Description of a Novel Species Quadrisphaera endophytica sp. nov., a Potential Strain as a Plant Growth Promotor and Comparative Genome Analysis of the Genus Quadrisphaera

Rhodococcus dendrobeaniae sp. nov., an actinomycete isolated from an Arctic marine invertebrate exhibiting cytotoxic activity, and an emended description of Rhodococcus sovatensis.

A polyphasic study was conducted to establish the taxonomic status of strain T060T, an orange, aerobic, coccoid and non-motile actinomycete, isolated from a marine bryozoan (Dendrobeania sp.) collected in the Barents Sea. Phylogenetic analysis of the 16S rRNA gene sequences revealed Rhodococcus sovatensis DSM 102881T as the closest related species to strain T060T with a similarity of 99.54%. Phylogenomic analysis confirmed a close relationship between T060T and R. sovatensis DSM 102881T, while supporting their distinction. Digital DNA-DNA hybridization and average nucleotide identity values between strain T060T and R. sovatensis DSM 102881T were 26.4 and 84.3%, respectively, supporting the delineation of the isolate as a new species. Genomic characterization of the assembled genomes of T060T and R. sovatensis DSM 102881T showed genome sizes of 5.3 and 4.2 Mbp, with a G + C content of 64.38 and 65.01%, respectively. Genome analysis of strain T060T identified 15 biosynthetic gene clusters (BGCs) with low sequence similarity to known BGCs, indicating its capacity to produce unknown, potentially bioactive secondary metabolites. Furthermore, growth of T060T in eight different media revealed condition-dependent cytotoxic activity. The strongest cytotoxicity was observed for fractionated extracts from T060T grown in half-strength ISP 2 with filtered seawater against the human malignant cell lines MCF7 and A2058, and to a lesser extent against the non-malignant MRC5 cell line, highlighting its biotechnological potential. Based on the data from polyphasic taxonomy studies, it is proposed that strain T060T be classified in the genus Rhodococcus as Rhodococcus dendrobeaniae sp. nov. Additionally, the acquired data of R. sovatensis were used to amend its original description.

Terrisphaera alpina gen. nov., sp. nov., a Cellulolytic Planctomycete Representing the First Described Soil-Inhabiting Member of the Class Phycisphaerae

A novel planctomycete, strain T20PH1T, was isolated from alpine meadow soil collected at an altitude of 1800 m in the North Caucasus Mountains, Russia. Phylogenomic analysis placed it within the family Tepidisphaeraceae of the class Phycisphaerae. The closest relatives based on 16S rRNA gene sequence similarity are Fontivita pretiosa B-254T (88.9%), ‘Humisphaera borealis’ M1803T (88.6%), and Tepidisphaera mucosa 2842T (88.4%). Strain T20PH1T is the first soil-derived representative of the class Phycisphaerae. Cells of strain T20PH1T are motile, pink-pigmented cocci reproducing by binary fission. This planctomycete is an obligately aerobic chemoorganotroph with growth optima at 25–30 °C and pH 6.0–7.0. A notable functional trait of strain T20PH1T is its ability to grow on cellulose, including microcrystalline, fibrous and carboxymethyl cellulose, as well as on xylan, starch, lichenan and xanthan. The genome comprised a 5.15 Mb chromosome and a 125 kb plasmid with G + C contents of 65.97 and 66.75%, respectively. Genome analysis identified a GH5_5 subfamily cellulase as the most likely enzyme responsible for cellulose degradation by this planctomycete. Based on phenotypic and phylogenomic evidence, strain T20PH1T (=LMG 34157T = KCTC 102499T) was classified as representing a novel genus and species, Terrisphaera alpina gen. nov., sp. nov.

Pseudoneobacillus rhizolycopersici sp. nov., a novel multifunctional rhizobacterium for the biocontrol of tomato bacterial wilt.

It is confirmed that strain C159T is a novel multifunctional rhizobacterium for the biocontrol of tomato bacterial wilt and represents a novel species in the genus Pseudoneobacillus sp.

Actinomycetospora lichenicola sp. nov., a rare actinomycete isolated from the crustose lichen Arthonia leioplacella.

