Modulation of growth, microcystin production, and algal-bacterial interactions of the bloom-forming algae Microcystis aeruginosa by a novel bacterium recovered from its phycosphere

Harmful algal blooms (HABs) in natural waters are of escalating global concern due to their detrimental impact on environmental health. Emerging evidence indicates that algae-bacteria symbionts can affect HAB features, though much about this interplay remains largely unexplored. The current study isolated a new species of Mucilaginibacter (type strain JXJ CY 39T) from culture biomass of the bloom-causing Microcystis aeruginosa FACHB-905 (Maf) from Lake Dianchi, China. Strain JXJ CY 39T was an aerobic, Gram-stain-negative rod bacterium that grew at 5-38°C, pH 4.0-11.0, and 0-3.0% NaCl. Taxonomic evaluation proposed a new species, with Mucilaginibacter lacusdianchii sp. nov., as the species epithet. Experimental results revealed that strain JXJ CY 39T spurred the growth of Maf by supplying soluble phosphorus and nitrogen during cultivation, despite the unavailability of soluble phosphorus and nitrogen. Additionally, by producing the plant hormone indole-3-acetate, strain JXJ CY 39T possibly impacted Maf's functionality. Results from co-culture experiments with other strains from Maf biomass showed possible effects of strain JXJ CY 39T on the relationship between Maf and other cohabiting bacteria, as well as microcystin toxin production characteristics. Although Maf could foster the growth of strain JXJ CY 39T by supplying organic carbon, the strain's growth could be regulated via specific chemical compounds based on antibiotic assays. Community composition analysis disclosed that this Mucilaginibacter strain positively affected Maf's growth and modified densities and types of bacteria linked to Maf. Overall, these results suggest that the interactions between important HAB-causing organisms and their attached bacteria are complex, dynamic, and may influence the growth characteristics of algae.

Whole-Genome Sequence of Mucilaginibacter jinjuensis Strain KACC 16571T

We report the whole-genome sequence of Mucilaginibacter jinjuensis type strain KACC 16571, which was isolated from rotten wood in South Korea. The genome of Mucilaginibacter jinjuensis KACC 16571^T consists of a 6.16-Mb circular chromosome, with a G+C content of 42.1% and 5,262 total predicted coding genes.

Mucilaginibacter straminoryzae sp. nov., isolated from rice straw used for growing periphyton

A rod-shaped, non-motile, Gram-negative bacterium, strain RS28^T, was isolated from rice straw used as material for periphyton growth. Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain RS28^T was affiliated with the genus Mucilaginibacter and had the highest sequence similarity to Mucilaginibacter ginkgonis HMF7856^T (96.47 %) and Mucilaginibacter polytrichastri DSM 26907^T (96.12 %). Strain RS28^T was found to grow at pH 5.5-8.0, 17-40 °C and in the presence of 0-1.5 % (w/v) NaCl. Strain RS28^T contained summed feature 3 (comprising C_16 : 1  ω7c and/or C_16 : 1  ω6c), iso-C_15 : 0 and iso-C_17 : 0 3-OH as the major fatty acids (> 10.0 %). The major polar lipids were phosphatidylethanolamine, two unidentified phospholipids, two unidentified aminophospholipids, three unidentified aminolipids and one unidentified lipid. The respiratory quinone was menaquinone 7. The genomic DNA G+C content was 44.7 mol%. Strain RS28^T possessed six putative secondary metabolite gene clusters involved in the synthesis of resorcinol, NRPS-like, terpene, lassopeptide, T3PKS and arylpolyene. On the basis of the phenotypic, chemotaxonomic, and phylogenetic characteristics, strain RS28^T represents a novel species of the genus Mucilaginibacter, for which the name Mucilaginibacter straminoryzae sp. nov. is proposed. The type strain is RS28^T (=KCTC 92039^T=LMG 32424^T).

