Complete Genome Sequence of Erythrobacter sp. Strain SDW2, a Marine Bacterium Producing a Yellow Xanthophyll Pigment.

Erythrobacter sp. strain SDW2, which is capable of biosynthesizing a yellow xanthophyll pigment, was isolated from coastal seawater. Here, we report the complete genome sequence of this marine bacterial strain, with a genome size of 2,920,893 bp (64.38% G+C content) and 2,859 genes.

Rapid and Efficient Removal of Anionic Dye in Water Using a Chitosan-Coated Iron Oxide-Immobilized Polyvinylidene Fluoride Membrane.

Anionic dyes are one of the most serious contaminants in water as these molecules are known to be toxic to many living organisms. Herein, we report the development of functionalized polyvinylidene fluoride membranes modified with chitosan-coated iron oxide nanomaterials (Fe-PVDF) for the efficient treatment of anionic dye-contaminated water. Aqueous solutions of anionic dyes could be captured rapidly by passing through the functionalized membrane under reduced pressure. Under neutral conditions, Fe-PVDF showed a maximum removal capacity of 74.6 mg/g for Evans blue (EB) through the adsorption process. In addition, the adsorption capacity was significantly enhanced up to 434.78 mg/g under acidic conditions. The adsorption process for EB matched well with the Langmuir model, indicating monolayer adsorption of the dye to the membrane surface. Moreover, Fe-PVDF can be reusable by a simple washing step in an alkaline solution, and thus, the composite membrane was applied several times without a significant decrease in its adsorption performance. The same composite membrane was further applied to the removal of five other different anionic dyes with high efficiencies. The adsorption mechanism can be explained by the electrostatic interaction between the positively charged chitosan and the negatively charged dye as well as the affinity of the sulfate groups in dye molecules for the surface of the iron oxide nanoparticles. The easy preparation and rapid decolorization procedures make this composite membrane suitable for efficient water treatment.

Isolation and Characterization of a Yellow Xanthophyll Pigment-Producing Marine Bacterium, Erythrobacter sp. SDW2 Strain, in Coastal Seawater.

Xanthophylls, a yellow pigment belonging to the carotenoid family, have attracted much attention for industrial applications due to their versatile nature. We report the isolation of a homo xanthophyll pigment-producing marine bacterium, identified as the Erythrobacter sp. SDW2 strain, from coastal seawater. The isolated Erythrobacter sp. SDW2 strain can produce 263 ± 12.9 mg/L (89.7 ± 5.4 mg/g dry cell weight) of yellow xanthophyll pigment from 5 g/L of glucose. Moreover, the xanthophyll pigment produced by the SDW2 strain exhibits remarkable antioxidative activities, confirmed by the DPPH (73.4 ± 1.4%) and ABTS (84.9 ± 0.7%) assays. These results suggest that the yellow xanthophyll pigment-producing Erythrobacter sp. SDW2 strain could be a promising industrial microorganism for producing marine-derived bioactive compounds with potential for foods, cosmetics, and pharmaceuticals.

Complete Genome Sequence of Cupriavidus sp. Strain EM10, Isolated from Sewage Sludge.

Cupriavidus species have been known as versatile microorganisms in the field of industrial biotechnology. Cupriavidus sp. strain EM10 was isolated from sewage sludges. Here, we report the complete genome sequence of this bacterium, which contains 6,658,510 bp (GC content, 65.12%) and 6,248 genes.

Effects of Conserved Wedge Domain Residues on DNA Binding Activity of Deinococcus radiodurans RecG Helicase.

Deinococcus radiodurans is extremely resistant to ionizing radiation and has an exceptional ability to repair DNA damage caused by various DNA-damaging agents. D. radiodurans uses the same DNA-repair strategies as other prokaryotes, but certain proteins involved in the classical DNA repair machinery have characteristics different from their counterparts. RecG helicase, which unwinds a variety of branched DNA molecules, such as Holliday junctions (HJ) and D-loops, plays important roles in DNA repair, recombination, and replication. Primary sequence analysis of RecG from a number of bacterial species revealed that three amino acids (QPW) in the DNA-binding wedge domain (WD) are well-conserved across the Deinococcus RecG proteins. Interactions involving these conserved residues and DNA substrates were predicted in modeled domain structures of D. radiodurans RecG (DrRecG). Compared to the WD of Escherichia coli RecG protein (EcRecG) containing FSA amino acids corresponding to QPW in DrRecG, the HJ binding activity of DrRecG-WD was higher than that of EcRecG-WD. Reciprocal substitution of FSA and QPW increased and decreased the HJ binding activity of the mutant WDs, EcRecG-WDQPW, and DrRecG-WDFSA, respectively. Following γ-irradiation treatment, the reduced survival rate of DrRecG mutants (ΔrecG) was fully restored by the expression of DrRecG, but not by that of EcRecG. EcRecGQPW also enhanced γ-radioresistance of ΔrecG, whereas DrRecGFSA did not. ΔrecG cells complemented in trans by DrRecG and EcRecGQPW reconstituted an intact genome within 3 h post-irradiation, as did the wild-type strain, but ΔrecG with EcRecG and DrRecGFSA exhibited a delay in assembly of chromosomal fragments induced by γ-irradiation. These results suggested that the QPW residues facilitate the association of DrRecG with DNA junctions, thereby enhancing the DNA repair efficiency of DrRecG.

