Protaetiibacter mangrovi sp. nov., isolated from mangrove soil.

A novel Gram-stain-positive, aerobic, non-flagellated and rod-shaped actinobacterium, designated 10F1B-8-1T, was isolated from mangrove soil sampled at Futian Mangrove Nature Reserve, China. The isolate was able to grow at 10-40 °C (optimum 30-32 °C), at pH 6-8 (optimum 7) and in the presence of 0-6% (w/v) NaCl (optimum 0%). Strain 10F1B-8-1T shared the highest 16S rRNA gene sequence similarity to Protaetiibacter larvae NBRC 113051T (98.3%), followed by Protaetiibacter intestinalis NBRC 113050T (98.2%). Phylogenetic trees based on 16S rRNA gene sequences and the core proteomes exhibited that strain 10F1B-8-1T formed a new phyletic line in the clade of genus Protaetiibacter, indicating that this strain belonged to the genus Protaetiibacter. Strain 10F1B-8-1T showed low average nucleotide identity (<84%) and digital DNA-DNA hybridization values (<27%) with closely related taxa, suggesting that strain 10F1B-8-1T was a hitherto undescribed species of the genus Protaetiibacter. Strain 10F1B-8-1T contained D-2,4-diaminobutyric acid as the diagnostic diamino acid, and the peptidoglycan type was characterized as type B2ß. The major fatty acids were iso-C16:0, anteiso-C15:0 and anteiso-C17:0. The major menaquinones were MK-13 and MK-14. The polar lipid profile included diphosphatidylglycerol, phosphatidylglycerol, an unidentified glycolipid and five unidentified lipids. Notably, the ethyl acetate extracts of strain 10F1B-8-1T showed effective antibacterial activity against Bacillus subtilis CPCC 100029 and Escherichia coli △tolC. According to the polyphasic data, strain 10F1B-8-1T should be classified as a novel species of the genus Protaetiibacter, for which the name Protaetiibacter mangrovi sp. nov. is proposed, with the type strain 10F1B-8-1T (=JCM 33142T = CPCC 205428T).

Isolation, Structure Elucidation, and First Total Synthesis of Quinomycins K and L, Two New Octadepsipeptides from the Maowei Sea Mangrove-Derived Streptomyces sp. B475.

Mangrove actinomycetia have been proven to be one of the promising sources for discovering novel bioactive natural products. Quinomycins K (1) and L (2), two rare quinomycin-type octadepsipeptides without intra-peptide disulfide or thioacetal bridges, were investigated from the Maowei Sea mangrove-derived Streptomyces sp. B475. Their chemical structures, including the absolute configurations of their amino acids, were elucidated by a combination of NMR and tandem MS analysis, electronic circular dichroism (ECD) calculation, advanced Marfey's method, and further unequivocally confirmed by the first total synthesis. The two compounds displayed no potent antibacterial activity against 37 bacterial pathogens and had no significant cytotoxic activity against H460 lung cancer cells.

Bioprospecting of desert actinobacteria with special emphases on griseoviridin, mitomycin C and a new bacterial metabolite producing Streptomyces sp. PU-KB10-4.

BACKGROUND: Bioprospecting of actinobacteria isolated from Kubuqi desert, China for antibacterial, antifungal and cytotoxic metabolites production and their structure elucidation. RESULTS: A total of 100 actinobacteria strains were selectively isolated from Kubuqi desert, Inner Mongolia, China. The taxonomic characterization revealed Streptomyces as the predominant genus comprising 37 different species, along with the rare actinobacterial genus Lentzea. The methanolic extracts of 60.8% of strains exhibited potent antimicrobial activities against Staphylococcus aureus, Micrococcus luteus, Bacillus subtilis, Escherichia coli, Salmonella enterica, Saccharomyces cerevisiae and high to mild in vitro cytotoxicity against PC3 (prostate cancer) and A549 (lung carcinoma) cell lines. The metabolomics analysis by TLC, HPLC-UV/vis, HPLC-MS and NMR showed the presence of compounds with molecular weights ranging from 100 to 1000 Da. The scale-up fermentation of the prioritized anti-Gram-negative strain PU-KB10-4 (Streptomyces griseoviridis), yielded three pure compounds including; griseoviridin (1; 42.0 mgL- 1) with 20 fold increased production as compared to previous reports and its crystal structure as monohydrate form is herein reported for the first time, mitomycin C (2; 0.3 mgL- 1) and a new bacterial metabolite 4-hydroxycinnamide (3; 0.59 mgL- 1). CONCLUSIONS: This is the first report of the bioprospecting and exploration of actinobacteria from Kubuqi desert and the metabolite 4-hydroxycinnamide (3) is first time isolated from a bacterial source. This study demonstrated that actinobacteria from Kubuqi desert are a potential source of novel bioactive natural products. Underexplored harsh environments like the Kubuqi desert may harbor a wider diversity of actinobacteria, particularly Streptomyces, which produce unique metabolites and are an intriguing source to develop medicinally valuable natural products.