Ferruginibacter albus sp. nov., isolated from a mountain soil, and Mucilaginibacter robiniae sp. nov., isolated from a black locust flower, Robinia pseudoacacia

Two bacterial strains, designated KIS38-8T and F39-2T, were isolated from a mountain soil sample and a black locust flower (Robinia pseudoacacia) in Republic of Korea, respectively. The phylogenetic tree based on 16S rRNA gene sequences showed that strain KIS38-8T was classified into the genus Ferruginibacter with the highest sequence similarity to Ferruginibacter lapsinanis HU1-HG42T (96.6 %), and strain F39-2T was grouped into the genus Mucilaginibacter with the highest sequence similarity to Mucilaginibacter daejeonensis Jip 10T (97.6 %). Orthologous average nucleotide identity and digital DNA–DNA hybridization values between strain KIS38-8T and closely related Ferruginibacter strains were less than 72 and 19 %, respectively, while those values between strain F39-2T and closely related Mucilaginibacter strains were less than 73 and 21 %, respectively. The DNA G+C contents of strain KIS38-8T and F39-2T were 36.4 and 41.4 mol%, respectively. On the basis of the phenotypic and genotypic evidence, strains KIS38-8T and F39-2T are considered to represent novel species of the genus Ferruginibacter and Mucilaginibacter , respectively, for which the names Ferruginibacter albus sp. nov. (type strain KIS38-8T=KACC 17328T=NBRC 113101T) and Mucilaginibacter robiniae sp. nov. (type strain F39-2T=KACC 19733T=JCM 33062T) have been proposed.

Identification of Mucilaginibacter conchicola sp. nov., Mucilaginibacter achroorhodeus sp. nov. and Mucilaginibacter pallidiroseus sp. nov. and emended description of the genus Mucilaginibacter

Three chitinolytic, Gram-negative, light pink, capsule-forming, rod-shaped bacterial strains with gliding motion (MYSH2T, MJ1aT and dk17T) were isolated from seashells, soil and foxtail, respectively. Phylogenetic analysis of the 16S rRNA gene sequences and concatenated alignment of 92 core genes indicated that strains MYSH2T, MJ1aT and dk17T were novel species of the genus Mucilaginibacter and exhibited a high 16S rRNA sequence similarity (i.e. more than 97.2 %) among each other. These novel strains contained summed feature 3 (C16:1 ω7c and/or C16:1 ω6), iso-C15:0 and MK-7 as the predominant fatty acids and menaquinone. According to the CAZys coding gene of KAAS, MYSH2T and MJ1aT were interpreted as strains containing both GH18 and 19 family coding genes, except for dk17T, which shows only GH19 family genes. These strains likely degrade chitin to chitobiose or directly to N-acetyl-d-glucosamine, which may enhance their chitinolytic capacity, thus making these stains potentially useful for industrial chitin degradation. Based on distinct morphological, physiological, chemotaxonomic and phylogenetic differences from their closest phylogenetic neighbours, we propose that strains MYSH2T, MJ1aT and dk17T represent three novel species in the genus Mucilaginibacter , for which the names Mucilaginibacter conchicola sp. nov. (=KACC 19716T=JCM 32787T), Mucilaginibacter achroorhodeus sp. nov. (=KACC 19906T=NBRC 113667T) and Mucilaginibacter pallidiroseus sp. nov. (=KACC 19907T=NBRC 113666T) are proposed. An emended description of the genus Mucilaginibacter is proposed.

Mucilaginibacter aquatilis sp. nov., Mucilaginibacter arboris sp. nov., and Mucilaginibacter ginkgonis sp. nov., novel bacteria isolated from freshwater and tree bark