Rapid Diagnosis of Coronavirus by RNA-Directed RNA Transcription Using an Engineered RNA-based Platform.

A coronavirus disease (COVID-19) outbreak associated with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been spreading widely through person-to-person transmission. Various detection approaches have been developed involving quantitative polymerase chain reaction (qPCR) methods, CRISPR-based systems, and direct targeting of specific coronavirus proteins. However, there have only been a few reports on the detection of RNA-dependent RNA polymerase (RdRP), the primer-independent RNA-replicable protein produced by the RNA genes of coronavirus. Here, we introduce a novel diagnostic methodology for COVID-19 using the RNA-directed and de novo RNA replicable function of RdRP. We devised an RNA platform for RdRP-induced transcription (RPRIT) that includes an RNA template that can be directly transcribed by RdRP. By utilizing RPRIT, the presence of RdRP can be readily confirmed within 30 min using isothermal incubation without PCR. This RdRP detection method can provide a new route for rapid diagnosis of RNA virus-infected patients.

Metabolic Engineering of Extremophilic Bacterium Deinococcus radiodurans for the Production of the Novel Carotenoid Deinoxanthin.

Deinoxanthin, a xanthophyll derived from Deinococcus species, is a unique organic compound that provides greater antioxidant effects compared to other carotenoids due to its superior scavenging activity against singlet oxygen and hydrogen peroxide. Therefore, it has attracted significant attention as a next-generation organic compound that has great potential as a natural ingredient in a food supplements. Although the microbial identification of deinoxanthin has been identified, mass production has not yet been achieved. Here, we report, for the first time, the development of an engineered extremophilic microorganism, Deinococcus radiodurans strain R1, that is capable of producing deinoxanthin through rational metabolic engineering and process optimization. The genes crtB and dxs were first introduced into the genome to reinforce the metabolic flux towards deinoxanthin. The optimal temperature was then identified through a comparative analysis of the mRNA expression of the two genes, while the carbon source was further optimized to increase deinoxanthin production. The final engineered D. radiodurans strain R1 was able to produce 394 ± 17.6 mg/L (102 ± 11.1 mg/g DCW) of deinoxanthin with a yield of 40.4 ± 1.2 mg/g sucrose and a productivity of 8.4 ± 0.2 mg/L/h from 10 g/L of sucrose. The final engineered strain and the strategies developed in the present study can act as the foundation for the industrial application of extremophilic microorganisms.

Extremophilic Microorganisms for the Treatment of Toxic Pollutants in the Environment.

As concerns about the substantial effect of various hazardous toxic pollutants on the environment and public health are increasing, the development of effective and sustainable treatment methods is urgently needed. In particular, the remediation of toxic components such as radioactive waste, toxic heavy metals, and other harmful substances under extreme conditions is quite difficult due to their restricted accessibility. Thus, novel treatment methods for the removal of toxic pollutants using extremophilic microorganisms that can thrive under extreme conditions have been investigated during the past several decades. In this review, recent trends in bioremediation using extremophilic microorganisms and related approaches to develop them are reviewed, with relevant examples and perspectives.

High-Yield Production of Lycopene from Corn Steep Liquor and Glycerol Using the Metabolically Engineered Deinococcus radiodurans R1 Strain.

