Haloechinothrix alba gen. nov., sp. nov., a halophilic, filamentous actinomycete of the suborder Pseudonocardineae

Pretty in pink? Complementary strategies for analysing pink biofilms on historical buildings

Salt-weathering is a deterioration mechanism affecting building materials that results from repetitive cycles of salt crystallisation-dissolution in the porous mineral network under changing environmental conditions, causing damage to surfaces. However, an additional biodeterioration phenomenon frequently associated with salt efflorescence is the appearance of coloured biofilms, comprising halotolerant/halophilic microorganisms, containing carotenoid pigments that cause pinkish patinas. In this work, two Austrian historical salt-weathered buildings showing pink biofilms, the St. Virgil's Chapel and the Charterhouse Mauerbach, were investigated. Substrate chemistry (salt concentration/composition) was analysed by ion chromatography and X-ray diffraction to correlate these parameters with the associated microorganisms. Microbiomes were analysed by sequencing full-length 16S rRNA amplicons using Nanopore technology. Data demonstrates that microbiomes are not only influenced by salt concentration, but also by its chemical composition. The chapel showed a high overall halite (NaCl) concentration, but the factor influencing the microbiome was the presence/absence of K+. The K+ areas showed a dominance of Aliifodinibius and Salinisphaera species, capable of tolerating high salt concentrations through the "salt-in" strategy by transporting K+ into cells. Conversely, areas without K+ showed a community shift towards Halomonas species, which favour the synthesis of compatible solutes for salt tolerance. In the charterhouse, the main salts were sulphates. In areas with low concentrations, Rubrobacter species dominated, while in areas with high concentrations, Haloechinothrix species did. Among archaea, Haloccoccus species were dominant in all samples, except at high sulphate concentrations, where Halalkalicoccus prevailed. Finally, the biological pigments visible in both buildings were analysed by Raman spectroscopy, showing the same spectra in all areas investigated, regardless of the building and the microbiomes, demonstrating the presence of carotenoids in the pink biofilms. Comprehensive information on the factors affecting the microbiome associated with salt-weathered buildings should provide the basis for selecting the most appropriate desalination treatment to remove both salt efflorescence and associated biofilms.

Pseudomonas subflava sp. nov., a new Gram-negative bacterium isolated from Guishan in Yunnan province, south-west China

A new Gram-negative, rod-shaped, flagellated bacterium was isolated from soil in the Guishan, Xinping County, Yuxi City, Yunnan Province, China, and named YIM B01952^T. Growth occurred at 10-40 °C (optimum, 30 °C), pH 6.0-9.0 (optimum, pH 7.5) and with up to ≤ 5.0% (w/v) NaCl on Tryptic Soy Broth Agar (TSA) plates. Phylogenetic analysis based on the 16S rRNA gene and draft-genome sequence showed that strain YIM B01952^T belonged to the genus Pseudomonas, and was closely related to the type strain of Pseudomonas alcaligenes (sequence similarity was 98.8%). The digital DNA-DNA hybridization (dDDH) value between strain YIM B01952^T and the parallel strain P. alcaligenes ATCC 14909^T was 49.0% based on the draft genome sequence. The predominant menaquinone was Q-9. The major fatty acids were summed feature 8 (C_18:1 ω6c and/or C_18:1 ω7c), summed feature 3 (C_16:1 ω6c and/or C_16:1 ω7c) and C_16:0. The major polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, and phosphatidylglycerol. The genome size of strain YIM B01952^T was 4.341 Mb, comprising 4156 predicted genes with a DNA G + C content of 66.4 mol%. In addition, we detected that strain YIM B01952^T had some traditional functional genes (plant growth promotion and multidrug resistance), unique genes through genome comparison and analysis with similar strains. Based on genetic analyses and biochemical characterization, the strain YIM B01952^T was identified as a novel species in the genus Pseudomonas, for which the name Pseudomonas subflava sp. nov. is proposed. The type strain is YIM B01952^T (=CCTCC AB 2021498^T = KCTC 92073^T).

