Genus Blastococcus Research Articles

Blastococcus brunescens sp. nov., a member of the Geodermatophilaceae isolated from sandstone collected from the Sahara Desert in Tunisia.

The taxonomic position of strain BMG 8361T, isolated from sandstone collected in the Sahara Desert of Southern Tunisia, was refined through a polyphasic taxonomic investigation. Colonies of BMG 8361T were pale-orange coloured, irregular with a dry surface and produced a diffusible pink or brown pigment depending on media. The Gram-positive cells were catalase-positive and oxidase-negative. The strain exhibited growth at 10-40 °C and pH values ranging from 5.5 to 9.0, with optima at 28-35 °C and pH 6.5-8.0. Additionally, BMG 8361T demonstrated the ability to grow in the presence of up to 1 % NaCl (w/v) concentration. The peptidoglycan of the cell wall contained meso-diaminopimelic acid, glucose, galactose, xylose, ribose, and rhamnose. The predominant menaquinones consisted of MK-9(H4) and MK-9. The main polar lipids were phosphatidylcholine, phosphatidylinositol, glycophosphatidylinositol, diphosphatidylglycerol, phosphatidylethanolamine, and two unidentified lipids. Major cellular fatty acids were iso-C16 : 0, iso-C16 : 1 h, and C17 : 1 ω8c. Phylogenetic analyses based on both the 16S rRNA gene and whole-genome sequences assigned strain BMG 8361T within the genus Blastococcus. The highest pairwise sequence similarity observed in the 16S rRNA gene was 99.5 % with Blastococcus haudaquaticus AT 7-14T. However, when considering digital DNA-DNA hybridization and average nucleotide identity, the highest values, 48.4 and 86.58 %, respectively, were obtained with Blastococcus colisei BMG 822T. These values significantly undershoot the recommended thresholds for establishing new species, corroborating the robust support for the distinctive taxonomic status of strain BMG 8361T within the genus Blastococcus. In conjunction with the phenotyping results, this compelling evidence leads to the proposal of a novel species we named Blastococcus brunescens sp. nov. with BMG 8361T (=DSM 46845T=CECT 8880T) as the type strain.

Genotype-phenotype correlations within the Geodermatophilaceae.

The integration of genomic information into microbial systematics along with physiological and chemotaxonomic parameters provides for a reliable classification of prokaryotes. In silico analysis of chemotaxonomic traits is now being introduced to replace characteristics traditionally determined in the laboratory with the dual goal of both increasing the speed of the description of taxa and the accuracy and consistency of taxonomic reports. Genomics has already successfully been applied in the taxonomic rearrangement of Geodermatophilaceae (Actinomycetota) but in the light of new genomic data the taxonomy of the family needs to be revisited. In conjunction with the taxonomic characterisation of four strains phylogenetically located within the family, we conducted a phylogenetic analysis of the whole proteomes of the sequenced type strains and established genotype-phenotype correlations for traits related to chemotaxonomy, cell morphology and metabolism. Results indicated that the four isolates under study represent four novel species within the genus Blastococcus. Additionally, the genera Blastococcus, Geodermatophilus and Modestobacter were shown to be paraphyletic. Consequently, the new genera Trujillonella, Pleomorpha and Goekera were proposed within the Geodermatophilaceae and Blastococcus endophyticus was reclassified as Trujillonella endophytica comb. nov., Geodermatophilus daqingensis as Pleomorpha daqingensis comb. nov. and Modestobacter deserti as Goekera deserti comb. nov. Accordingly, we also proposed emended descriptions of Blastococcus aggregatus, Blastococcus jejuensis, Blastococcus saxobsidens and Blastococcus xanthilyniticus. In silico chemotaxonomic results were overall consistent with wet-lab results. Even though in silico discriminatory levels varied depending on the respective chemotaxonomic trait, this approach is promising for effectively replacing and/or complementing chemotaxonomic analyses at taxonomic ranks above the species level. Finally, interesting but previously overlooked insights regarding morphology and ecology were revealed by the presence of a repertoire of genes related to flagellum synthesis, chemotaxis, spore production and pilus assembly in all representatives of the family. A rich carbon metabolism including four different CO2 fixation pathways and a battery of enzymes able to degrade complex carbohydrates were also identified in Blastococcus genomes.

