Systematic and applied microbiology最新文献

Stable taxon names for Bacteria and Archaea are essential for capturing and documenting prokaryotic diversity. They are also crucial for scientific communication, effective accumulation of biological data related to the taxon names and for developing a comprehensive understanding of prokaryotic evolution. However, after more than a hundred years, taxonomists have succeeded in valid publication of only around 30 000 species names, based mostly on pure cultures under the International Code of Nomenclature of Prokaryotes (ICNP), out of the millions estimated to reside in the biosphere. The vast majority of prokaryotic species have not been cultured and are becoming increasingly known to us via culture-independent sequence-based approaches. Until recently, such taxa could only be addressed nomenclaturally via provisional names such as Candidatus or alphanumeric identifiers. Here, we present options and considerations to facilitate validation of names for these taxa using the recently established Code of Nomenclature of Prokaryotes Described from Sequence Data (SeqCode). Community engagement and participation of relevant taxon specialists are critical and encouraged for the success of endeavours to formally name the uncultured majority.

One hundred and sixty-three extreme halophiles were recovered from a single sample collected from an inland solar saltern in Rio Maior. Based on random amplified polymorphic DNA (RAPD) profiles and partial 16S rRNA gene sequencing 125 isolates were identified as members of the Archaea domain within the genus Halorubrum. Two strains, RMP-11^T and RMP-47, showed 99.1 % sequence similarity with the species Halorubrum californiense based on phylogenetic analysis of the 16S rRNA gene sequence. However, phylogenetic analysis based on five housekeeping genes, atpB, EF-2, glnA, ppsA and rpoB’, showed Halorubrum coriense as the closest related species with 96.7 % similarity. The average nucleotide identity (ANI) of strains RMP-11^T, RMP-47 and species Hrr. coriense were within the range of 90.0–90.5 %, supporting that strains RMP-11^T and RMP-47 represent a novel species of the genus Halorubrum. These strains formed red-pigmented colonies that were able to grow in a temperature range of 25–50 °C. Polyhydroxyalkanoate (PHA) granules were detected in both strains. The polar lipid profile was identical to the neutrophilic species of the genus Halorubrum. The Rio Maior sample from which both strains were isolated was metagenome sequenced. We identified five metagenome-assembled genomes representing novel Halorubrum species but distinct from the species represented by strains RMP-11^T and RMP-47. Based on phylogenetic, phylogenomic, comparative genomics, physiological and chemotaxonomic parameters, we describe a new species of the genus Halorubrum represented by strains RMP-11^T (=CECT 30760^T = DSM 115521^T) and RMP-47 (=CECT 30761 = DSM 115541) for which we propose the name Halorubrum miltondacostae sp. nov.

This study provides an emended description of Acinetobacter faecalis, a species previously described based on a single isolate (YIM 103518^T) from elephant feces in China. Our emended description is based on 15 novel isolates conspecific with the A. faecalis type strain, obtained from eight cattle farms in the Czech Republic. The A. faecalis strains have relatively small genomes (≈2.5−2.7 Mbp), with a GC content of 36.3−36.7 mol%. Core genome-based phylogenetic analysis showed that the 15 strains, together with the type strain of A. faecalis, form a distinct and internally coherent phylogroup within the genus. Pairwise genomic ANIb values for the 16 A. faecalis strains were 97.32−99.04 %, while ANIb values between the genomes of the 16 strains and those of the other Acinetobacter spp. were ≤ 86.2 %. Analysis of whole-cell MALDI-TOF mass spectra supported the distinctness and cohesiveness of the taxon. The A. faecalis strains could be differentiated from the other validly named Acinetobacter spp. by the absence of hemolytic activity along with their ability to grow at 37 °C and on L-aspartate, ethanol, and L-glutamate but not at 41 °C or on adipate or 2,3-butanediol. Reduced susceptibility to sulfamethoxazole, trimethoprim and/or streptomycin was shown in eight strains, along with the presence of corresponding antibiotic resistance genes. In conclusion, this study provides a comprehensive description of A. faecalis and demonstrates its occurrence in cattle feces. Though the ecological role of A. faecalis remains unknown, our results show its ability to acquire antibiotic resistance genes, likely as an adaptation to antibiotic selection pressure in livestock farms.

Arctic soil microbial communities may shift with increasing temperatures and water availability from climate change. We examined temperature and volumetric liquid water content (VWC) in the upper 80 cm of permafrost-affected soil over 2 years (2018–2019) at the Bayelva monitoring station, Ny Ålesund, Svalbard. We show VWC increases with depth, whereas in situ temperature is more stable vertically, ranging from −5°C to 5 °C seasonally. Prokaryotic metagenome-assembled genomes (MAGs) were obtained at 2–4 cm vertical resolution collected while frozen in April 2018 and at 10 cm vertical resolution collected while thawed in September 2019. The most abundant MAGs were Acidobacteriota, Actinomycetota, and Chloroflexota. Actinomycetota and Chloroflexota increase with depth, while Acidobacteriota classes Thermoanaerobaculia Gp7-AA8, Blastocatellia UBA7656, and Vicinamibacteria Vicinamibacterales are found above 6 cm, below 6 cm, and below 20 cm, respectively. All MAGs have diverse carbon-degrading genes, and Actinomycetota and Chloroflexota have autotrophic genes. Genes encoding β -glucosidase, N-acetyl-β-D-glucosaminidase, and xylosidase increase with depth, indicating a greater potential for organic matter degradation with higher VWC. Acidobacteriota dominate the top 6 cm with their classes segregating by depth, whereas Actinomycetota and Chloroflexota dominate below ∼6 cm. This suggests that Acidobacteriota classes adapt to lower VWC at the surface, while Actinomycetota and Chloroflexota persist below 6 cm with higher VWC. This indicates that VWC may be as important as temperature in microbial climate change responses in Arctic mineral soils. Here we describe MAG-based Seqcode type species in the Acidobacteriota, Onstottus arcticum, Onstottus frigus, and Gilichinskyi gelida and in the Actinobacteriota, Mayfieldus profundus.