Viridibacillus soli sp. nov., isolated from forest soil in Ailaoshan National Nature Reserve

A Gram stain-positive, rod-shaped, and subterminal endospore-forming bacterium, designated strain YIM B01967^T, was isolated from a forest soil sample collected in Ailaoshan National Nature Reserve, Yuxi City, Xinpin county, Yunnan province, China. Strain YIM B01967^T showed the highest 16S rRNA gene sequence similarity with Viridibacillus arvi (99.1%) and Viridibacillus arenosi (98.9%). Based on the phylogenetic and 16S rRNA gene sequence results, strain YIM B01967^T was affiliated to the genus Viridibacillus. The growth of YIM B01967^T was observed at 15-35 °C (optimum, 28 °C), pH 7.0-9.0 (optimum, pH 7.5) and in the presence of 0-2% (w/v) NaCl (optimum in 2% NaCl). The cell wall sugars include ribose, glucose, arabinose, galactose, and mannose. The quinone system consisted of the major compound MK-8 and moderate amounts of MK-7. The major fatty acids (> 10%) included iso-C_15:0, anteiso-C_15:0, C_16:1 ω10c. The major polar lipids profile included DPG, PME. The cell wall peptidoglycan was most likely of the type A4α with an L-Lys-D-Asp interpeptide bridge. The genomic DNA G + C content of strain YIM B01967^T was 36.3 mol%. The ANI and digital DNA-DNA hybridization (dDDH) values between strain YIM B01967^T and Viridibacillus arvi DSM 16317 ^T, Viridibacillus arenosi DSM 16319 ^T were 61.0% and 32.1%, 60.0% and 33.1% based on the draft genome sequence. The results support the conclusion that strain YIM B01967^T represents a novel species of the genus Viridibacillus, for which the name Viridibacillus soli sp. nov., is proposed. The type strain is YIM B01967^T (= KCTC 43249 ^T = CGMCC 1.18436 ^T).

Qaidamihabitans albus gen. nov., sp. nov., a new member of the family Pseudonocardiaceae, and transfer of Prauserella shujinwangii to Qaidamihabitans gen. nov. as Qaidamihabitans shujinwangii comb. nov

A novel mycelium-forming actinomycete strain, designated YIM S01255^T were isolated from a salt lake. Optimal growth occurred in the presence of 0-5.0% (w/v) NaCl, at pH 7.0-8.0, and at 37 °C. Strain YIM S01255^T contained meso-diaminopimelic acid as the diagnostic diamino acid, and glucose, galactose and arabinose as the whole-cell sugars. The major fatty acid (> 5.0%) were iso-C_16:0, iso-C_16:1H and iso-C_15:0. The major menaquinone were MK-9(H₄) and MK-8(H₄). The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylinositolmannoside and phosphatidylinositol. The DNA G + C content was 70.7 mol%. The 16S rRNA gene sequence of the strain showed high similarity to members of genera in the family Pseudonocardiaceae with values less than 95.8%, and most closely related to the genus Amycolatopsis. Both of phylogenetic analysis based on 16S rRNA gene sequences and the up-to-date bacterial genome sequences analysis revealed that strains YIM S01255^T and Prauserella shujinwangii XJ46^T formed a distinct monophyletic clade and was separated from the other members within the family Pseudonocardiaceae. The average nucleotide identity (ANI) values and digital DNA-DNA hybridization (dDDH) between the two strains were 81.0% and 40.6%, respectively. The distinctive polyphasic evidences differentiated YIM S01255^T from members of the family Pseudonocardiaceae, so strain YIM S01255^T is considered to represent a novel species of a novel genus of the family Pseudonocardiaceae, for which the name Qaidamihabitans albus gen. nov., sp. nov. is proposed. The type strain of genus Qaidamihabitans is YIM S01255^T (= KCTC 49476^T = CGMCC 4.7684^T). Moreover, Prauserella shujinwangii is also proposed to being transferred into the genus Qaidamihabitans as Qaidamihabitans shujinwangii comb. nov. (type strain XJ46^T = CGMCC 4.7125^T = JCM 19736^T).