Three Gram-stain-negative, strictly aerobic, non-motile and rod-shaped bacterial strains, designated as HME9299^T, HMF7410^T and HMF7856^T, were isolated from freshwater and tree bark collected in Yong-in, Republic of Korea. Strains HME9299^T, HMF7410^T and HMF7856^T exhibited the highest 16S rRNA gene sequence similarities of 97.2, 94.4 and 96.4 % to Mucilaginibacter daejeonensis Jip 10^T, Mucilaginibacter terrae CCM 8645^T and Mucilaginibacter phyllosphaerae PP-F2F-G21^T, respectively. Among themselves, the values were 94.1-95.7 %. Phylogenetic analysis of the 16S rRNA gene sequences of the three isolates revealed that they belonged to the genus Mucilaginibacter within the family Sphingobacteriaceae. The predominant fatty acids of three strains were summed feature 3 (comprising C_16 : 1  ω7c and/or C_16 : 1  ω6c) and iso-C_15 : 0. Strain HME9299^T contained a relatively large amount of C_16 : 1  ω5c. The predominant respiratory quinone was menaquinone-7. The genome sizes of strains HME9299^T, HMF7410^T and HMF7856^T were 4.33, 4.16 and 3.68 Mbp, respectively, and their DNA G+C contents were 41.6, 38.4 and 43.9 mol%, respectively. Based on the results of the phenotypic, genotypic, chemotaxonomic and phylogenetic investigation, three novel species, Mucilaginibacter aquatilis sp. nov, Mucilaginibacter arboris sp. nov. and Mucilaginibacter ginkgonis sp. nov., are proposed. The type strains are HME9299^T (=KCTC 42122^T=DSM 29146^T), HMF7410^T (=KCTC 62464^T=NBRC 113227^T) and HMF7856^T (=KCTC 72782^T=NBRC 114275^T), respectively.

Mucilaginibacter inviolabilis sp. nov., isolated from the phycosphere of Haematococcus lacustris NIES 144 culture

A Gram-stain-negative, non-motile, rod-shaped, aerobic bacterial strain, designated HC2^T, was isolated from the phycosphere of Haematococcus lacustris NIES 144 culture. Strain HC2^T was able to grow at pH 4.5-8.0, at 4-32 °C and in the presence of 0-2 % (w/v) NaCl. Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain HC2^T was affiliated to the genus Mucilaginibacter and shared the highest sequence similarity with Mucilaginibacter lappiensis ANJKI2^T (98.20 %) and Mucilaginibacter sabulilitoris SMS-12^T (98.06 %). Strain HC2^T contained summed feature 3 (C_16 : 1 ω7c and/or C_16 : 1 ω6c) and iso-C_15 : 0 as the major fatty acids (>10.0 %). The major polar lipids were phosphatidylethanolamine, one unidentified aminophospholipid, one unidentified phospholipid, two unidentified aminolipids and four unidentified lipids. The respiratory quinone was menaquinone 7 (MK-7). The genomic DNA G+C content was 42.0 %. On the basis of the phenotypic, chemotaxonomic and phylogenetic characteristics, strain HC2^T represents a novel species of the genus Mucilaginibacter, for which the name Mucilaginibacter inviolabilis sp. nov. is proposed. The type strain is HC2^T (=KCTC 82084^T=JCM 34116^T).

Mucilaginibacter glaciei sp. nov. and Mucilaginibacter pankratovii sp. nov., isolated from a glacier on the Tibetan Plateau

Two Gram-stain-negative, aerobic, rod-shaped, non-motile, bacterial strains, designated as ZB1P21^T and ZT4R22^T, were isolated from ice and cryoconite samples collected from Zepu glacier on the Tibetan Plateau, PR China. The phylogenetic analysis of 16S rRNA gene showed that the two strains belong to the genus Mucilaginibacter. Strain ZB1P21^T showed the highest similarity to Mucilaginibacter rigui WPCB133^T (97.35 %), while strain ZT4R22^T showed the highest similarity to Mucilaginibacter gilvus F01003^T (99.11 %). The average nucleotide identity values between the two novel strains and their closest relatives were 79.42 and 85.72 % respectively. The two novel strains contained MK-7 as the major menaquinone, and summed feature 3 (comprising C_16 : 1  ω7c and/or C_16 : 1  ω6c), iso-C_15:0, iso-C_17 : 03-OH and C_16 : 1  ω5c as the major fatty acids. The major polar lipid of the two novel strains were phosphatidylethanolamine. Based on these data, we propose two novel species, Mucilaginibacter glaciei sp. nov. (ZB1P21^T=CGMCC 1.23981^T=NBRC 113932^T) and Mucilaginibacter pankratovii sp. nov. (ZT4R22^T=CGMCC 1.23487^T=NBRC 113931^T).