Schumannella soli sp. nov., a novel actinomycete isolated from mangrove soil by in situ cultivation.

A novel actinobacterial strain, designated 10F1D-1T, was isolated from soil sample collected from Futian mangrove nature reserve, China using of the in situ cultivation technique. Preliminary analysis based on the 16S rRNA gene sequence revealed that strain 10F1D-1T was the member of genus Schumannella with sharing highest sequence similarity (99.7%) to Schumannella luteola DSM 23141T. Phylogenetic analyses based on 16S rRNA gene sequences and core proteome consistently exhibited that strain 10F1D-1T formed a monophyletic clade with Schumannella luteola DSM 23141T. Comparative genomic analyses clearly separated strain 10F1D-1T from the only species of the genus Schumannella based on average nucleotide identity (ANI), average amino acid identity (AAI) and digital DNA-DNA hybridization (dDDH) values below the thresholds for species delineation. The genome of strain 10F1D-1T contains the biosynthetic gene clusters for osmoprotectants to adapt to the salt environment of mangrove. Strain 10F1D-1T also contains the biosynthetic gene clusters for bioactive compounds as secondary metabolites. On the basis of the polyphasic analysis, strain 10F1D-1T is considered to represent a novel species of the genus Schumannella, for which the name Schumannella soli sp. nov. (type strain 10F1D-1T = CGMCC1.16699T = JCM 33146T) is proposed.

Characterization and description of Faecalibacterium butyricigenerans sp. nov. and F. longum sp. nov., isolated from human faeces.

Exploiting a pure culture strategy to investigate the composition of the human gut microbiota, two novel anaerobes, designated strains AF52-21T and CM04-06T, were isolated from faeces of two healthy Chinese donors and characterized using a polyphasic approach. The two strains were observed to be gram-negative, non-motile, and rod-shaped. Both strains grew optimally at 37 °C and pH 7.0. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the two strains clustered with species of the genus Faecalibacterium and were most closely related to Faecalibacterium prausnitzii ATCC 27768T with sequence similarity of 97.18% and 96.87%, respectively. The two isolates shared a 16S rRNA gene sequence identity of 98.69%. Draft genome sequencing was performed for strains AF52-21T and CM04-06T, generating genome sizes of 2.85 Mbp and 3.01 Mbp. The calculated average nucleotide identity values between the genomes of the strains AF52-21T and CM04-06T compared to Faecalibacterium prausnitzii ATCC 27768T were 83.20% and 82.54%, respectively, and 90.09% when comparing AF52-21T and CM04-06T. Both values were below the previously proposed species threshold (95-96%), supporting their recognition as novel species in the genus Faecalibacterium. The genomic DNA G + C contents of strains AF52-21T and CM04-06T calculated from genome sequences were 57.77 mol% and 57.51 mol%, respectively. Based on the phenotypic, chemotaxonomic and phylogenetic characteristics, we conclude that both strains represent two new Faecalibacterium species, for which the names Faecalibacterium butyricigenerans sp. nov. (type strain AF52-21T = CGMCC 1.5206T = DSM 103434T) and Faecalibacterium longum sp. nov. (type strain CM04-06T = CGMCC 1.5208T = DSM 103432T) are proposed.

