Hymenobacter jeollabukensis sp. nov., isolated from soil

Isolation and characterization of two new species, Hymenobacter mellowenesis sp. nov. and Hymenobacter aranciens sp. nov., from soil

Strains M29T and ASUV-10-1T, which are aerobic, non-flagellated, and Gram-stain-negative, were isolated from soil samples collected in Inje (37°57'49.1"N 128°19'53.7"E) and Cheonan City (36°48'47.1"N 127°05'22.4"E), South Korea. Phylogenetic analyses based on rRNA gene sequences revealed that strains M29T and ASUV-10-1T form a distinct branch within the family Hymenobacter (order Cytophagales, class Cytophagia). Strain M29T is most closely related to Hymenobacter rubidus DG7BT with a 16 S rRNA gene sequence similarity of 97.05%. Strain ASUV-10-1T shows closest genetic similarity to Hymenobacter frigidus B1789T (96.42%), Hymenobacter jeongseonensis BT683T (95.97%), and Hymenobacter terricola 3F2TT (95.65%). The optimal growth conditions for these strains are pH 7.0, no NaCl, and a temperature of 25 °C. The dominant cellular fatty acids identified in these strains are iso-C15:0, anteiso-C15:0, and Summed Feature 3 (C16:1ω 7c / C16:1ω 6c). Both strains predominantly contain MK-7 as the respiratory quinone. The major polar lipids in strains M29T and ASUV-10-1T are phosphatidylethanolamine, aminophospholipid, and aminolipid. Based on biochemical, chemotaxonomic, and phylogenetic data, it is evident that M29T and ASUV-10-1T represent new species within the genus Hymenobacter. The new species were classified based on biochemical and chemotaxonomic characteristics. The taxonomic classification of these species was conducted following the guidelines and protocols outlined in Bergey's Manual of Systematic Bacteriology. We followed the methods for determining physiological and biochemical characteristics, as well as chemotaxonomic markers such as fatty acid profiles, quinone types, and polar lipid compositions. We also compared with the results of carbohydrate utilization and enzyme activities results [Bergey 1994]. Therefore, we propose the names Hymenobacter mellowenesis for strain M29T (= KCTC 102056T = NBRC 116578T) and Hymenobacter aranciens for strain ASUV-10-1T (= KCTC 92969T = NBRC 116575T).

Hymenobacter canadensis sp. nov., isolated from freshwater of the pond in Cambridge Bay, Canada

A Gram-stain-negative, aerobic, reddish-coloured, rod-shaped and non-motile strain PAMC 29467^T, was isolated from freshwater of the pond in Cambridge Bay, Canada. Strain PAMC 29467^T was closely related to Hymenobacter yonginensis (98.1 % 16S rRNA gene similarity). Genomic relatedness analyses showed that strain PAMC 29467^T is distinguishable from H. yonginensis based on average nucleotide identity (91.3 %) and digital DNA-DNA hybridization values (39.3 %). The major fatty acids (>10 %) of strain PAMC 29467^T were summed feature 3 (C_16 : 1  ω7c and/or C_16 : 1  ω6c), C_15 : 0 iso, C_16 : 1  ω5c and summed feature 4 (C_17 : 1 iso l and/or anteiso B). The major respiratory quinone was menaquinone-7. The genomic DNA G+C content was 61.5 mol%. Strain PAMC 29467^T was separated from the type species in the genus Hymenobacter by its distinct phylogenetic position and some physiological characteristics. As a result, a novel species is proposed, with the name Hymenobacter canadensis sp. nov. (type strain, PAMC 29467^T=KCTC 92787^T=JCM 35843^T).

Compositional Data Analysis of 16S rRNA Gene Sequencing Results from Hospital Airborne Microbiome Samples

The compositional analysis of 16S rRNA gene sequencing datasets is applied to characterize the bacterial structure of airborne samples collected in different locations of a hospital infection disease department hosting COVID-19 patients, as well as to investigate the relationships among bacterial taxa at the genus and species level. The exploration of the centered log-ratio transformed data by the principal component analysis via the singular value decomposition has shown that the collected samples segregated with an observable separation depending on the monitoring location. More specifically, two main sample clusters were identified with regards to bacterial genera (species), consisting of samples mostly collected in rooms with and without COVID-19 patients, respectively. Human pathogenic genera (species) associated with nosocomial infections were mostly found in samples from areas hosting patients, while non-pathogenic genera (species) mainly isolated from soil were detected in the other samples. Propionibacterium acnes, Staphylococcus pettenkoferi, Corynebacterium tuberculostearicum, and jeikeium were the main pathogenic species detected in COVID-19 patients' rooms. Samples from these locations were on average characterized by smaller richness/evenness and diversity than the other ones, both at the genus and species level. Finally, the ρ metrics revealed that pairwise positive associations occurred either between pathogenic or non-pathogenic taxa.