Mucilaginibacter agri sp. nov. and Mucilaginibacter humi sp. nov., isolated from soil

Two Gram-stain-negative, facultative anaerobic and non-motile bacteria, strains R11T and S1162T, were isolated from soil in the Republic of Korea. Both strains were catalase- and oxidase-positive and contained menaquinone-7 as the major isoprenoid quinone. Strain R11T contained summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), iso-C15:0, C16:0 and iso-C17:0 3-OH as major fatty acids and phosphatidylethanolamine, an unidentified aminophospholipid and an unidentified aminolipid as major polar lipids; while strain S1162T contained summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), iso-C15:0, iso-C17:0 3-OH, C16:0 and summed feature 9 (10-methyl C16:0 and/or iso-C17:1 ω9c) as major fatty acids and phosphatidylethanolamine and an unidentified aminophospholipid as major polar lipids. The DNA G+C contents of strains R11T and S1162T calculated from their whole genomes were 42.7 and 42.9 mol%, respectively. Results of phylogenetic analysis based on 16S rRNA gene sequences showed that strain R11T formed a phylogenetic lineage with Mucilaginibacter jinjuensis YC7004T and strain S1162T formed a distinct phyletic lineage from closely related type strains within the genus Mucilaginibacter . Strains R11T and S1162T were most closely related to M. jinjuensis YC7004T and Mucilaginibacter panaciglaebae BXN5-31T with 97.78 and 97.23% 16S rRNA gene sequence similarities, respectively. On the basis of phenotypic, chemotaxonomic and molecular analysis, strains R11T and S1162T represent two novel species of the genus Mucilaginibacter , for which the names Mucilaginibacter agri sp. nov. and Mucilaginibacter humi sp. nov. are proposed, respectively. The type strains of M. agri and M. humi are R11T (=KACC 21228T=JCM 33472T) and S1162T (=KACC 21669T=JCM 33916T), respectively.

An assessment of the genomics, comparative genomics and cellulose degradation potential of Mucilaginibacter polytrichastri strain RG4-7

In this study, whole genome sequencing and comparative genomic analyses were performed for Mucilaginibacter polytrichastri RG4-7 and its carboxymethyl cellulose degradation potential was assessed. The results showed that the genome of strain RG4-7 was 5.84 Mb and contained 5019 predicted genes, in which a high proportion of strain-specific genes were related to carbohydrate metabolism. The carboxymethyl cellulose (CMC) degradation and cellulase activity tests revealed the strong cellulose degradation ability, CMCase and β-glucosidase activity in strain RG4-7. Real-time RT-PCR testing of most cellulose degradation related glycoside hydrolase (GH) families showed that GH9 (OKS85969), GH1 (OKS85832), GH3 (OKS89331 and OKS85615) were significantly up-regulated when strain RG4-7 was inoculated with CMC-Na, which suggested that GH9, GH1 and GH3 might determine its cellulose degradation ability. Certainly, further research need to be done to elucidate cellulose degradation mechanisms in strain RG4-7 in order to develop its industrial application value in lignocellulosic biomass degradation and waste management.