From ecophysiology to cultivation methodology: filling the knowledge gap between uncultured and cultured microbes

Earth is dominated by a myriad of microbial communities, but the majority fails to grow under in situ laboratory conditions. The basic cause of unculturability is that bacteria dominantly occur as biofilms in natural environments. Earlier improvements in the culture techniques are mostly done by optimizing media components. However, with technological advancement particularly in the field of genome sequencing and cell imagining techniques, new tools have become available to understand the ecophysiology of microbial communities. Hence, it becomes easier to mimic environmental conditions in the culture plate. Other methods include co-culturing, emendation of growth factors, and cultivation after physical cell sorting. Most recently, techniques have been proposed for bacterial cultivation by employing genomic data to understand either microbial interactions (network-directed targeted bacterial isolation) or ecosystem engineering (reverse genomics). Hopefully, these techniques may be applied to almost all environmental samples, and help fill the gaps between the cultured and uncultured microbial communities.

Aestuariimicrobium ganziense sp. nov., a new Gram-positive bacterium isolated from soil in the Ganzi Tibetan autonomous prefecture, China

A novel Gram-stain positive, oval-shaped, and non-flagellated bacterium, designated YIM S02566^T, was isolated from alpine soil in Shadui Towns, Ganzi County, Ganzi Tibetan Autonomous Prefecture, Sichuan Province, PR China. Growth occurred at 23-35 °C (optimum, 30 °C) in the presence of 0.5-4% (w/v) NaCl (optimum, 1%) and at pH 7.0-8.0 (optimum, pH 7.0). The phylogenetic analysis based on 16S rRNA gene sequence revealed that strain YIM S02566^T was most closely related to the genus Aestuariimicrobium, with Aestuariimicrobium kwangyangense R27^T and Aestuariimicrobium soli D6^T as its closest relative (sequence similarities were 96.3% and 95.4%, respectively). YIM S02566^T contained LL-diaminopimelic acid in the cell wall. MK-9(H4) was the predominant menaquinone. The major fatty acid patterns were anteiso-C_15:0 (60.0%). The major polar lipid was DPG. The genome size of strain YIM S02566^T was 3.1 Mb, comprising 3078 predicted genes with a DNA G + C content of 69.0 mol%. Based on these genotypic, chemotaxonomic and phenotypic evidences, strain YIM S02566^T was identified as a novel species in the genus Aestuariimicrobium, for which the name Aestuariimicrobium ganziense sp. nov. is proposed. The type strain is YIM S02566^T (= CGMCC 1.18751 T = KCTC 49,477 T).

Paenibacillus turpanensis sp. nov., isolated from a salt lake of Turpan city in Xinjiang province, north-west China

Strain YIM B00363^T, a Gram-positive, aerobic, non-motile, rod-shaped, spore-forming bacterium, was isolated from saline soil samples collected from a salt lake in Xinjiang province, north-west China, and was characterized using a polyphasic approach. The optimum growth temperature was 37 °C and the optimum pH was 7.5-8.0. The major menaquinone was MK-7; anteiso-C_15:0 (53.52%), iso-C_15:0 (15.04%) and C_16:0 (12.76%) were the predominant cellular fatty acids. The diagnostic diamino acid of the cell wall peptidoglycan was meso-diaminopimelic acid. The phospholipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, unidentified phospholipids, unidentified glycolipids and unknown lipids. The DNA G + C content of the type strain was 50.4 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain YIM B00363^T belonged to a cluster comprising species of the genus Paenibacillus. The nearest relatives were P. residui MC-246^T and P. senegalensis JC66^T, with 93.2% and 92.8% gene sequence similarities, respectively. On the basis of its phenotypic characteristics and phylogenetic distinctivenes, strain YIM B00363^T represents a novel species of the genus Paenibacillus, for which the name Paenibacillus turpanensis sp. nov. is proposed. The type strain is YIM B00363^T (= CGMCC 1.17507^T = KCTC 43184^T).

