Mucilaginibacter gilvus sp. nov., isolated from Antarctic soil

Biotechnological potential in agriculture of soil Antarctic microorganisms revealed by omics approach

The biotechnological potential for agricultural applications in the soil in the thawing process on Whalers Bay, Deception Island, Antarctica was evaluated using a metagenomic approach through high-throughput sequencing. Approximately 22.70% of the sequences were affiliated to the phyla of the Bacteria dominion, followed by 0.26% to the Eukarya. Proteobacteria (Bacteria) and Ascomycota (Fungi) were the most abundant phyla. Thirty-two and thirty-six bacterial and fungal genera associated with agricultural biotechnological applications were observed. Streptomyces and Pythium were the most abundant genera related to the Bacteria and Oomycota, respectively. The main agricultural application associated with bacteria was nitrogen affixation; in contrast for fungi, was associated with phytopathogenic capabilities. The present study showed the need to use metagenomic technology to understand the dynamics and possible metabolic pathways associated with the microbial communities present in the soil sample in the process of thawing recovered from the Antarctic continent, which presented potential application in processes of agro-industrial interest.

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).

Mucilaginibacter aurantiaciroseus sp. nov. and Mucilaginibacter flavidus sp. nov., isolated from Renlongba glacier on the Tibetan Plateau

Strains RB4R14^T and RT5R15^T, two Gram-stain-negative, aerobic, rod-shaped, non-motile bacteria, were isolated from ice and cryoconite of Renlongba glacier, respectively, on the Tibetan Plateau, PR China. The results of phylogenetic analysis based on 16S rRNA genes indicated that strains RB4R14^T and RT5R15^T belonged to the genus Mucilaginibacter with the highest similarities to Mucilaginibacter rigui WPCB133^T (98.78 %) and Mucilaginibacter xinganensis BJC16-A31^T (97.64 %), respectively. The genomic DNA G+C contents of strains RB4R14^T and RT5R15^T were 42.8 and 43.1 mol%, respectively. The digital DNA-DNA hybridization values between strains RB4R14^T, RT5R15^T and their close relatives were below 31.9 and 17.4 %, respectively. The average nucleotide identity values between the two novel strains and their close relatives were 79.5-82.0 and 77.9-79.3 % respectively, indicating the novelty of the two isolates at a species level. 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 and iso-C_17 : 0-3OH as the major fatty acids. The major polar lipid of the two novel strains were phosphatidylethanolamine. Based on phenotypic, chemotaxonomic and phylogenetic results, we propose two novel species, Mucilaginibacter aurantiaciroseus sp. nov. (RB4R14^T=CGMCC 1.11911^T=NBRC 114020^T) and Mucilaginibacter flavidus sp. nov. (RT5R15^T=CGMCC 1.23117^T=NBRC 113930^T).

Mucilaginibacter segetis sp. nov., Isolated from Soil

A bacterial strain, SD-g^T, was isolated from a soil sample collected on Dokdo Island, South Korea. Cells were observed to be Gram stain negative and short rod shaped, and colonies to be pink in color. Growth of the isolate was observed at 4-30 °C, pH 6-8, and in the presence of 0-2.0% NaCl. Analysis of 16S rRNA gene sequences identified strain SD-g^T as a member of the genus Mucilaginibacter in the family Sphingobacteriaceae, with high levels of sequence similarity with Mucilaginibacter terrenus ZH6^T (96.9%), Mucilaginibacter lutimaris BR-3^T (96.8%), Mucilaginibacter carri PR0008K^T (96.8%), Mucilaginibacter gilvus F01003^T (96.7%), Mucilaginibacter litoreus BR-18^T (96.6%), and Mucilaginibacter terrigena 17JY9-4^T (96.5%). The genomic DNA G+C content of strain SD-g^T was calculated to be 40.6 mol%. The predominant respiratory quinone of the isolate was found to be MK-7; the main polar lipid was phosphatidylethanolamine; and the major fatty acids were identified as summed feature 3 (C_16:1 ω7c/C_16:1 ω6c; 29.0%), C_15:0 iso (19.1%), C_15:0 iso (28.1%), C_16:0 (14.9%), and C_17:0 iso 3-OH (7.4%). The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain SD-g^T and M. terrenus ZH6^T, M. gilvus F01003^T, and M. terrigena ranged from 17.7 to 18.4% and 72.1 to 74.0%, respectively. On the basis of its phenotypic properties, genotypic distinctiveness, and chemotaxonomic features, strain SD-g^T represents a novel species in the genus Mucilaginibacter, for which the name Mucilaginibacter segetis sp. nov. is proposed. The type strain is SD-g^T (= KCTC 82353^T = JCM 34284^T).

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 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.