Mucilaginibacter corticis sp. nov., isolated from bark of Pinus koraiensis

A gram-stain negative, aerobic, non-motile and rod-shaped novel bacterial strain, designated MAH-19^T, was isolated from bark of Pinus koraiensis. The colonies were observed to be light pink coloured, smooth, circular and 0.3-0.7 mm in diameter when grown on R2A agar for 2 days. Strain MAH-19^T was found to be able to grow at 10-35 °C (optimum 28-30 °C), at pH 6.0-8.0 (optimum 7.0) and at 0-0.5% NaCl (optimum 0%). Cell growth occurs on nutrient agar and R2A agar. The strain was found to be positive for both catalase and oxidase tests. Cells are able to hydrolyse aesculin and Tween 20, but not casein, gelatin, starch, L-tyrosine, DNA, L-arginine, urea or Tween 80. According to the 16S rRNA gene sequence comparisons, the isolate was identified as a member of the genus Mucilaginibacter and to be closely related to Mucilaginibacter panaciglaebae BXN5-31^T (97.4% similarity), Mucilaginibacter antarcticus S14-88^T (97.2%) and Mucilaginibacter ximonensis XM-003^T (97.1%). In DNA-DNA hybridization tests, the DNA relatedness between strain MAH-19^T and its close phylogenetic neighbours was below 45.0%. The novel strain MAH-19^T has a draft genome size of 5,335,442 bp (14 contigs), annotated with 4963 protein-coding genes, 44 tRNA and 6 rRNA genes. The genomic DNA G+C content was determined to be 42.7 mol%. The predominant isoprenoid quinone of strain MAH-19^T was identified as MK-7. The major fatty acids were identified as C_{15:0 iso} and summed feature 3 (comprising C_16:1ω7c and/or C_16:1ω6c). The DNA-DNA hybridization results and results of the genotypic analysis, in combination with chemotaxonomic and physiological data, demonstrated that strain MAH-19^T represents a novel species within the genus Mucilaginibacter, for which the name Mucilaginibacter corticis sp. nov. is proposed, with MAH-19^T (= KACC 19745^T = CGMCC1.13657^T) as the type strain.

Analysis of 1,000 Type-Strain Genomes Improves Taxonomic Classification of Bacteroidetes

Although considerable progress has been made in recent years regarding the classification of bacteria assigned to the phylum Bacteroidetes, there remains a need to further clarify taxonomic relationships within a diverse assemblage that includes organisms of clinical, piscicultural, and ecological importance. Bacteroidetes classification has proved to be difficult, not least when taxonomic decisions rested heavily on interpretation of poorly resolved 16S rRNA gene trees and a limited number of phenotypic features. Here, draft genome sequences of a greatly enlarged collection of genomes of more than 1,000 Bacteroidetes and outgroup type strains were used to infer phylogenetic trees from genome-scale data using the principles drawn from phylogenetic systematics. The majority of taxa were found to be monophyletic but several orders, families and genera, including taxa proposed long ago such as Bacteroides, Cytophaga, and Flavobacterium but also quite recent taxa, as well as a few species were shown to be in need of revision. According proposals are made for the recognition of new orders, families and genera, as well as the transfer of a variety of species to other genera. In addition, emended descriptions are given for many species mainly involving information on DNA G+C content and (approximate) genome size, both of which can be considered valuable taxonomic markers. We detected many incongruities when comparing the results of the present study with existing classifications, which appear to be caused by insufficiently resolved 16S rRNA gene trees or incomplete taxon sampling. The few significant incongruities found between 16S rRNA gene and whole genome trees underline the pitfalls inherent in phylogenies based upon single gene sequences and the impediment in using ordinary bootstrapping in phylogenomic studies, particularly when combined with too narrow gene selections. While a significant degree of phylogenetic conservation was detected in all phenotypic characters investigated, the overall fit to the tree varied considerably, which is one of the probable causes of misclassifications in the past, much like the use of plesiomorphic character states as diagnostic features.

Mucilaginibacter hurinus sp. nov., isolated from briquette warehouse soil

A novel bacterial strain, designated ZR32^T, was isolated from briquette warehouse soil in Ulsan (Korea). The strain was aerobic, showing pink-colored colonies on R2A agar. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain ZR32^T was closely related to Mucilaginibacter soli R9-65^T (97.0%), Mucilaginibacter gynuensis YC7003^T (96.9%), and Mucilaginibacter lutimaris BR-3^T (96.8%). The values of DNA-DNA relatedness related two highest strains M. soli R9-65^T and M. gynuensis YC7003^T were 31.2 ± 6.9% and 19.7 ± 0.3%, respectively. Its genome size was 3.9 Mb, comprising 3402 predicted genes. The DNA G+C content of strain ZR32^T was 43.0 mol%. The major cellular fatty acids (> 5% of total) were summed feature 3 (C_16:1ω6c and/or C_16:1ω7c), C_16:0, C_16:1ω5c, iso-C_15:0, iso-C_17:0 3-OH, and C_17:1ω9c. The major respiratory quinine was menaquinone-7 (MK-7). The major polar lipids were phosphatidylethanolamine, two unidentified phospholipids, one unidentified sphingolipid, and one unidentified polar lipid. Strain ZR32^T showed distinctive characteristics such as the temperature and pH for growth ranges, being positive for β-glucosidase, salicin production, negative for N-acetyl-glucosamine assimilation, being resistant to carbenicillin and piperacillin to related species. On the basis of phenotypic, chemotaxonomic, and phylogenetic data, strain ZR32^T represents a novel species of the genus Mucilaginibacter, for which the name Mucilaginibacter hurinus sp. nov. is proposed. The type strain is ZR32^T (= KCTC 62193 = CCTCC AB 2017285).

