Aerophototrophica crusticola gen. nov., sp. nov., isolated from desert biocrusts

Virgifigura deserti gen. nov., sp. nov., isolated from the Gurbantunggut Desert soil

A Gram-stain-negative, aerobic, rod-shaped bacterial strain, SYSU D60014T, was isolated from a sandy soil sample collected from the Gurbantunggut Desert in Xinjiang, PR China. Colonies of SYSU D60014T were pink-coloured, crystalline, irregular edge with a rough surface. Phylogenetic analyses based on both the 16S rRNA gene and whole-genome sequences assigned strain SYSU D60014T belonged to the family Rhodospirillaceae, formed a distinct lineage and showed 92.5-91.0% similarity to closely related strains. Digital DNA-DNA hybridization, average nucleotide identity and average amino acid identity values between strain SYSU D60014T and members of its related species were 17.2-19.6%, 70.8-74.4% and 48.9-64.5%, respectively. The complete genome of strain SYSU D60014T was 5,100,926 bp with a DNA G+C content of 65.1%. Cells were oxidase-positive and catalase-negative. The strain could grow at 28-40 °C (optimum, 37 °C), pH 5.0-8.0 (optimum, pH 7.0), and in the presence of up to 3% NaCl (optimum, 1-1.5%, w/v) on R2A. The predominant menaquinone was Q-10. The main polar lipids were phosphatidylethanolamine, phosphatidylmethyl ethanolamine, diphosphatidylglycerol, unidentified aminophospholipid, unidentified aminolipid, unidentified phospholipid, four unidentified polar lipids and two unidentified phosphoglycolipids. Major cellular fatty acids were C19 : 0 cyclo ω8c, summed feature 8 (C18 : 1  ω7c and/or C18 : 1  ω6c) and C16 : 0. Based on the results obtained through genotypic and phenotypic analyses, we propose that strain SYSU D60014T represents a novel species and genus within the family Rhodospirillaceae, for which we propose the name Virgifigura deserti gen. nov., sp. nov. (type strain SYSU D60014T=NBRC 112951T=CPCC 101030T).

Oleispirillum naphthae gen. nov., sp. nov., a bacterium isolated from oil sludge, and proposal of Oleispirillaceae fam. nov

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).

Shumkonia mesophila gen. nov., sp. nov., a novel representative of Shumkoniaceae fam. nov. and its potentials for extracellular polymeric substances formation and sulfur metabolism revealed by genomic analysis

A microaerophilic, mesophilic, chemoorganoheterotrophic bacterium, designated Y-P2T, was isolated from oil sludge enrichment in China. Cells of the strain were Gram-stain-negative, non-motile, non-spore-forming, rod-shaped or slightly curved with 0.8-3.0 µm in length and 0.4-0.6 µm in diameter. The strain Y-P2T grew optimally at 25 °C (range from 15 to 30 °C) and pH 7.0 (range from pH 6.0 to 7.5) without NaCl. The major cellular fatty acids were C16:0, summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), summed feature 8 (C18:1 ω7c and/or C18:1 ω6c). The main polar liquids of strain Y-P2T comprised phosphatidylethanolamine (PE) and phosphatidylglycerol (PG). The respiratory quinone was Q-10. Acetate and H2 were the fermentation products of glucose. The DNA G + C content was 66.0%. Strain Y-P2T shared the highest 16S rRNA gene sequence similarity (90.3-90.6%) with species within Oceanibaculum of family Thalassobaculaceae in Rhodospirillales. Phylogenetic analyses based on 16S rRNA gene sequences and genomes showed that strain Y-P2T formed a distinct evolutionary lineage within the order Rhodospirillales. On the basis of phenotypic, phylogenetic and phylogenomic data, we propose that strain Y-P2T represents a novel species in a novel genus, for which Shumkonia mesophila gen. nov., sp. nov., within a new family Shumkoniaceae fam. nov. The type strain is Y-P2T (= CCAM 826 T = JCM 34766 T).

Seasonal Dynamics of Lake Winnipeg’s Microbial Communities Reveal Aerobic Anoxygenic Phototrophic Populations Coincide with Sunlight Availability

In this first comprehensive study of Lake Winnipeg’s microbial communities, limnetic and littoral euphotic zones were examined during each season from 2016 through 2020. Classical cultivation and modern high-throughput sequencing techniques provided quantification and identification of key phototrophic populations, including aerobic anoxygenic phototrophs (AAP). Annual dynamics found total heterotrophs reached 4.23 × 10⁶ CFU/g in littoral sands, and 7.69 × 10⁴ CFU/mL in summer littoral waters on oligotrophic media, higher counts than for copiotrophic compositions. Limnetic numbers inversely dipped to 4.34 × 10³ CFU/mL midsummer. Cultured AAP did not follow heterotrophic trends, instead peaking during the spring in both littoral and limnetic waters as 19.1 and 4.7% of total copiotrophs, or 3.9 and 4.9% of oligotrophs, decreasing till autumn each year. Complementary observations came from environmental 16S V4 rRNA gene analysis, as AAP made up 1.49 and 1.02% of the littoral and limnetic sequenced communities in the spring, declining with seasonal progression. Spatial and temporal fluctuations of microbes compared to environmental factors exposed photosynthetic populations to independently and regularly fluctuate in the ecosystem. Oxygenic phototrophic numbers expectantly matched the midsummer peak of Chl a and b, oxygenic photosynthesis related carbon fixation, and water temperature. Independently, AAP particularly colonized spring littoral areas more than limnetic, and directly corresponded to habitat conditions that specifically promoted growth: the requirement of light and organic material.