Tamaki, Hideyuki

A Gram-negative, obligatory anaerobic, chemoheterotrophic bacterium, designated strain IA91T, was isolated from sediments and formation water from deep aquifers in Japan. IA91T derives its peptidoglycan, energy and carbon from exogenous cell wall fragments, namely muropeptides, released from actively reproducing bacteria, and is dependent on other bacteria for cell wall formation, growth and even cell shape: IA91T is irregular rod-shaped but coccoids when muropeptide is absent. IA91T grew in a temperature range of 25–45 °C with optimum growth at 40 °C. IA91T utilized limited substrates, yeast extract, muropeptides and d-lactate. The major end products from yeast extract degradation were acetate, hydrogen and carbon dioxide. Co-cultivation with a hydrogen-scavenging methanogenic archaeon promoted IA91T growth. No anaerobic respiration with nitrate, nitrite, sulphate or Fe(III) was observed. The major cellular fatty acids are C16 : 0, C18 : 1 trans9, C18 : 0 and C17 : 0. The G+C content of the genomic DNA was 45.6 mol%. Phylogenetic analysis based on 16S rRNA gene and conserved protein sequences involved in replication, transcription and translation indicated that IA91T belonged to the candidate phylum Marine Group A (MG-A, SAR406 or Ca. Marinimicrobia) with no cultivated representatives. Based on the phenotypic and phylogenomic characteristics, a new genus and species, Fidelibacter multiformis gen. nov., sp. nov., is proposed for IA91T (= JCM 39387T = KCTC 25736T). In addition, a new bacterial phylum named Fidelibacterota phyl. nov. is proposed for the candidate phylum MG-A represented by F. multiformis and Fidelibacteraceae fam. nov., Fidelibacterales ord. nov. and Fidelibacteria classis nov.

Our previous studies indicate the abundant and diverse presence of yet-to-be-cultured microorganisms in the micropore-filtered fractions of various environmental samples. Here, we isolated a novel bacterium (designated as strain TMPK1T) from a 0.45-μm-filtered soil suspension by using a gel-filled microwell array device comprising 900 microwells and characterized its phylogenetic and physiological features. This strain showed low 16S rRNA gene sequence identities (<91%) and low average nucleotide identity values (<70%) to the closest validly described species, and belonged to a novel-family-level lineage within the orderRhodospirillalesofAlphaproteobacteria. Strain TMPK1Texhibited small cell sizes (0.08–0.23 μm3) and had a high cyclopropane fatty acid content (>13%), and these characteristics were differentiated from otherRhodospirillalesbacteria. A comprehensive habitability search using amplicon datasets suggested that TMPK1Tand its close relatives are mainly distributed in soil and plant-associated environments. Based on these results, we propose that strain TMPK1Trepresents a novel genus and species namedRoseiterribacter gracilisgen. nov., sp. nov. (JCM 34627T= KCTC 82790T). We also proposeRoseiterribacteraceaefam. nov. to accommodate the genusRoseiterribacter.

AbstractA key feature that differentiates prokaryotic cells from eukaryotes is the absence of an intracellular membrane surrounding the chromosomal DNA. Here, we isolate a member of the ubiquitous, yet-to-be-cultivated phylum ‘Candidatus Atribacteria’ (also known as OP9) that has an intracytoplasmic membrane apparently surrounding the nucleoid. The isolate, RT761, is a subsurface-derived anaerobic bacterium that appears to have three lipid membrane-like layers, as shown by cryo-electron tomography. Our observations are consistent with a classical gram-negative structure with an additional intracytoplasmic membrane. However, further studies are needed to provide conclusive evidence for this unique intracellular structure. The RT761 genome encodes proteins with features that might be related to the complex cellular structure, including: N-terminal extensions in proteins involved in important processes (such as cell-division protein FtsZ); one of the highest percentages of transmembrane proteins among gram-negative bacteria; and predicted Sec-secreted proteins with unique signal peptides. Physiologically, RT761 primarily produces hydrogen for electron disposal during sugar degradation, and co-cultivation with a hydrogen-scavenging methanogen improves growth. We propose RT761 as a new species, Atribacter laminatus gen. nov. sp. nov. and a new phylum, Atribacterota phy. nov.