A dual system for naming prokaryotes is currently in place based on the well-established International Code of Nomenclature of Prokaryotes (ICNP) and the newly created Code of Nomenclature of Prokaryotes Described from Sequence Data (SeqCode). Whilst recent creation of the SeqCode opened an avenue to accelerate the naming of uncultured taxa, the existence of two codes increases the risk of species being assigned multiple validly published names. In this work we present a workflow that aims to limit conflicts by firstly naming novel cultured taxa under the SeqCode, and secondly under the ICNP, enhancing the traceability of the taxa across the two codes. To exemplify this workflow, we describe four novel taxa isolated from the intestine of pigs: Intestinicryptomonas porci gen. nov., sp. nov. (strain CLA-KB-P66^T, genome accession GCA_033971905.1^TS) within a novel family, Intestinicryptomonaceae; Grylomicrobium aquisgranensis gen. nov., sp. nov. (CLA-KB-P133^T, GCA_033971865.1^TS); Absicoccus intestinalis sp. nov. (CLA-KB-P134^T, GCA_033971885.1^TS); and Mesosutterella porci sp. nov. (oilRF-744- wt-GAM-9^T, GCF_022134585.1^TS).

Several strains were isolated from subsurface soil of the Atacama Desert and were previously assigned to the Micromonospora genus. A polyphasic study was designed to determine the taxonomic affiliation of isolates 4G51^T, 4G53, and 4G57. All the strains showed chemotaxonomic properties in line with their classification in the genus Micromonospora, including meso-diaminopimelic acid in the cell wall peptidoglycan, MK-9(H₄) as major respiratory quinone, iso-C_15:0 and iso-C_16:0 as major fatty acids and diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol as major polar lipids. The 16S rRNA gene sequences of strains 4G51^T, 4G53, and 4G57 showed the highest similarity (97.9 %) with the type strain of Micromonospora costi CS1-12^T, forming an independent branch in the phylogenetic gene tree. Their independent position was confirmed with genome phylogenies, being most closely related to the type strain of Micromonospora kangleipakensis. Digital DNA-DNA hybridization and average nucleotide identity analyses between the isolates and their closest phylogenomic neighbours confirmed that they should be assigned to a new species within the genus Micromonospora for which the name Micromonospora sicca sp. nov. (4G51^T=PCM 3031^T=LMG 30756^T) is proposed.

A novel strictly anaerobic hyperthermophilic archaeon, strain 4213-co^T, was isolated from a terrestrial hot spring in the Uzon Caldera, Kamchatka (Russian Federation). Coccoid cells were present singly, in pairs, or aggregates, and occasionally were motile. The strain grew at 75–100 °C and within a pH range of 5.4–8.2 with the optimum at 92 °C and pH 6.4–6.7. Strain 4213-co^T was a chemoorganoheterotroph, growing on proteinaceous substrates and mono-, di- and polysaccharides (starch, guar gum, xanthan gum). It did not require sodium chloride for growth. The complete genome of strain 4213-co^T was 1.74 Mbp in size; its G+C content was 36.18 %. Genome analysis allowed to identify 25 genes encoding glycosidases involved in polysaccharide hydrolysis as well as genes of ADP-forming acetate-CoA ligase, lactate dehydrogenase and two [NiFe] hydrogenases responsible for acetate, lactate and hydrogen formation during fermentation. Moreover gene cluster encoding archaellum subunits was found. According to the phylogenomic analysis strain 4213-co^T formed a species-level phylogenetic lineage within Ignisphaera genus. Our phylogenomic analysis also supports the delineation of the Ignisphaera genus into a separate family Ignisphaeraceae, as recently published. Here we propose a novel species Ignisphaera cupida, sp. nov. with type strain 4213-co^T (=JCM 39446^T=VKM B-3715^T=UQM 41593^T). Ecogenomic analysis showed that representatives of the Ignisphaera are thermophilic archaea, the majority of them were found in terrestrial hot springs and deep-sea hydrothermal vents. This study allowed a better understanding of physiology and ecology of Ignisphaeraceae – a rather understudied archaeal group.

We present new genomes from the bacterial symbiont Candidatus Dactylopiibacterium carminicum obtained from non-domesticated carmine cochineals belonging to the scale insect Dactylopius (Hemiptera: Coccoidea: Dactylopiidae). As Dactylopiibacterium has not yet been cultured in the laboratory, metagenomes and metatranscriptomics have been key in revealing putative symbiont functions. Dactylopiibacterium is a nitrogen-fixing beta-proteobacterium that may be vertically transmitted and shows differential gene expression inside the cochineal depending on the tissue colonized. Here we found that all cochineal species tested had Dactylopiibacterium carminicum which has a highly conserved genome. All Dactylopiibacterium genomes analyzed had genes involved in nitrogen fixation and plant polymer degradation. Dactylopiibacterium genomes resemble those from free-living plant bacteria, some found as endophytes. Notably, we found here a new putative novel function where the bacteria may protect the insect from viruses, since all Dactylopiibacterium genomes contain CRISPRs with a spacer matching nucleopolyhedrovirus that affects insects.