Metabolomic Approach for Characterization of Polyphenolic Compounds in Laminaria japonica, Undaria pinnatifida, Sargassum fusiforme and Ascophyllum nodosum.

Profiling of polyphenolics in four types of brown macroalgae, namely Laminaria japonica (L. japonica), Undaria pinnatifida (U. pinnatifida), Sargassum fusiforme (S. fusiforme), and Ascophyllum nodosum (A. nodosum), and their effect on oxidation resistance were investigated for the first time. Polyphenolic extracts from marine brown macroalgae were shown to effectively remove oxidants from cells and cellular systems. A. nodosum showed the highest antioxidant activity among evaluated brown macroalgae, showing a better scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical and alleviating oxidative damage caused by hydrogen peroxide to human keratinocytes (HaCaT) cells. Through Q-Exactive HF-X mass spectrometry analysis, 12 polyphenolic compounds were preliminarily identified, including phlorotannins, phenolic acids, and flavonoids. Significant differences in content and variety of polyphenolics were found in evaluated brown macroalgae, which could be related to differences in antioxidant activity in vivo and in vitro. Moreover, the antioxidant activity might be related to the total phenolic content and the types of polyphenolics, especially phlorotannins. The findings presented in this study indicate that A. nodosum could be used as an important substitute for functional ingredients in foods and pharmaceutical preparations, as well as a raw material for phlorotannins research.

Planctomonas psychrotolerans sp. nov., isolated from rhizosphere soil of Suaeda salsa.

A psychrotolerant actinobacterium, designated strain J5903T, was isolated from an alkaline soil sample from the rhizosphere of Suaeda salsa collected in desertification land surrounding Jiuliancheng Nur in Hebei Province, PR China. Cells of the isolate were Gram-stain-positive, aerobic, non-motile and non-spore-forming cocci. Strain J5903T grew optimally at 20‒25 °C, at pH 7.0‒7.5 and with <1 % (w/v) NaCl. The cell-wall peptidoglycan type was B2γ with d-2,4-diaminobutyric acid and l-2,4-diaminobutyric acid as diagnostic amino acids. The muramyl residue was acetyl type. The menaquinones were MK-11, MK-12, MK-10 and MK-13. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and one unidentified glycolipid. The major whole-cell fatty acids were anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. The genomic DNA G+C content was 69.1 mol%. It shared the highest average nucleotide identity and digital DNA-DNA hybridization values with Planctomonas deserti 13S1-3T. Phylogenies based on genome sequence showed that strain J5903T and P. deserti 13S1-3T formed a robust cluster with high bootstrap support. Strain J5903T shared typical chemotaxonomic characteristics with P. deserti 13S1-3T. Combining the polyphasic taxonomic evidence, strain J5903T represents a novel species of the genus Planctomonas, for which the name Planctomonas psychrotolerans sp. nov. is proposed. The type strain is J5903T (=DSM 101894T=CGMCC 1.15523T).

Phytoactinopolyspora mesophila sp. nov., isolated from a saline-alkaline soil.

A novel moderately halophilic, filamentous actinobacterium, designated as XMNu-373T, was isolated from a saline-alkaline soil sample collected from the Mongolia Plateau, Dongwu County, Inner Mongolia Autonomous Region, PR China. The isolate grew optimally at 28‒37 °C, pH 7.0‒8.0 and with 2-5 % (w/v) NaCl. The substrate mycelia fragmented into rod-like elements, and the white aerial mycelia formed spore chains at maturity. The predominant menaquinone was MK-9(H4). The polar lipids were diphosphatidylglycerol, three unidentified phosphoglycolipids, an unidentified aminophospholipid, two phosphatidylinositol mannosides, four unidentified phospholipids, phosphatidylglycerol and two unidentified lipids. The major cellular fatty acids were iso-C16 : 0, anteiso-C17 : 0 and anteiso-C15 : 0. The genomic DNA G+C content was 66.2 mol%. It shared high 16S rRNA gene sequence similarities to Phytoactinopolyspora halotolerans YIM 96448T (96.1 %) and Phytoactinopolyspora endophytica EGI 60009T (96.0 %). Phylogenetic trees based on 16S rRNA gene sequences revealed that strain XMNu-373T resided in the clade of family Jiangellaceae, and it formed a monophyletic branch distinct from four other recognized type species in the subclade of the genus Phytoactinopolyspora. On the basis of polyphasic taxonomic evidence, strain XMNu-373T represents a novel species of the genus Phytoactinopolyspora, for which the name Phytoactinopolyspora mesophila sp. nov. is proposed. The type strain is XMNu-373T (=JCM 33740T=CGMCC 4.7654T).