Structural and functional responses of bacterial and fungal communities to multiple heavy metal exposure in arid loess

Concentration gradients of multiple heavy metals (HMs) in the arid loess region near a smelter were determined. In order to understand the response of soil microbes to multiple HM gradients, bacterial and fungal community structures and functions were analyzed using high-throughput RNA gene sequencing and the PICRUSt method. RDA/PCA analyses revealed that soil pH, HMs, and electrical conductivity (EC) jointly affected the bacterial communities in the soils. The soil microbial community structures responded differently to HMs, EC, and pH. High HMs increased the abundances of the bacterial phyla Actinobacteria, Bacteroidetes, Deinococcus-Thermus, and Chloroflexi, and the genera Blastococcus, Rubrobacter, Quadrisphaera, and Tunicatimonas, whereas they decreased the abundances of the phyla Proteobacteria and Acidobacteria and the genera Streptomyces and Nocardioides. High EC and low pH decreased the abundance of most of the dominant bacterial phyla but increased the abundances of Firmicutes, Deinococcus-Thermus, and Nitrospirae. Furthermore, high HMs and EC reduced the numbers of soil-specific bacterial and fungal groups and drove the succession of certain groups that were highly resistant to increased HMs and EC. In addition, many bacterial and fungal groups exhibited different response patterns to each HM, implying that, in multiple HM-contaminated soils, HMs jointly shaped the microbial communities. PICRUSt analysis suggested that high HMs significantly decreased the total gene abundance and most KEGG modules in the soils. High EC and low pH significantly enhanced the abundances of several two-component system-, electron transfer-, and methanogenesis-related modules. We conclude that excessive multiple HMs and EC principally repressed the microbial activity and severely drove the gradient succession of bacterial and fungal communities in the arid loess region.

Blastococcus deserti sp. nov., isolated from a desert sample.

A Gram-positive and aerobic actinobacterium, strain SYSU D8006T, was isolated from a desert sand sample collected from Gurbantunggut desert, China. Phenotypically, the strain was found to grow at 14-50°C, pH 6.0-9.0 and in the presence of up to 4% (w/v) NaCl. The chemotaxonomic features of strain SYSU D8006T included menaquinone MK-9(H4) as the respiratory quinone, diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside as known polar lipids, iso-C15:0, iso-C16:0, C17:1ω8c and C18:1ω9c as the predominant fatty acids, and arabinose, galactose and glucose as the whole cell sugars. Strain SYSU D8006T shared the highest 16S rRNA gene sequence identity with Blastococcus jejuensis DSM 19597T (98.2%). Based on the analyses of the phenotypic, genotypic and phylogenetic characteristics, strain SYSU D8006T is characterized to represent a novel species of the genus Blastococcus, for which the name Blastococcus deserti sp. nov. is proposed. The type strain is SYSU D8006T (= CGMCC 1.15935T = KCTC 49026T = CPCC 204618T).

Blastococcus litoris sp. nov., isolated from sea-tidal flat sediment.

A novel Gram-strain-positive, non-spore-forming bacterial strain, designated GP-S2-8T, was isolated from a sea-tidal flat sediment sample from Gopado, Republic of Korea. Cells were aerobic, catalase-negative, oxidase-positive, non-motile and cocci, occurring singly, in pairs or in tetrads, and often tending to form aggregates. The strain grew at 4-45 °C (optimum, 28-37 °C), at pH 4.0-11.0 (pH 7.0-9.0) and in the presence of 0-11 % (w/v) NaCl (0-3 %). Phylogenetic analyses based on 16S rRNA gene sequences represented that the isolate belongs to the genus Blastococcus. The diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. Whole-cell sugar analysis of strain GP-S2-8T revealed rhamnose, glucose and mannose as characteristic sugars. The predominant respiratory quinone was MK-9(H4) and the major fatty acids were iso-C16 : 0, iso-C16 : 1 H, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C15 : 0 and iso-C14 : 0. The polar lipid profile included diphosphadidylglycerol, phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, one unidentified glycophospholipid, two unidentified phospholipids and five unidentified lipids. The DNA G+C content was 74.2 mol%. DNA-DNA relatedness values between strain GP-S2-8T and type strains of the genus Blastococcus ranged from 14.6 to 48.6 %. On the basis of the phenotypic differences and DNA-DNA relatedness data, the isolate represents a new species of the genus Blastococcus, for which the name Blastococcuslitoris sp. nov. is proposed. The type strain is GP-S2-8T (=KCCM 43275T=JCM 32354T=DSM 106127T=KCTC 49078T).