Mucilaginibacter terrigena sp. nov. sp., A Novel Member of the Family Sphingobacteriaceae

A bacterial strain, 17JY9-4^T, was isolated from a soil sample collected on Jeju Island, South Korea. Colonies grown on R2A agar are pale pink in color, and cells are Gram-stain negative, short, and rod-shaped. Analysis of 16S rRNA gene sequences identified this strain as a member of the genus Mucilaginibacter in the family Sphingobacteriaceae, with high levels of 16S rRNA sequence similarity shared with Mucilaginibacter lutimaris BR-3^T (98.0%), Mucilaginibacter rigui WPCB133^T (98.0%), Mucilaginibacter phyllosphaerae PP-F2F-G21^T (97.0%), Mucilaginibacter amnicola TAPP7^T (96.8%), and Mucilaginibacter soli R9-65^T (96.7%). Growth of strain 17JY9-4^T occurs at 10-30 °C, pH 6-8, and in the presence of 0-1.0% NaCl. The genomic G+C content is 44.38 mol%. The predominant respiratory quinone of the isolate is MK-7; the major fatty acids are summed feature 3 (C_16:1ω7c/C_16:1ω6c) (39.7%), iso-C_15:0 (22.8%), iso-C_17:0 3-OH (7.8%), and C_16:0 (7.7%); and the major polar lipid is phosphatidylethanolamine. The phenotypic and chemotaxonomic data support the placement of strain 17JY9-4^T within the genus Mucilaginibacter. However, the DNA-DNA relatedness between the isolate and M. rigui, M. lutimaris, M. phyllosphaerae, M. amnicola, and M. soli were 44.3 ± 3.0%, 38.6 ± 3.7%, 23.2 ± 2.9%, 21.9 ± 3.1%, and 18.6 ± 3.7%, respectively. The results of 16S rRNA gene sequence similarity analysis, DNA-DNA hybridization analysis, and the observed differentiating phenotypic properties from other closely related taxa clearly indicate that strain 17JY9-4^T represents a novel species in the genus Mucilaginibacter, for which the name Mucilaginibacter terrigena sp. nov. is proposed. The type strain is 17JY9-4^T (= KCTC 62294^T = JCM 33049^T).

Mucilaginibacter formosus sp. nov., a bacterium isolated from road-side soil

A Gram-stain negative, aerobic, non-motile and rod-shaped novel bacterial strain, designated as MAH-5^T, was isolated from a road-side soil sample and was characterised by using a polyphasic taxonomic approach. The colonies were observed to be yellowish orange in colour, smooth, circular and 0.3-0.7 mm in diameter when grown on nutrient agar for 2 days. Strain MAH-5^T was found to be able to grow at 15-35 °C and at pH 4.0-8.0. The strain was observed to be positive for both the catalase and oxidase tests. Cells were found to be able to hydrolyse aesculin, gelatin and starch. By 16S rRNA gene sequence comparisons, the isolate was identified as a member of the genus Mucilaginibacter and to be closely related to Mucilaginibacter panaciglaebae BXN5-31^T (98.35%), Mucilaginibacter soyangensis HME6664^T (97.82%), Mucilaginibacter antarcticus S14-88^T (97.49%) and Mucilaginibacter ximonensis XM-003^T (97.06%). In DNA-DNA hybridization tests, the DNA relatedness values between strain MAH-5^T and its close phylogenetic neighbors were below 45.0%. The genomic DNA G + C content of strain MAH-5^T was determined to be 41.5 mol% and the predominant isoprenoid quinine was identified as MK-7. The major fatty acids were identified as C_{15:0 iso} and summed feature 3 (comprising C_16:1ω7c and/or C_16:1ω6c). The genetic characteristics, in combination with chemotaxonomic and physiological data, demonstrated that the isolated strain MAH-5^T represents a novel species within the genus Mucilaginibacter, for which the name Mucilaginibacter formosus sp. nov. is proposed, with MAH-5^T as the type strain (= KACC 19291^T = CGMCC1.16489^T).