Revisiting the Taxonomic Status of the Biomedically and Industrially Important Genus Amycolatopsis, Using a Phylogenomic Approach

Strains belonging to the genus Amycolatopsis are well known for the production of a number of important antimicrobials and other bioactive molecules. In this study, we have sequenced the genomes of five Amycolatopsis strains including Amycolatopsis circi DSM 45561^T, Amycolatopsis palatopharyngis DSM 44832^T and Amycolatopsis thermalba NRRL B-24845^T. The genome sequences were analyzed with 52 other publically available Amycolatopsis genomes, representing 34 species, and 12 representatives from related genera including Saccharomonospora, Saccharopolyspora, Saccharothrix, Pseudonocardia and Thermobispora. Based on the core genome phylogeny, Amycolatopsis strains were subdivided into four major clades and several singletons. The genus Amycolatopsis is homogeneous with only three strains noted to group with other genera. Amycolatopsis halophila YIM93223^T is quite distinct from other Amycolatopsis strains, both phylogenetically and taxonomically, and belongs to a distinct genus. In addition, Amycolatopsis palatopharyngis DSM 44832^T and Amycolatopsis marina CGMCC4 3568^T grouped in a clade with Saccharomonospora strains and showed similar taxogenomic differences to this genus as well as other Amycolatopsis strains. The study found a number of strains, particularly those identified as Amycolatopsis orientalis, whose incorrect identification could be resolved by taxogenomic analyses. Similarly, some unclassified strains could be assigned with species designations. The genome sequences of some strains that were independently sequenced by different laboratories were almost identical (99-100% average nucleotide and amino acid identities) consistent with them being the same strain, and confirming the reproducibility and robustness of genomic data. These analyses further demonstrate that whole genome sequencing can reliably resolve intra- and, inter-generic structures and should be incorporated into prokaryotic systematics.

Genome-Based Taxonomic Classification of the Phylum Actinobacteria

The application of phylogenetic taxonomic procedures led to improvements in the classification of bacteria assigned to the phylum Actinobacteria but even so there remains a need to further clarify relationships within a taxon that encompasses organisms of agricultural, biotechnological, clinical, and ecological importance. Classification of the morphologically diverse bacteria belonging to this large phylum based on a limited number of features has proved to be difficult, not least when taxonomic decisions rested heavily on interpretation of poorly resolved 16S rRNA gene trees. Here, draft genome sequences of a large collection of actinobacterial type strains were used to infer phylogenetic trees from genome-scale data using principles drawn from phylogenetic systematics. The majority of taxa were found to be monophyletic but several orders, families, and genera, as well as many species and a few subspecies were shown to be in need of revision leading to proposals for the recognition of 2 orders, 10 families, and 17 genera, as well as the transfer of over 100 species to other genera. In addition, emended descriptions are given for many species mainly involving the addition of data on genome size and DNA G+C content, the former can be considered to be a valuable taxonomic marker in actinobacterial systematics. Many of the incongruities detected when the results of the present study were compared with existing classifications had been recognized from 16S rRNA gene trees though whole-genome phylogenies proved to be much better resolved. The few significant incongruities found between 16S/23S rRNA and whole genome trees underline the pitfalls inherent in phylogenies based upon single gene sequences. Similarly good congruence was found between the discontinuous distribution of phenotypic properties and taxa delineated in the phylogenetic trees though diverse non-monophyletic taxa appeared to be based on the use of plesiomorphic character states as diagnostic features.

Actinocrispum wychmicini gen. nov., sp. nov., a novel member of the family Pseudonocardiaceae, isolated from soil

