonia-oxidizing archaea (AOA) are recently found to participate in the ammonia removal processes in wastewater treatment plants (WWTPs), similar to their bacterial counterparts. However, due to lack of cultivated AOA strains from WWTPs, their functions and contributions in these systems remain unclear. Here we report a novel AOA strain SAT1 enriched from activated sludge, with its physiological and genomic characteristics investigated. The maximal 16S rRNA gene similarity between SAT1 and other reported AOA strain is 96% (with “Ca. Nitrosotenuis chungbukensis”), and it is affiliated with Wastewater Cluster B (WWC-B) based on amoA gene phylogeny, a cluster within group I.1a and specific for activated sludge. Our strain is autotrophic, mesophilic (25 °C–33 °C) and neutrophilic (pH 5.0–7.0). Its genome size is 1.62 Mb, with a large fragment inversion (accounted for 68% genomic size) inside. The strain could not utilize urea due to truncation of the urea transporter gene. The lack of the pathways to synthesize usual compatible solutes makes it intolerant to high salinity (>0.03%), but could adapt to low salinity (0.005%) environments. This adaptation, together with possibly enhanced cell-biofilm attachment ability, makes it suitable for WWTPs environment. We propose the name “Candidatus Nitrosotenuis cloacae” for the strain SAT1.

Abstract“Candidatus Achromatium palustre” was recently described as the first marine representative of the Achromatium spp. in the Thiotrichaceae - a sister lineage to the Chromatiaceae in the Gammaproteobacteria. Achromatium spp. belong to the group of large sulfur bacteria as they can grow to nearly 100 μm in size and store elemental sulfur (S0) intracellularly. As a unique feature, Achromatium spp. can accumulate colloidal calcite (CaCO3) inclusions in great amounts. Currently, both process and function of calcite accumulation in bacteria is unknown, and all Achromatium spp. are uncultured. Recently, three single-cell draft genomes of Achromatium spp. from a brackish mineral spring were published, and here we present the first draft genome of a single “Candidatus Achromatium palustre” cell collected in the sediments of the Sippewissett Salt Marsh, Cape Cod, MA. Our draft dataset consists of 3.6 Mbp, has a G + C content of 38.1 % and is nearly complete (83 %). The next closest relative to the Achromatium spp. genomes is Thiorhodovibrio sp. 907 of the family Chromatiaceae, containing phototrophic sulfide-oxidizing bacteria.