Mucilaginibacter ginsenosidivorans sp. nov., Isolated from Soil of Ginseng Field

A Gram-reaction-negative, aerobic, nonmotile, nonspore-forming, and rod-shaped bacterial strain designated Gsoil 3017^T was isolated from soil of ginseng field and investigated by phenotypic and phylogenetic analyses. Strain Gsoil 3017^T grew at 10-37 °C (optimal growth at 30 °C) and at pH 5.5-8.0 (optimal growth at pH 7) on R2A and nutrient agar without additional NaCl as a supplement. Strain Gsoil 3017^T possessed β-glucosidase activity, which was responsible for its ability to transform ginsenosides Rb₁, Rc, and Rd (the three dominant active components of ginseng) to F₂ and C-K, respectively. Based on 16S rRNA gene phylogeny, the novel strain represents a new branch within the genus Mucilaginibacter family Sphingobacteriaceae, and clusters with Mucilaginibacter frigoritolerans FT22^T (95.6%) and Mucilaginibacter gotjawali SA3-7^T (95.6%). The G+C content of the genomic DNA was 48.7%. The predominant respiratory quinone was MK-7, and the major fatty acids were iso-C_15:0, iso-C_17:0 3-OH, and summed feature 3 (comprising C_16:1 ω6c and/or C_16:1 ω7c). The major polar lipid was phosphatidylethanolamine. Strain Gsoil 3017^T could be differentiated genotypically and phenotypically from other type strains of the genus Mucilaginibacter. The isolate therefore represents a novel species, for which the name Mucilaginibacter ginsenosidivorans sp. nov. is proposed, with the type strain Gsoil 3017^T (=KACC 14954^T = JCM 17081^T).

Mucilaginibacter ginsenosidivorans sp. nov., Isolated from Soil of Ginseng Field

A Gram-reaction-negative, aerobic, nonmotile, nonspore-forming, and rod-shaped bacterial strain designated Gsoil 3017^T was isolated from soil of ginseng field and investigated by phenotypic and phylogenetic analyses. Strain Gsoil 3017^T grew at 10-37 °C (optimal growth at 30 °C) and at pH 5.5-8.0 (optimal growth at pH 7) on R2A and nutrient agar without additional NaCl as a supplement. Strain Gsoil 3017^T possessed β-glucosidase activity, which was responsible for its ability to transform ginsenosides Rb₁, Rc, and Rd (the three dominant active components of ginseng) to F₂ and C-K, respectively. Based on 16S rRNA gene phylogeny, the novel strain represents a new branch within the genus Mucilaginibacter family Sphingobacteriaceae, and clusters with Mucilaginibacter frigoritolerans FT22^T (95.6%) and Mucilaginibacter gotjawali SA3-7^T (95.6%). The G+C content of the genomic DNA was 48.7%. The predominant respiratory quinone was MK-7, and the major fatty acids were iso-C_15:0, iso-C_17:0 3-OH, and summed feature 3 (comprising C_16:1 ω6c and/or C_16:1 ω7c). The major polar lipid was phosphatidylethanolamine. Strain Gsoil 3017^T could be differentiated genotypically and phenotypically from other type strains of the genus Mucilaginibacter. The isolate therefore represents a novel species, for which the name Mucilaginibacter ginsenosidivorans sp. nov. is proposed, with the type strain Gsoil 3017^T (=KACC 14954^T = JCM 17081^T).