Komagataeibacter ossonobensis sp. nov., a novel bacterial cellulose producer isolated from an artisanal Mediterranean acetification.

Bacterial strain CS8T, a novel bacterial cellulose producer, was isolated from a 'mother of vinegar' during an artisanal acetification process in Faro, Portugal and characterized. Strain CS8T stained Gram-negative and formed rod-shaped cells that grew optimally at 30 °C and at pH 5.5-6.5. Phylogenetic analyses based on the 16S rRNA gene placed strain CS8T within the genus Komagataeibacter in a distinct lineage, showing the highest sequence similarity to Komagataeibacter diospyri (99.86%), Komagataeibacter piraceti (99.80%), Komagataeibacter europaeus (99.80%), Komagataeibacter sucrofermentans (99.79%) and Komagataeibacter nataicola (99.72%). Genomic analysis revealed that overall genome relatedness index values of CS8ᵀ with K. europaeus LMG 18890ᵀ, Komagataeibacter swingsii LMG 22125ᵀ and K. diospyri MSKU 9T were 93.7% average nucleotide identity (ANI) and 53.3% digital DNA-DNA hybridization (dDDH), 91.7% ANI and 44.7% dDDH and 90.4 and 40.4%, respectively, which are below the species delineation thresholds. The genomic DNA G+C content of CS8ᵀ is 60.7 mol%. The draft genome sequence of strain CS8T comprises 4,020,094 bases with a 225-fold mapped genome coverage. The assembled genome consists of 131 large contigs with more than 500 bp and the genome encodes 4,229 putative coding sequences. Phylogenomic analysis based on 823 core genes placed strain CS8ᵀ in a distinct clade within the genus Komagataeibacter, clustering closely with Komagataeibacter europaeus LMG 18890ᵀ. Analysis of the CS8T genome revealed the presence of the terpene, hserlactone, triceptide and methanobactin biosynthetic gene clusters. The strain harbours a complete bcs gene operon and efficiently produces bacterial cellulose from glucose. The phylogenomic, phylogenetic, phenotypic and chemotaxonomic data showed that the strain CS8T (=UCCCB 286T=CECT 31419T) represents the type of a novel species, for which we propose the name Komagataeibacter ossonobensis sp. nov.

Altererythrobacter chaiwopuensis sp. nov., a novel alphaproteobacterial strain isolated from sediment of the Chaiwopu Lake

Abstract Two alphaproteobacterial strains, designated EGI L300112T and EGI L300120, were isolated from sediment collected from Chaiwopu Lake in Xinjiang, China. The taxonomic position of the two strains was determined using polyphasic taxonomic analysis and phylogenomic analysis. Based on 16S rRNA gene sequence similarities, strain EGI L300112T and EGI L300120 were both closely related to Pelagerythrobacter rhizovicinus AY-3RT and shared the highest sequence identities of 96.2% and 96.3%, respectively. However, phylogenetic analysis based on the 16S rRNA gene and genomes clearly demonstrated that the two strains formed a distinct clade with validly published species of the genus Altererythrobacter. Furthermore, the two strains exhibited distinct phenotypic, physiological and genotypic characteristics that differentiate them from other related type species of the genus Altererythrobacter and related species in the family Erythrobacteraceae. Cells of the two strains were aerobic, Gram-stain negative, non-motile and rod-shaped. Optimal growth conditions for EGI L300112T and EGI L300120 occurred on marine agar 2216 at pH 7 at 30 °C. The major respiratory quinone was Q-10. The detected polar lipids of two strains included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylcholine and unidentified phospholipids. The major fatty acids (>10%) were identified as summed feature 3 (C16 : 1ω7 c/C16 : 1ω6 c) and summed feature 8 (C18 : 1ω7 c). The G+C content of strain EGI L300112T and EGI L300120 was 61.2% and 61.4%, respectively. Based on differential phenotypic and genotypic characteristics of the two strains and related species in the genus Altererythrobacter, the two strains should be classified as representing a new species of this genus, for which the name Altererythrobacter chaiwopuensis sp. nov. is proposed. The type strain is EGI L300112T (=MCCC 1K09432T=KCTC 8712T).