Hymenobacter edaphi sp. nov., isolated from abandoned arsenic-contaminated farmland soil

A Gram-stain-negative, aerobic, rod-shaped, non-motile, pink-pigmented bacterium, designated NL^T, was isolated from arsenic-contaminated farmland soil. Strain NL^T showed the highest 16S rRNA gene sequence similarities with those of Hymenobacter jeollabukensis 1-3-3-8^T (98.9 %), Hymenobacter gummosus ANT-18^T (97.5 %), Hymenobacter paludis KBP-30^T (97.4 %), Hymenobacter ocellatus Myx2105^T (97.1 %) and Hymenobacter coalescens WW84^T (96.4 %). The values of genomic orthoANI and dDDH between strain NL^T and Hymenobacter jeollabukensis KCTC 52741^T was 90.5 and 41.2 %, respectively, and those between strain NL^T and Hymenobacter gummosus KCTC 52166^T was 84.4 and 28.4 %, respectively. Strain NL^T exhibited DNA-DNA hybridisation values of 41.3 and 44.1 % with Hymenobacter paludis KCTC 32237^T and Hymenobacter ocellatus DSM 11117^T, respectively. Strain NL^T had major fatty acids (>10 %) of summed feature 4 (iso-C_17 : 1 I and/or anteiso-C_17 : 1 B), iso-C_15 : 0 and anteiso-C_15 : 0 and the predominant polyamine of homospermidine. The only respiratory quinone was menaquinone-7. The polar lipids were phosphatidylethanolamine, phospholipid, three unidentified lipids and two amino lipids. Strain NL^T had a genome size of 6.04 Mb and the average G+C content of 65.6 %. Compared to the other Hymenobacter spp., strain NL^T is different in polar lipid profile (without aminophospholipid) and leucine arylamidase activity. Based on the data of the polyphasic analysis, it is considered that strain NL^T represented a novel species of genus Hymenobacter, for which the name Hymenobacter edaphisp. nov. is proposed. The type strain is NL^T (=KCTC 62521^T=CCTCC AB 2018028^T).

Hymenobacter oligotrophus sp. nov., isolated from a contaminated agar plate

A taxonomic study of a Gram-stain negative, rod-shaped, motile, asporogenous, catalase- and oxidase-positive bacterium, sh-6^T, forming pink-red colonies, isolated from a contaminated R2A plate in the laboratory was performed. Its optimum growth temperature was determined to be 28 °C in the absence of NaCl on R2A plates. On the basis of 16S rRNA gene sequence analysis, strain sh-6^T belongs to the genus Hymenobacter and is closely related to Hymenobacter deserti ZLB-3^T (95.05%), Hymenobacter paludis KBP-30^T (94.96%), Hymenobacter coalescens WW84^T (94.04%), Hymenobacter gummosus ANT-18^T (93.38%), Hymenobacter ocellatus Myx2105^T (93.70%), Hymenobacter jeollabukensis 1-3-3-8^T (93.48%) and Hymenobacter koreensis GYR3077^T (93.21%). Comparison of the genome of strain sh-6^T and that of H. gummosus ANT-18^T gave digital DNA-DNA hybridization and Average Nucleotide Identity values of 20.6% and 78.4%, respectively. The respiratory isoprenoid quinone and polyamine component were identified as MK-7 and sym-homospermidine, respectively. The major cellular fatty acids identified as iso-C_15:0, summed feature 4 (iso-C_17:1 I/anteiso B), iso-C_16:0, iso-C_17:0 3-OH and iso-C_17:0. The major polar lipid of strain sh-6^T determined to be phosphatidylethanolamine. The DNA G+C content was determined to be 60.5 mol%. On the basis of the evidence presented in this study, a novel species of the genus Hymenobacter, Hymenobacter oligotrophus sp. nov., is proposed, with the type strain sh-6^T (= CCTCC AB 2016064^T = KCTC 62345^T).