A novel actinomycete, designated MI503-A4T, was isolated from soil. Comparative analysis of 16S rRNA gene sequences indicated that MI503-A4T was phylogenetically related to members of the family Pseudonocardiaceae. The most closely related genus was Kibdelosporangium (95.7-96.2 % sequence similarity). Substrate mycelia were branched and pale yellow to pale yellowish-brown. Straight- to zigzag-shaped aerial mycelia were observed, but Sporangium-like structures were absent. The whole-cell hydrolysate contained meso-diaminopimelic acid. The muramic acid residues in the peptidoglycan were N-acetylated. Whole-cell sugars were rhamnose, ribose, arabinose and galactose (cell wall chemotype IV). The predominant menaquinone was MK-9(H4). A small amount of MK-8(H4) was also detected. The DNA G+C content was 70.3-71.1 mol%. Polar lipids contained diphosphatidylglycerol, phosphatidylethanolamine and hydroxyl-phosphatidylethanolamine. Cellular fatty acid analysis of MI503-A4T detected predominantly iso-C14 : 0 (11.5 %), iso-C15 : 0 (13.3 %) and iso-C16 : 0 (35.7 %). Phenotypic and phylogenetic characteristics differentiated MI503-A4T from members of all genera within the family Pseudonocardiaceae with validly published names. Therefore, MI503-A4T is proposed to be a representative of a novel species in a novel genus, Actinocrispum wychmicini gen. nov., sp. nov. The type strain of the type species is MI503-A4T (=NBRC 109632T=DSM 45934T).

Tamaricihabitans halophyticus gen. nov., sp. nov., an endophytic actinomycete of the family Pseudonocardiaceae

A novel actinomycete strain, designated KLBMP 1356T, was isolated from the root of halophyte Tamarix chinensis Lour. collected from the coastal area of Jiangsu province, PR China. The isolate was characterized using a polyphasic approach. Comparative analysis of the 16S rRNA gene sequence indicated that strain KLBMP 1356T was phylogenetically related to members of the family Pseudonocardiaceae and formed a distinct monophyletic clade between the genera Amycolatopsis (93.1–94.7 % 16S rRNA gene sequence similarity), Prauserella (93.6–95.1 %) and Saccharomonospora (93.2–94.3 %). The isolate displayed long spore chains containing rod-shaped and smooth-surfaced spores. Strain KLBMP 1356T contained meso-diaminopimelic acid as the diagnostic diamino acid, and galactose, arabinose and glucose as the whole-cell sugars. The major menaquinone was MK-9(H4) and the fatty acid profile was characterized by the predominance of iso-C16 : 0, C17 : 1ω8c, C17 : 1ω6c and C17 : 0. The polar lipids comprised diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, unknown aminophospholipids and an unknown glycolipid. Mycolic acids were not present. The G+C content of the genomic DNA was 67.2 mol%. On the basis of the evidence from this polyphasic study, strain KLBMP 1356T is considered to represent a novel species of a new genus in the family Pseudonocardiaceae, for which the name Tamaricihabitans halophyticus gen. nov., sp. nov. is proposed. The type strain of the type species is KLBMP 1356T ( = DSM 45765T = NBRC 109361T).

Thermotunica guangxiensis gen. nov., sp. nov., isolated from mushroom residue compost

A novel thermophilic actinomycete, designated AG2-7T, was isolated from mushroom residue compost in Guangxi University, Nanning, China. The strain grew optimally at 45–60 °C, at pH 7.0 and with 0–3.0 % (w/v) NaCl. Vegetative mycelia were branched and whitish to pale yellow without fragmentation. Aerial mycelium was abundant, whitish and differentiated into long chains of spores, with a membranous structure or tunica partially covering the surface of aerial hyphae. The non-motile spores were oval in shape with a ridged surface. Strain AG-27T contained meso-diaminopimelic acid as the diagnostic diamino acid, and the whole-cell sugars were galactose and ribose. Major fatty acids were iso-C16 : 0 (27.51 %), iso-C17 : 0 (10.47 %) and anteiso-C17 : 0 (12.01 %). MK-9(H4) was the predominant menaquinone. The polar phospholipids were diphosphatidylglycerol, ninhydrin-positive glycophospholipid, phosphatidylinositol, phosphatidylinositol mannoside, phosphatidylethanolamine, phosphatidylmethylethanolamine, an unknown phospholipid and unknown glucosamine-containing phospholipids. The G+C content of the genomic DNA was 63.6 mol%. 16S rRNA gene sequence analysis showed that the organism belonged to the family Pseudonocardiaceae , suborder Pseudonocardineae and showed more than 5 % divergence from other members of the family. Based on the phenotypic and phylogenetic data, strain AG2-7T represents a novel species of a new genus in the family Pseudonocardiaceae , for which the name Thermotunica guangxiensis gen. nov., sp. nov. is proposed. The type strain of the type species is AG2-7T ( = ATCC BAA-2499T = CGMCC 4.7099T).