Auraticoccus cholistanensis sp. nov., an actinomycete isolated from soil of the Cholistan Desert, and emended description of the genus Auraticoccus.

A Gram-stain-positive, aerobic, non-motile and non-spore-forming actinobacterium, designated as F435T, was isolated from soil sample collected from the Cholistan Desert, Pakistan. The taxonomic position of the strain was established by using a polyphasic taxonomic approach. The cells were coccoid-shaped and found in single or arrangement of pairs. The novel strain grew at 15‒37 °C (optimum, 25‒30 °C), pH 7‒11 (optimum, pH 7-8) and in the presence of 0‒8% (w/v) NaCl (optimum, 0 %). Results of blast analysis based on 16S rRNA gene sequences showed that Auraticoccus monumenti MON 2.2T was its closest relative with 97.4 % similarity followed by Desertihabitans aurantiacus CPCC 204711T (95.2 %). In phylogenetic trees, strain F435T formed a robust cluster with the only member of the genus Auraticoccus. The peptidoglycan isomer present in the cell wall was ll-diaminopimelic acid. The major fatty acid was determined to be anteiso-C15 : 0. Characteristic polar lipids of the strain were diphosphatidylglycerol, phosphatidylglycerol, phosphoglycolipids and glycolipids. The predominant menaquinone was MK-9(H4). The genomic G+C content was calculated as 73.5 mol%. The digital DNA-DNA hybridization (GGDC) and average nucleotide identity (ANI) values between strain F435T and A. monumenti MON 2.2T were 24.6 and 81.8 %, respectively. Based on the results of phenotypic, chemotaxonomic, phylogenetic and phylogenomic analyses, strain F435T represents a novel specie of the genus Auraticoccus, for which the name Auraticoccus cholistanensis sp. nov. is proposed. The type strain is F435T (=JCM 33648T=CGMCC 1.17443T). The description of the genus Auraticoccus has also been emended.

Nocardioides vastitatis sp. nov., isolated from Taklamakan desert soil.

A Gram-stain-positive, aerobic, non-motile, rod-shaped actinobacterium, designated strain 21Sc5-5T, was isolated from a soil sample collected in the Taklamakan desert in Xinjiang Uygur Autonomous Region, PR China and investigated by using a polyphasic approach. Strain 21Sc5-5T grew at 10-37 °C (optimum, 28-30 °C), pH 6.0-9.0 (optimum, pH 7.0) and in the presence of 0-3 % (w/v) NaCl (optimum, 0 %). Phylogenetic analysis based on 16S rRNA gene sequences suggested that strain 21Sc5-5T formed a distinct lineage within the genus Nocardioides and had the highest similarity to Nocardioides albidus THG-S11.7T (97.30 %), followed by Nocardioides kongjuensis A2-4T (97.22 %), Nocardioides nitrophenolicus NSP 41T (97.15 %) and Nocardioides caeni MN8T (97.15 %). The results of chemotaxonomic analyses showed that the isolate possessed ll-diaminopimelic acid as the diagnostic diamino acid of the peptidoglycan and MK-8(H4) as the predominant menaquinone. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, an unidentified phospholipid and three unidentified lipids. The major fatty acids were iso-C16 : 0 and 10-methyl C18 : 0. The genome length of strain 21Sc5-5T was 4.67 Mb containing 372 contigs and with a DNA G+C content of 70.4 mol%. On the basis of data from phylogenetic, phenotypic and chemotaxonomic analyses, strain 21Sc5-5T represents a novel species of the genus Nocardioides, for which the name Nocardioides vastitatis sp. nov. is proposed. The type strain is 21Sc5-5T (=JCM 33365T=CGMCC 4.7608T).

