Cheng, Lei

An anaerobic, thermophilic methanogen, designated strain LWZ-6T, was isolated from the Shengli oil field, China. The cells of strain LWZ-6T were non-motile cocci, with a diameter of 0.5–1.0 µm, and formed aggregates. They reduced methanol and monomethylamine into methane, using H2 as an electron donor. Dimethylamine, trimethylamine and methanethiol, H2/CO2, formate, acetate, pyruvate, lactate and glucose were not used as energy sources. Strain LWZ-6T required yeast extract, acetate or CO2 as carbon sources. Strain LWZ-6T grew at 35–65 °C (optimum 55 °C), pH 5.0–8.0 (optimum 6.0–6.5) and 0–60 g l−1 NaCl (optimum 9 g l−1). The genome was 1.54 Mbp with a G+C content of 54.42 mol%. Strain LWZ-6T shared 83.54% 16S rRNA gene sequence identity with Infirmifilum lucidum strain 3507LTT in the class Thermoprotei. Phylogenetic analysis based on the 16S rRNA gene, along with phylogenomic analysis, indicated that strain LWZ-6T belonged to the candidate class ‘Candidatus Methanomethylicia’, which lacks cultivated representatives. Based on these findings, a new species within a new genus, Methanosuratincola petrocarbonis gen. nov., sp. nov., is proposed for LWZ-6T (=CCAM 1872T=JCM 39528T). In addition, we propose the Methanosuratincolia class. nov. for candidate class ‘Ca. Methanomethylicia’ represented by Methanosuratincolaceae fam. nov. and Methanosuratincolales ord. nov. within the phylum Thermoproteota.

Abstract Background The Atribacterota are widely distributed in the subsurface biosphere. Recently, the first Atribacterota isolate was described and the number of Atribacterota genome sequences retrieved from environmental samples has increased significantly; however, their diversity, physiology, ecology, and evolution remain poorly understood. Results We report the isolation of the second member of Atribacterota, Thermatribacter velox gen. nov., sp. nov., within a new family Thermatribacteraceae fam. nov., and the short-term laboratory cultivation of a member of the JS1 lineage, Phoenicimicrobium oleiphilum HX-OS.bin.34TS, both from a terrestrial oil reservoir. Physiological and metatranscriptomics analyses showed that Thermatribacter velox B11T and Phoenicimicrobium oleiphilum HX-OS.bin.34TS ferment sugars and n-alkanes, respectively, producing H2, CO2, and acetate as common products. Comparative genomics showed that all members of the Atribacterota lack a complete Wood-Ljungdahl Pathway (WLP), but that the Reductive Glycine Pathway (RGP) is widespread, indicating that the RGP, rather than WLP, is a central hub in Atribacterota metabolism. Ancestral character state reconstructions and phylogenetic analyses showed that key genes encoding the RGP (fdhA, fhs, folD, glyA, gcvT, gcvPAB, pdhD) and other central functions were gained independently in the two classes, Atribacteria (OP9) and Phoenicimicrobiia (JS1), after which they were inherited vertically; these genes included fumarate-adding enzymes (faeA; Phoenicimicrobiia only), the CODH/ACS complex (acsABCDE), and diverse hydrogenases (NiFe group 3b, 4b and FeFe group A3, C). Finally, we present genome-resolved community metabolic models showing the central roles of Atribacteria (OP9) and Phoenicimicrobiia (JS1) in acetate- and hydrocarbon-rich environments. Conclusion Our findings expand the knowledge of the diversity, physiology, ecology, and evolution of the phylum Atribacterota. This study is a starting point for promoting more incisive studies of their syntrophic biology and may guide the rational design of strategies to cultivate them in the laboratory.

A microaerophilic, Gram-negative, motile, and spiral-shaped bacterium, designated Y-M2T, was isolated from oil sludge of Shengli oil field. The optimal growth condition of strain Y-M2T was at 25 °C, pH 7.0, and in the absence of NaCl. The major polar lipid was phosphatidylethanolamine. The main cellular fatty acid was iso-C17  :  0 3-OH. It contained Q-9 and Q-10 as the predominant quinones. The DNA G+C content was 68.1 mol%. Strain Y-M2T showed the highest 16S rRNA gene sequence similarity to Telmatospirillum siberiense 26-4bT (91.1 %). Phylogenetic analyses based on 16S rRNA gene and genomes showed that strain Y-M2T formed a distinct cluster in the order Rhodospirillales. Genomic analysis showed that Y-M2T possesses a complete nitrogen-fixation cluster which is phylogenetically close to that of methanogene. The nif cluster, encompassing the nitrogenase genes, was found in every N2-fixing strain within the order Rhodospirillales. Phylogeny, phenotype, chemotaxonomy, and genomic results demonstrated that strain Y-M2T represents a novel species of a novel genus in a novel family Oleispirillaceae fam. nov. in the order Rhodospirillales, for which the name Oleispirillum naphthae gen. nov., sp. nov. was proposed. The type strain is Y-M2T (=CCAM 827T=JCM 34765T).