Blastococcus atacamensis sp. nov., a novel strain adapted to life in the Yungay core region of the Atacama Desert

A polyphasic study was undertaken to establish the taxonomic status of a Blastococcus strain isolated from an extreme hyper-arid Atacama Desert soil. The isolate, strain P6T, was found to have chemotaxonomic and morphological properties consistent with its classification in the genus Blastococcus. It was shown to form a well-supported branch in the Blastococcus 16S rRNA gene tree together with the type strains of Blastococcus capsensis and Blastococcus saxobsidens and was distinguished from the latter, its close phylogenetic neighbour, by a broad range of phenotypic properties. The draft genome sequence of isolate P6T showed 84.6 % average nucleotide identity, 83.0 % average amino acid identity and a digital DNA-DNA hybridisation value of 27.8 % in comparison with the genome sequence of B. saxobsidens DSM 44509T, values consistent with its assignment to a separate species. Based on these data it is proposed that isolate P6T (NCIMB 15090T=NRRL B-65468T) be assigned to the genus Blastococcus as Blastococcus atacamensis sp. nov. Analysis of the whole genome sequence of B. atacamensis P6T, with 3778 open reading frames and a genome size of 3.9 Mb showed the presence of genes and gene clusters that encode for properties that reflect its adaptation to the extreme environmental conditions that prevail in Atacama Desert soils.

Blastococcus xanthinilyticus sp. nov., isolated from monument.

A novel, non-motile, coccoid, Gram-stain-positive actinobacterium, designated BMG 862T, was isolated from a marble sample collected from the Bulla Regia monument, Northern Tunisia. Its taxonomic position was determined using a polyphasic approach. Results from chemotaxonomic analyses showed MK-9(H4), MK-8(H4) and MK-9(H2) as the predominant menaquinones. The major polar lipids comprised diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, glycophosphatidylinositol, hydroxy-phosphatidylethanolamine and three unidentified phospholipids. The fatty acids consisted of significant amounts (≥10 %) of iso-C16 : 0, C17 : 1ω8c, iso-C15 : 0 and C16 : 1ω7c. Phylogenetic analysis on the basis of 16S rRNA gene sequence comparisons showed that strain BMG 862T belongs to the genus Blastococcus, being most closely related to Blastococcus saxobsidens (=DSM 44509T) (99.5 %) and Blastococcus capsensis (=DSM 46835T=CECT 8876T) (99.3 %). The genomic DNA G+C content of the organism was 74.7 mol%. Results of DNA-DNA hybridization and physiological tests allowed differentiation of strain BMG 862T from related species. The strain was also characterized by its ability to hydrolyse xanthine. On the basis of phenotypic and molecular characteristics, strain BMG 862T (=DSM 46842T=CECT 8884T) represents the type strain of a novel species of the genus Blastococcus, for which the name Blastococcus xanthinilyticus sp. nov. is proposed.

Blastococcus colisei sp. nov, isolated from an archaeological amphitheatre.

The taxonomic position of an actinobacterial isolate, designated strain BMG 822T, isolated from limestone from the Amphitheater of El Jem (Coliseum Thysdrus), Tunisia, was established using a polyphasic approach. Strain BMG 822T was found to grow well at 30°C and pH 6.5-8.0, and to be coral-coloured, Gram-positive, catalase and oxidase negative. Whole cell hydrolysates contained meso-diaminopimelic acid as the diagnostic diamino acid, glucose, galactose and ribose. The phospholipids detected were diphosphatidylglycerol, phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine, hydroxy-phosphatidylethanolamine, an unidentified glycophospholipid and six unidentified phospholipids. MK-9(H4) was found to be the predominant menaquinone, followed by MK-9(H2) and MK-9. The major cellular fatty acids were identified as iso-C16:0, C18:1 ω9c, C17:1 ω8c and iso-H-C16:1. The G+C content of the DNA (73.2%) is typical of the genus. High degrees of 16S rRNA gene sequence similarity were found with the type strains of the genus Blastococcus (97.1-98.3%) followed by the type strains of Modestobacter (96.8-97.8%). Based on the above data and the phenotypic differences from the type strains ofBlastococcus species, it is proposed that the isolate BMG 822T (=DSM 46837T=CECT 8823T) should be classified as the type strain of a novel species,Blastococcus colisei sp. nov.

Blastococcus capsensis sp. nov., isolated from an archaeological Roman pool and emended description of the genus Blastococcus, B. aggregatus, B. saxobsidens, B. jejuensis and B. endophyticus.