Longimycelium tulufanense gen. nov., sp. nov., a filamentous actinomycete of the family Pseudonocardiaceae

A novel filamentous actinomycete strain, designated TRM 46004T, was isolated from sediment of Aiding Lake in Tulufan Basin (42° 64′ N 89° 26′ E), north-west China. The isolate was characterized using a polyphasic approach. The isolate formed abundant aerial mycelium with few branches and vegetative mycelium, occasionally twisted and coiled; spherical sporangia containing one to several spherical spores developed at the ends of short sporangiophores on aerial mycelium. The G+C content of the DNA was 65.2 mol%. The isolate contained meso-diaminopimelic acid as the diagnostic diamino acid and xylose, galactose and ribose as the major whole-cell sugars. The diagnostic phospholipids were phosphatidylethanolamine, phosphatidylcholine and phosphatidylglycerol. The predominant menaquinones were MK-9(H4), MK-9(H6) and MK-9(H10). The major fatty acids were iso-C16 : 0 and anteiso-C17 : 0. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain TRM 46004T formed a distinct lineage within the family Pseudonocardiaceae and showed 91.7–96.1 % 16S rRNA gene sequence similarity with members of the family Pseudonocardiaceae . On the basis of the evidence from this polyphasic study, a novel genus and species, Longimycelium tulufanense gen. nov., sp. nov., are proposed. The type strain of Longimycelium tulufanense is TRM 46004T ( = CGMCC 4.5737T = NBRC 107726T).

Systematic and biotechnological aspects of halophilic and halotolerant actinomycetes

More than 70 species of halotolerant and halophilic actinomycetes belonging to at least 24 genera have been validly described. Halophilic actinomycetes are a less explored source of actinomycetes for discovery of novel bioactive secondary metabolites. Degradation of aliphatic and aromatic organic compounds, detoxification of pollutants, production of new enzymes and other metabolites such as antibiotics, compatible solutes and polymers are other potential industrial applications of halophilic and halotolerant actinomycetes. Especially new bioactive secondary metabolites that are derived from only a small fraction of the investigated halophilic actinomycetes, mainly from marine habitats, have revealed the huge capacity of this physiological group in production of new bioactive chemical entities. Combined high metabolic capacities of actinomycetes and unique features related to extremophilic nature of the halophilic actinomycetes have conferred on them an influential role for future biotechnological applications.

Reassessment of the systematics of the suborder Pseudonocardineae: transfer of the genera within the family Actinosynnemataceae Labeda and Kroppenstedt 2000 emend. Zhi et al. 2009 into an emended family Pseudonocardiaceae Embley et al. 1989 emend. Zhi et al. 2009

The taxonomic status of the families Actinosynnemataceae and Pseudonocardiaceae was assessed based on 16S rRNA gene sequence data available for the 151 taxa with validly published names, as well as chemotaxonomic and morphological properties available from the literature. 16S rRNA gene sequences for the type strains of all taxa within the suborder Pseudonocardineae were subjected to phylogenetic analyses using different algorithms in arb and phylip. The description of many new genera and species within the suborder Pseudonocardineae since the family Actinosynnemataceae was proposed in 2000 has resulted in a markedly different distribution of chemotaxonomic markers within the suborder from that observed at that time. For instance, it is noted that species of the genera Actinokineospora and Allokutzneria contain arabinose in whole-cell hydrolysates, which is not observed in the other genera within the Actinosynnemataceae, and that there are many genera within the family Pseudonocardiaceae as currently described that do not contain arabinose. Phylogenetic analyses of 16S rRNA gene sequences for all taxa within the suborder do not provide any statistical support for the family Actinosynnemataceae, nor are signature nucleotides found that support its continued differentiation from the family Pseudonocardiaceae. The description of the family Pseudonocardiaceae is therefore emended to include the genera previously classified within the family Actinosynnemataceae and the description of the suborder Pseudonocardineae is also emended to reflect this reclassification.