Abstract Acidimicrobiia are widely distributed in nature and suggested to be autotrophic via the Calvin–Benson–Bassham (CBB) cycle. However, direct evidence of chemolithoautotrophy in Acidimicrobiia is lacking. Here, we report a chemolithoautotrophic enrichment from a saline lake, and the subsequent isolation and characterization of a chemolithoautotroph, Salinilacustristhrix flava EGI L10123T, which belongs to a new Acidimicrobiia family. Although strain EGI L10123T is autotrophic, neither its genome nor Acidimicrobiia metagenome-assembled genomes from the enrichment culture encode genes necessary for the CBB cycle. Instead, genomic, transcriptomic, enzymatic, and stable-isotope probing data hinted at the activity of the reversed oxidative TCA (roTCA) coupled with the oxidation of sulfide as the electron donor. Phylogenetic analysis and ancestral character reconstructions of Acidimicrobiia suggested that the essential CBB gene rbcL was acquired through multiple horizontal gene transfer events from diverse microbial taxa. In contrast, genes responsible for sulfide- or hydrogen-dependent roTCA carbon fixation were already present in the last common ancestor of extant Acidimicrobiia. These findings imply the possibility of roTCA carbon fixation in Acidimicrobiia and the ecological importance of Acidimicrobiia. Further research in the future is necessary to confirm whether these characteristics are truly widespread across the clade.

A novel obligately anaerobic, thermophilic and formate-utilizing bacterium K32T was isolated from Shengli oilfield of China. Cells were straight rods (0.4–0.8 µm × 2.5–8.0 µm), Gram-stain-positive, non-spore-forming and slightly motile. Optimum growth occurred with pH of 7 and 0.5 g l–1 NaCl under temperature of 55–60 °C. Nitrate could be reduced into nitrite, syntrophic formate oxidation to methane and carbon dioxide occurred when co-culturing strain K32T and Methanothermobacter thermautotrophicus ΔH. The main cellular fatty acids were iso-C15 : 0 (24.0 %), anteiso-C15 : 0 (21.7 %), C16 : 0 (12.7 %) and C14 : 0 (10.8 %), and the main polar lipid was phosphatidylglycerol. The G+C content of the genomic DNA was 46.3 mol%. The 16S rRNA gene sequence of K32T shared ≤90.4 % of sequence similarity to closest type strains of Desulfitibacter alkalitolerans , Calderihabitans maritimus and members of the genus Moorella . Based on the phenotypic, biochemical and genotypic characterization, Zhaonella formicivorans gen. nov., sp. nov. is proposed with K32T (=CCAM 584T =DSM 107278T=CGMCC1.5297T) as the type strain, which is the first representative of Zhaonellaceae fam. nov. In addition, the order Thermoanaerobacterales and family Peptococcaceae were reclassified, and three novel families in the novel order of Moorellales ord. nov. were also proposed.

A novel Gram-stain-positive, rod shaped and anaerobic bacterium, designated as W6T, was isolated from Shengli oilfield in China. Strain W6T was observed to grow from 20 to 45 °C with pH 6.5–9.0 (optimally at 40 °C and pH of 7.5) and without addition of NaCl. The major cellular fatty acids were iso-C15 : 0 (29.1%), C14 : 0 (27.0%) and C16 : 0 (12.2%), and the main polar lipids were lipids (L) and aminolipids (AL). The DNA G+C content is 42.9 mol%. Based on 16S rRNA gene sequence analysis, strain W6T showed highest similarities to Tissierella creatinini DSM 9508T (94.9%) and Soehngenia saccharolytica DSM 12858T (94.1%). The morphological, physiological, biochemical, phylogenetic and phylogenomic analyses demonstrated strain W6T (CCAM 534T=DSM 28124T=CGMCC 1.5291T) represents a novel species in a new genus, for which the name Gudongella oleilytica gen. nov. sp. nov. is proposed. The family Tissierellaceae is proposed as a new family containing the genera Anaerosalibacter , Gudongella, Keratinibaculum , Soehngenia , Sporanaerobacter , Tepidimicrobium , Tissierella , Urmitella and species Clostridium ultunense based on the phylogenetic and phylogenomic analyses.