Mucilaginibacterpsychrotolerans sp. nov., isolated from peatlands

A Gram-stain-negative, rod-shaped, non-flagellated, pink, cold-tolerant bacterial strain, NH7-4T, was isolated from the Riganqiao peatlands on the Tibetan Plateau. The 16S rRNA gene sequence of the novel isolate shared a pairwise similarity ranging from 96.84 to 93.02 % with type strains of species of the genus Mucilaginibacter. Growth of strain NH7-4T occurred between 0 and 30 °C and at pH 5.0-9.0, with an optimum growth temperature at 20 °C and an optimum pH for growth of approximately 7.0. The major isoprenoid quinone was MK-7. The major cellular fatty acids were summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH), iso-C15 : 0, iso-C17 : 0 3-OH, C16 : 0, iso-C15 : 0 3-OH and C16 : 1ω5c. The major polar lipid of strain NH7-4T was phosphatidylethanolamine. Strain NH7-4T did not assimilate any substrates in API 20NE strips without low concentrations of yeast extract being present and had a lower optimal growth temperature, which distinguished it from other type strains of species of the genus Mucilaginibacter. The DNA G+C content of strain NH7-4T was 48.6 mol%. Based on phylogenetic, phenotypic and chemotaxonomic data, strain NH7-4T (=JCM 30607T=CGMCC1.14937T) represents a novel species of the genus Mucilaginibacter for which the name Mucilaginibacter psychrotolerans sp. nov. is proposed.

Mucilaginibacter ginsengisoli sp. nov., isolated from a ginseng-cultivated soil

A dark-pink-coloured bacterial strain, B4Y-8T, was isolated from a soil cultivated with ginseng. The 16S rRNA gene sequence of this strain showed highest similarity with Mucilaginibacter litoreus BR-18T (96.8 %), Mucilaginibacter lutimaris BR-3T (96.6 %) and Mucilaginibacter defluvii A5T (96.2 %) among the type strains of species of the genus Mucilaginibacter. Strain B4Y-8T was a strictly aerobic, Gram-stain-negative, non-motile, short-rod-shaped bacterium producing a large amount of extracellular polymeric substance. The strain grew at 10–35 °C (optimum, 25 °C), at pH 3.0–11.0 (optimum, pH 7.0) and in the presence of 0–1 % (w/v) NaCl (optimum, 0 %). The DNA G+C content of strain B4Y-8T was 49.0 mol%. It contained menaquinone 7 (MK-7) as the major isoprenoid quinone, and summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c) and iso-C15 : 0 as the major fatty acids. On the basis of evidence from the present polyphasic taxonomic study, strain B4Y-8T should be classified as representing a novel species of the genus Mucilaginibacter, for which the name Mucilaginibacter ginsengisoli sp. nov. is proposed. The type strain is B4Y-8T ( = KACC 18152T = JCM 30759T).

Mucilaginibacter aquaedulcis sp. nov., isolated from fresh water

An aerobic, Gram-stain-negative, rod-shaped bacterium, designated strain PGW1-R01T, was isolated from fresh water from the Yeongju in the Republic of Korea. The strain grew optimally at 30 °C and at pH 6-8 on R2A agar. The major cellular fatty acids were summed feature 3 [comprising C16 : 1ω7c and/or C16 : 1ω6c (50.2 %) and iso-C15 : 0 (24.8 %)]. The major respiratory quinone was MK-7. The G+C contents were 39.4 mol% and the predominant respiratory quinone was MK-7. Based on 16S rRNA gene phylogeny, the strain belongs to the genus Mucilaginibacter . The strain PGW1-R01T was closely related to ‘ Mucilaginibacter ginsenosidivorax’ (96.6 % sequence similarity), Mucilaginibacter lappiensis (96.4 %) and Mucilaginibacter flavus (96.4 %). On the basis of the evidence presented in this study, strain PGW1-R01T represents a novel species of the genus Mucilaginibacter , for which the name Mucilaginibacter http://dx.doi.org/10.1601/nm.11437 aquaedulcis sp. nov., is proposed. The type strain is PGW1-R01T( = KCTC 23942T = CECT 8102T).