A novel Gram-reaction-positive actinobacterium, designated BMG 804T, was isolated from an archaeological Roman pool located in Gafsa, Tunisia. The strain grew as dry bright orange colonies at 30 °C and pH 6.0-8.0. It contained meso-diaminopimelic acid in the cell wall. The whole-cell sugars consisted of glucose, rhamnose and ribose. Polar lipids present were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, an unidentified glycolipid and two unidentified phospholipids. MK-9(H4) was the predominant menaquinone. The fatty acid profile contained major amounts (>5 %) of C17 : 1ω8c, C16 : 1ω7c, iso-C15 : 0, iso-C16 : 0 and iso-C16 : 1H. The 16S rRNA gene sequence of BMG 804T showed 99.4 % as highest sequence similarity with Blastococcussaxobsidens. DNA-DNA hybridization between strain BMG 804T and B.saxobsidens DSM 44509T was 48.6±6.6 %. The G+C content of the DNA was 73.7 mol%. On the basis of the phenotypic and genotypic characteristics, including DNA-DNA hybridization results, BMG 804T (=DSM 46835T=CECT 8876T) is proposed as the type strain of a novel species Blastococcuscapsensis sp. nov. Emended descriptions of the genus Blastococcus and the species Blastococcus aggregatus, B. saxobsidens, Blastococcus jejuensis and Blastococcus endophyticus are also proposed.

Genome Sequence of Blastococcus saxobsidens DD2, a Stone-Inhabiting Bacterium

Members of the genus Blastococcus have been isolated from sandstone monuments, as well as from sea, soil, plant, and snow samples. We report here the genome sequence of a member of this genus, Blastococcus saxobsidens strain DD2, isolated from below the surface of a Sardinian wall calcarenite stone sample.

Contrasted resistance of stone-dwelling Geodermatophilaceae species to stresses known to give rise to reactive oxygen species

Stones in arid environments are inhabited by actinobacteria of the family Geodermatophilaceae like the genera Blastococcus and Modestobacter frequently isolated from altered calcarenites. Their habitat requires adaptation to light-induced and other stresses that generate reactive oxygen species. Here, we show that representative members of the species Blastococcus saxobsidens, Geodermatophilus obscurus, and Modestobacter multiseptatus are differentially adapted to stresses associated with arid environments. Whereas B.saxobsidens was found to be sensitive to gamma radiation (D(10) =900 Gy; 10% survival at 900 Gy), M.multiseptatus was moderately (D(10) =6000 Gy) and G.obscurus was highly tolerant (D(10) =9000 Gy). A difference in resistance to high-frequency (λ value=254nm) UV was shown by B.saxobsidens, M.multiseptatus, and G.obscurus, being sensitive, tolerant, and highly tolerant (D(10) of 6, 900, and >3500kJm(-2) , respectively). Tolerance to desiccation, mitomycin C and hydrogen peroxide correlated with the ionizing radiation and UV resistance profiles of the three species and were correlated with the pigments synthesized. Resistance to heavy metals/metalloids did not follow the same pattern, with resistance to Ag(2+) and Pb(2+) being similar for B.saxobsidens, M.multiseptatus, and G.obscurus, whereas resistance to AsO4 3-, Cr(2+) , or Cu(2+) was greater for B.saxobsidens than for the other two species. The stress resistance profiles of M.multiseptatus and B.saxobsidens were reflected in different calcarenite colonization patterns. While M.multiseptatus was predominantly isolated from the first two millimeters of stone surface, B.saxobsidens was predominantly isolated from the deeper part of the stone where it is better protected from sun irradiation, suggesting that the response to light- and desiccation-induced oxidative stress is an important driver for niche colonization in the stone biotope.

Blastococcus jejuensis sp. nov., an actinomycete from beach sediment, and emended description of the genus Blastococcus Ahrens and Moll 1970

A novel actinomycete, strain KST3-10(T), was isolated from sand sediment of a beach in Jeju, Korea, and was subjected to polyphasic taxonomic characterization. The organism produced circular, smooth, translucent, apricot-coloured colonies comprising coccoid- or rod-shaped cells. Phylogenetic analyses based on 16S rRNA gene sequences showed that the organism belonged to the family Geodermatophilaceae and consistently formed a distinct sub-branch outside the radiation of the genus Blastococcus. The organism showed 16S rRNA gene sequence similarity values of 98.2 % with respect to Blastococcus aggregatus DSM 4725(T) and 98.1 % with respect to Blastococcus saxobsidens BC444(T). The type strains of the two Blastococcus species shared 98.2 % sequence similarity with respect to each other, whereas the levels of sequence similarity between the novel organism and the type strains of the less closely related neighbours, Modestobacter multiseptatus and Geodermatophilus obscurus, were in the range 96.2-96.9 %. The physiological, biochemical and chemotaxonomic data revealed that the novel organism can be readily differentiated from members of the genus Blastococcus and that it merits separate species status. On the basis of the phenotypic and genotypic evidence, strain KST3-10(T) represents a novel species of the genus Blastococcus, for which the name Blastococcus jejuensis sp. nov. is proposed. The type strain is KST3-10(T) (=NRRL B-24440(T)=KCCM 42251(T)).