Glycomyces buryatensis sp. nov., an actinobacterium isolated from steppe soil.

A novel actinobacterial strain, designated 18T, was isolated from a steppe soil sample collected in Buryatia, Russia and subjected to polyphasic taxonomic characterization. The strain was aerobic and Gram-stain-positive. The 16S rRNA gene sequence of strain 18T exhibited highest similarity to Glycomyces paridis CPCC 204357T (97.2 %). Results of phylogenetic analysis showed that strain 18T formed a distinct branch clearly affiliated to the genus Glycomyces. Whole-cell hydrolysates of the isolate contained meso-diaminopimelic acid as the cell-wall diamino acid. The whole-cell sugar profile was found to contain galactose, glucose, ribose and xylose. MK-10(H4) and MK-11(H4) were the predominant menaquinones. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, five unidentified phospholipids and four unidentified polar lipids. The major fatty acids identified were anteiso-C15 : 0 and iso-C15 : 0. The G+C content of the genomic DNA of strain 18T was 68.0 mol% (draft genome sequence). Based on its phylogenetic, phenotypic and chemotaxonomic features, strain 18T was considered to represent a novel species of the genus Glycomyces, for which the name Glycomyces buryatensis sp. nov. is proposed. The type strain of Glycomyces buryatensis is 18T (=JCM 33362T=CGMCC 4.7610T).

Desertihabitans brevis sp. nov., an actinobacterium isolated from sand of the Taklamakan desert, and emended description of the genus Desertihabitans.

A novel actinobacterium, designated strain 16Sb5-5T, was isolated from a sand sample collected in the Taklamakan desert in Xinjiang Uygur Autonomous Region, China. The strain was examined by a polyphasic approach to clarify its taxonomic position. Cells of the isolate were Gram-staining-positive, aerobic, non-motile and short-rod shaped. Strain 16Sb5-5T grew optimally at 37 °C, pH 7.0 and with 0‒2 % (w/v) NaCl. The cell-wall peptidoglycan was of the A3γ type and contained alanine, glycine, glutamic acid and ll-diaminopimelic acid (ll-DAP). Ribose, arabinose and glucose were detected in the whole-cell hydrolysates. The predominant menaquinone was MK-9(H4). The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, an unidentified phospholipid, three unidentified glycolipids and three unidentified lipids. The major whole-cell fatty acids were anteiso-C15 : 0 and iso-C15 : 0. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 16Sb5-5T was closely related to Desertihabitans aurantiacus CPCC 204711T (99.8 % similarity) and formed a robust clade with D. aurantiacus in the phylogenetic trees. In silico genomic comparisons showed that strain 16Sb5-5T exhibited ANI values of 94.8-94.9 % and GGDC value of 59.5 % to D. aurantiacus CPCC 204711T. The genomic G+C content was 73.3 mol%. On the basis of phylogenetic, phenotypic and chemotaxonomic analyses, strain 16Sb5-5T could be distinguishable from its closest phylogenetic relative and represents a novel species of the genus Desertihabitans, for which the name Desertihabitans brevis sp. nov. is proposed. The type strain is 16Sb5-5T (=KCTC 49116T=CGMCC 1.16553T). The description of the genus Desertihabitans has also been emended.

Labedella phragmitis sp. nov. and Labedella populi sp. nov., two endophytic actinobacteria isolated from plants in the Taklamakan Desert and emended description of the genus Labedella.