A novel slow-growing, facultatively anaerobic, filamentous bacterium, strain MO-CFX2T, was isolated from a methanogenic microbial community in a continuous-flow bioreactor that was established from subseafloor sediment collected off the Shimokita Peninsula of Japan. Cells were multicellular filamentous, non-motile and Gram-stain-negative. The filaments were generally more than 20 µm (up to approximately 200 µm) long and 0.5–0.6 µm wide. Cells possessed pili-like structures on the cell surface and a multilayer structure in the cytoplasm. Growth of the strain was observed at 20–37 °C (optimum, 30 °C), pH 5.5–8.0 (pH 6.5–7.0), and 0–30 g l−1 NaCl (5 g l−1 NaCl). Under optimum growth conditions, doubling time and maximum cell density were estimated to be approximately 19 days and ~105 cells ml−1, respectively. Strain MO-CFX2T grew chemoorganotrophically on a limited range of organic substrates in anaerobic conditions. The major cellular fatty acids were saturated C16 : 0 (47.9 %) and C18 : 0 (36.9 %), and unsaturated C18 : 1ω9c (6.0 %) and C16 : 1ω7 (5.1 %). The G+C content of genomic DNA was 63.2 mol%. 16S rRNA gene-based phylogenetic analysis showed that strain MO-CFX2T shares a notably low sequence identity with its closest relatives, which were Thermanaerothrix daxensis GNS-1T and Thermomarinilinea lacunifontana SW7T (both 85.8 % sequence identity). Based on these phenotypic and genomic properties, we propose the name Aggregatilinea lenta gen. nov., sp. nov. for strain MO-CFX2T (=KCTC 15625T, =JCM 32065T). In addition, we also propose the associated family and order as Aggregatilineaceae fam. nov. and Aggregatilineales ord. nov., respectively.

AbstractHere we employed quantitative real-time PCR (qPCR) assays for polyphosphate kinase 1 (ppk1) and 16S rRNA genes to assess relative abundances of dominant clades of Candidatus Accumulibacter phosphatis (referred to Accumulibacter) in 18 globally distributed full-scale wastewater treatment plants (WWTPs) from six countries. Accumulibacter were not only detected in the 6 WWTPs performing biological phosphorus removal, but also inhabited in the other 11 WWTPs employing conventional activated sludge (AS) with abundances ranging from 0.02% to 7.0%. Among the AS samples, clades IIC and IID were found to be dominant among the five Accumulibacter clades. The relative abundance of each clade in the Accumulibacter lineage significantly correlated (p < 0.05) with the influent total phosphorus and chemical oxygen demand instead of geographical factors (e.g. latitude), which showed that the local wastewater characteristics and WWTPs configurations could be more significant to determine the proliferation of Accumulibacter clades in full-scale WWTPs rather than the geographical location. Moreover, two novel Accumulibacter clades (IIH and II-I) which had not been previously detected were discovered in two enhanced biological phosphorus removal (EBPR) WWTPs. The results deepened our understanding of the Accumulibacter diversity in environmental samples.

Summary In an acetate‐fed anaerobic–aerobic membrane bioreactor with deteriorated enhanced biological phosphorus removal ( EBPR ), D efluviicoccus ‐related tetrad‐forming organisms ( DTFO ) were observed to predominate in the microbial community. Using metagenomics, a partial genome of the predominant DTFO , ‘ C andidatus   D efluviicoccus tetraformis strain TFO 71’, was successfully constructed and characterized. Examining the genome confirmed the presence of genes related to the synthesis and degradation of glycogen and polyhydroxyalkanoate ( PHA ), which function as energy and carbon storage compounds. TFO 71 and ‘ C andidatus   A ccumulibacter phosphatis’ ( CAP ) UW ‐1 and CAP UW ‐2, representative polyphosphate‐accumulating organisms ( PAO ), have PHA metabolism‐related genes with high homology, but TFO 71 has unique genes for PHA synthesis, gene regulation and granule management. We further discovered genes encoding DTFO polyphosphate ( polyP ) synthesis, suggesting that TFO 71 may synthesize polyP under untested conditions. However, TFO 71 may not activate these genes under EBPR conditions because the retrieved genome does not contain all inorganic phosphate transporters that are characteristic of PAOs ( CAP UW ‐1, CAP UW ‐2, M icrolunatus phosphovorus   NM ‐1 and T etrasphaera species). As a first step in characterizing EBPR ‐associated DTFO metabolism, this study identifies important differences between DTFO and PAO that may contribute to EBPR community competition and deterioration.