Two novel strains, designated 11W25H-1T and 8H24J-4-2T, were isolated from surface-sterilized plant tissues collected from the Taklamakan Desert in the Xinjiang Uygur Autonomous Region, China. The strains were characterized by a polyphasic approach in order to clarify their taxonomic positions. They were Gram-stain positive, aerobic, non-motile, non-spore-forming and rod-shaped. The 16S rRNA gene sequences of the strains showed highest similarities with Labedella gwakjiensis KCTC 19176T (99.2% and 98.9%, respectively) and Labedella endophytica CPCC 203961T (98.9% and 99.0%, respectively). The sequence similarity between strains 11W25H-1T and 8H24J-4-2T was 99.4%. Phylogenetic analyses based on 16S rRNA gene sequences and single-copy phylogenetic marker genes (pMGs) showed that the two strains belonged to the genus Labedella and formed a separate cluster from the closest species L. gwakjiensis KCTC 19176T and L. endophytica CPCC 203961T. Genomic analyses, including average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH), clearly separated the strains from each other and from the other species of the genus Labedella with values below the thresholds for species delineation. The two strains showed chemotaxonomic characteristics and phenotypic properties in agreement with the description of the genus Labedella and also confirmed the differentiation from the closest species. The data demonstrated that strains 11W25H-1T and 8H24J-4-2T represented two novel species of the genus Labedella, for which the names Labedella phragmitis sp. nov. (type strain 11W25H-1T=JCM 33144T=CGMCC 1.16700T) and Labedella populi sp. nov. (type strain 8H24J-4-2T=JCM 33143T=CGMCC 1.16697T) are proposed.

Kocuria soli sp. nov., an actinobacterium isolated from soil.

A Gram-stain-positive, aerobic, coccoid-shaped, non-spore-forming actinobacterial strain, designated M5W7-7T, was isolated from a hot spring soil sample collected from Anshan, Liaoning province, PR China. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain M5W7-7T clustered closely with species of the genus Kocuria, and showed the highest sequence similarity of 97.1 % to Kocuria subflava YIM 13062T. Strain M5W7-7T grew at 10-37 °C (optimum, 37 °C), pH6.0-11.0 (pH 6.0-7.0) and in the presence of 0-7 % (w/v) NaCl (0 %). Substrate mycelia and aerial mycelia were not formed, and diffusible pigments were not observed on any media tested. Strain M5W7-7T contained MK-6(H2) and MK-7(H2) as the dominant menaquinones. The polar lipid profile of strain M5W7-7T contained diphosphatidylglycerol, phosphatidylglycerol, two unidentified glycolipids, an unidentified phospholipid and an unidentified lipid. The predominant whole-cell sugars were galactose and glucose. The predominant fatty acid was anteiso-C15 : 0. The DNA G+C content of strain M5W7-7T was 67.0 mol%. On the basis of phylogenetic relationships, phenotypic characterization and chemotaxonomic analyses, strain M5W7-7T represents a novel species of the genus Kocuria, for which the name Kocuriasoli sp. nov. is proposed. The type strain is M5W7-7T (=KCTC 49195T =CGMCC 1.13744T).

Planctomonas deserti gen. nov., sp. nov., a new member of the family Microbacteriaceae isolated from soil of the Taklamakan desert.

A Gram-staining-positive, aerobic, irregular coccoid- to ovoid-shaped, non-spore-forming and motile bacterium, designated strain 13S1-3T, was isolated from a soil sample from the rhizosphere of Tamarix collected in the Taklamakan desert in Xinjiang Uygur Autonomous Region, PR China. The strain was examined by a polyphasic approach to clarify its taxonomic position. Strain 13S1-3T grew optimally at 28-30 °C, pH 7.0 and with 0-1 % (w/v) NaCl. The cell-wall peptidoglycan was of the B2γ type and contained d-alanine, d-glutamic acid, glycine, d-2,4-diaminobutyric acid and l-2,4-diaminobutyric acid. Ribose, xylose, glucose and galactose were detected as cell-wall sugars. The acyl type of the muramic acid was acetyl. The predominant menaquinones were MK-12, MK-11, MK-13 and MK-10. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, two unidentified glycolipids and one unidentified phospholipid. The major whole-cell fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The DNA G+C content was 70.4 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that 13S1-3T represented a member of the family Microbacteriaceae and showed the highest level of 16S rRNA gene sequence similarity with Frondihabitans australicus E1HC-02T (97.11 %). Phylogenetic trees revealed that 13S1-3T formed a distinct lineage with respect to closely related genera within the family Microbacteriaceae. On the basis of the results of phylogenetic, phenotypic and chemotaxonomic analyses, 13S1-3T is distinguishable from phylogenetically related genera in the family Microbacteriaceae, and represents a novel species of a new genus, for which the name Planctomonas deserti gen. nov., sp. nov. is proposed. The type strain is 13S1-3T (=KCTC 49115T=CGMCC 1.16554T).

Amnibacterium flavum sp. nov., a novel endophytic actinobacterium isolated from bark of Nerium indicum Mill.

A Gram-stain-positive, aerobic, short-rod-shaped, non-spore-forming actinobacterial strain, designated M8JJ-5T, was isolated from a surface-sterilized bark of Neriumindicum Mill. collected from Guizhou, China, and investigated by a polyphasic approach to determine its taxonomic position. Strain M8JJ-5T grew optimally without NaCl at 28 °C and at pH 7.0-8.0. Substrate mycelia and aerial mycelia were not formed, and no diffusible pigments were observed on the media tested. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain M8JJ-5T was most closely related to the type strains of genus Amnibacterium, and shared highest 16S rRNA gene sequence similarity of 97.29 % to Amnibacterium kyonggiense KSL51201-037T. The DNA G+C content of strain M8JJ-5T was 68.6 mol%. The cell-wall peptidoglycan contained l-2,4-diaminobutyric acid and MK-12, MK-11 were the major menaquinones. The predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol, an unidentified glycolipid, an unidentified phospholipid and an unidentified lipid, while the major fatty acids were iso-C16 : 0, anteiso-C15 : 0 and anteiso-C17 : 0. On the basis of phylogenetic, chemotaxonomic and phenotypic data, strain M8JJ-5T can be characterized to represent a novel species of the genus Amnibacterium, for which the name Amnibacteriumflavum sp. nov. is proposed. The type strain is M8JJ-5T (=KCTC 49089T=CGMCC 1.16390T).

Brachybacterium endophyticum sp. nov., a novel endophytic actinobacterium isolated from bark of Scutellaria baicalensis Georgi.

A Gram-positive, aerobic, coccus-shaped, non-spore-forming actinobacterium, designated strain M1HQ-2T, was isolated from a surface-sterilized bark of Scutellaria baicalensis Georgi collected from Guizhou, China and tested using a polyphasic approach to determine its taxonomic position. Strain M1HQ-2T grew at 4-37 °C (optimum, 30 °C), pH 5.0-11.0 (pH 8.0) and in the presence of 0-15 % (w/v) NaCl (1-3 %). Substrate mycelia and aerial mycelia were not formed, and diffusible pigments were not observed on any media tested. Phylogenetic analysis based on 16S rRNA gene sequence indicated that strain M1HQ-2T belonged to the genus Brachybacterium and had the highest 16S rRNA gene sequence similarity of 97.6 % to Brachybacteriumsquillarum M-6-3T. Strain M1HQ-2T contained MK-7 as the dominant menaquinone. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The polar lipids profile of strain M1HQ-2T contained diphosphatidylglycerol, phosphatidylglycerol, an unidentified phospholipid and an unidentified lipid. The predominant fatty acids were anteiso-C15 : 0 and anteiso-C17 : 0. The DNA G+C content of strain M1HQ-2T was 71.0 mol%. The average nucleotide identity value between strain M1HQ-2T and type strain of Brachybacterium sacelli was 76.7 %. The estimated DNA-DNA hybridization value between strain M1HQ-2T and type strain of B. sacelli was 20.6 %. On the basis of phylogenetic analysis, chemotaxonomic characteristics and phenotypic data, strain M1HQ-2T represents a novel species of the genus Brachybacterium, for which the name Brachybacteriumendophyticum sp. nov. is proposed. The type strain is M1HQ-2T (=KCTC 49087T=CGMCC 1.16391T).

Mangrovicella endophytica gen. nov., sp. nov., a new member of the family Aurantimonadaceae isolated from Aegiceras corniculatum.

A Gram-negative, aerobic, motile and short-rod-shaped bacterium, designated strain 5T4P-12-1T, was isolated from a piece of surface-sterilized bark of Aegiceras corniculatum collected from Cotai Ecological Zones in Macao, China and tested by a polyphasic approach to clarify its taxonomic position. Strain 5T4P-12-1T grew optimally with 0-1 % (w/v) NaCl at 30 °C and at pH 7.0-8.0. The 16S rRNA gene sequence of strain 5T4P-12-1T had the highest similarity (96.7 %) to Aureimonas altamirensis DSM 21988T. Phylogenic analysis based on 16S rRNA gene sequences and coding sequences of 98 protein clusters showed that the strain represented a novel genus of the family Aurantimonadaceae. The predominant quinone system of strain 5T4P-12-1T was ubiquinone 10. The polar lipid profile contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylmethylethanolamine, an unidentified aminophospholipid, three unidentified aminolipids, three unidentified phospholipids and three unidentified lipids. The major fatty acids (>10 % of total fatty acids) were C18 : 1ω7c (55.4 %) and C18 : 1 2-OH (15.6 %). The DNA G+C content of strain 5T4P-12-1T was 66.5 mol%. Based on the phylogenic, phenotypic and chemotaxonomic features, strain 5T4P-12-1T is considered to represent a novel species of a new genus in the family Aurantimonadaceae, for which the name Mangrovicella endophytica gen. nov., sp. nov. is proposed. The type strain is 5T4P-12-1T (=KCTC 62053T=CGMCC 1.16279 T).

Lower endogenous p53 levels and degradation of AKT protein contribute to potent suppression of the new antibiotic Xiakemycin A on tumor cells.

Xiakemycin A (XKA), a new pyranonaphthoquinone antibiotic, is isolated from the fermentation broth of Streptomyces sp. CC8-201. It exerts potent suppression of cell proliferation on some types of tumor cells. In the present study, its underlying mechanism on tumor cells has been investigated. In contrast to the specific AKT inhibitor triciribine hydrate, XKA demonstrated a weak inhibition of the AKT kinase activity in vitro. Knockdown of AKT protein levels reduced XKA-inhibitory action on prostate carcinoma PC-3 cells. Degradation of AKT protein was markedly observed in the XKA-treated PC-3 cells in comparison with triciribine hydrate treatment. There was no typical apoptosis induced by XKA in PC-3 cells. The propidium iodide-stained cells increased concentration-dependently when the cells were treated with XKA. Degradation of apoptosis-related proteins, such as p53 and PARP-1, was also detected in the XKA-treated PC-3 cells. Knockdown of p53 protein levels potentiated XKA action on non-small lung cancer A549 cells. Collectively, the mechanism of XKA potent inhibition was due to degradation of AKT protein and low endogenous p53 levels. As a leading compound, new derivatives based on XKA will be developed to precisely treat tumor cells which have high AKT and low p53 protein levels.

Marmoricola endophyticus sp. nov., an endophytic actinobacterium isolated from Thespesia populnea.

A novel endophytic actinobacterium, designated strain 8BXZ-J1T, was isolated from surface-sterilized branches of Thespesia populnea collected from Beilun Estuary Mangrove Forest National Nature Reserve in Guangxi, China, and examined by a polyphasic approach to determine its taxonomic position. Cells of the isolate were Gram-stain-positive, aerobic, non-spore-forming, non-motile and short rod-shaped. Phylogenetic analysis based on 16S rRNA gene sequences suggested that strain 8BXZ-J1T belonged to the genus Marmoricola, sharing highest similarity with Marmoricola solisilvae DSM 27140T (96.9 %). The isolate grew at 10-35 °C (optimum, 28-30 °C), at pH 6.0-8.0 (optimum, pH 7.0) and in the presence of 0-10 % (w/v) NaCl (optimum, 0-5.0 %). The organism contained ll-2,6-diaminopimelic acid as the diagnostic diamino acid of the peptidoglycan, MK-8(H4) as the major menaquinone, and a polar lipid profile including diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylinositol and two unknown lipids. The major fatty acids of strain 8BXZ-J1T were C18 : 0 10-methyl, iso-C16 : 0 and C16 : 0. The G+C content of the genomic DNA was 68.7 mol%. These data demonstrate that strain 8BXZ-J1T is representative of a novel species of the genus Marmoricola, for which the name Marmoricola endophyticus sp. nov. is proposed. The type strain is 8BXZ-J1T (=KCTC 39789T=CGMCC 1.16067T).