Developing a highly efficient and ecofriendly system to produce desired products from waste can be considered important to a sustainable society. Here, we report for the first time high-yield production of lycopene through metabolically engineering an extremophilic microorganism, Deinococcus radiodurans R1, from corn steep liquor (CSL) and glycerol. First, the crtLm gene-encoding lycopene cyclase was deleted to prevent the conversion of lycopene to γ-carotene. Then, the crtB gene-encoding phytoene synthase and the dxs gene-encoding 1-deoxy-d-xylulose 5-phosphate synthase were overexpressed to increase carbon flux toward lycopene. The engineered ΔcrtLm/crtB+dxs+ D. radiodurans R1 could produce 273.8 mg/L [80.7 mg/g dry cell weight (DCW)] and 373.5 mg/L (108.0 mg/g DCW) of lycopene from 10 g/L of glucose with 5 g/L of yeast extract and 9.9 g/L of glucose with 20 g/L of CSL, respectively. Moreover, the lycopene titer and content were increased by 26% (470.6 mg/L) and 28% (138.2 mg/g DCW), respectively, when the carbon source was changed to glycerol. Finally, fed-batch fermentation of the final engineered strain allowed the production of 722.2 mg/L (203.5 mg/g DCW) of lycopene with a yield and productivity of 20.3 mg/g glycerol and 6.0 mg/L/h, respectively, from 25 g/L of CSL and 35.7 g/L of glycerol.

Highly Efficient and Stable Removal of Arsenic by Live Cell Fabricated Magnetic Nanoparticles.

As concerns about public health and environmental problems regarding contamination by toxic substances increase worldwide, the development of a highly effective and specific treatment method is imperative. Although physicochemical arsenic treatment methods have been developed, microbial in vivo remediation processes using live cell fabricated nanoparticles have not yet been reported. Herein, we report the development of magnetic iron nanoparticles immobilized an extremophilic microorganism, Deinococcus radiodurans R1, capable of removing toxic arsenic species. First, in vivo synthesis of magnetic iron nanoparticles was successfully achieved with the D. radiodurans R1 strain and characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), dynamic light scattering (DLS), zeta-potential, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analysis. Second, the maximum removal capacity of the magnetic iron nanoparticle-immobilized D. radiodurans R1 strain (DR-FeNPs) for arsenic [As(V)] was evaluated under the optimized conditions. Finally, the removal capacity of DR-FeNPs in the presence of various competitive anions was also investigated to simulate the practical application. More than 98% of As(V) was efficiently removed by DR-FeNPs within 1 h, and the removal efficiency was stably maintained for up to 32 h (98.97%). Furthermore, the possibility of recovery of DR-FeNPs after use was also suggested using magnets as a proof-of-concept.

Metabolic Engineering of Deinococcus radiodurans for the Production of Phytoene.

A metabolically-engineered Deinococcus radiodurans R1 strain capable of producing phytoene, a colorless C40 carotenoid and a promising antioxidant, has been developed. To make this base strain, first, the crtI gene encoding phytoene desaturase was deleted to block the conversion of phytoene to other carotenoids such as lycopene and γ-carotene. This engineered strain produced 0.413 ± 0.023 mg/l of phytoene from 10 g/l of fructose. Further enhanced production of phytoene up to 4.46 ± 0.19 mg/l was achieved by overexpressing the crtB gene encoding phytoene synthase and the dxs genes encoding 1-deoxy-D-xylulose-5-phosphate synthase gene, and by deleting the crtD gene. High cell-density culture of our final engineered strain allowed production of 10.3 ± 0.85 mg/l of phytoene with the yield and productivity of 1.04 ± 0.05 mg/g and 0.143 ± 0.012 mg/l/h, respectively, from 10 g/l of fructose. Furthermore, the antioxidant potential of phytoene produced by the final engineered strain was confirmed by in vitro DPPH radical-scavenging assay.

Silver Nanomaterial-Immobilized Desalination Systems for Efficient Removal of Radioactive Iodine Species in Water.

Increasing concerns regarding the adverse effects of radioactive iodine waste have inspired the development of a highly efficient and sustainable desalination process for the treatment of radioactive iodine-contaminated water. Because of the high affinity of silver towards iodine species, silver nanoparticles immobilized on a cellulose acetate membrane (Ag-CAM) and biogenic silver nanoparticles containing the radiation-resistant bacterium Deinococcus radiodurans (Ag-DR) were developed and investigated for desalination performance in removing radioactive iodines from water. A simple filtration of radioactive iodine using Ag-CAM under continuous in-flow conditions (approximately 1.5 mL/s) provided an excellent removal efficiency (>99%) as well as iodide anion-selectivity. In the bioremediation study, the radioactive iodine was rapidly captured by Ag-DR in the presence of high concentration of competing anions in a short time. The results from both procedures can be visualized by using single-photon emission computed tomography (SPECT) scanning. This work presents a promising desalination method for the removal of radioactive iodine and a practical application model for remediating radioelement-contaminated waters.

Efficient bioremediation of radioactive iodine using biogenic gold nanomaterial-containing radiation-resistant bacterium, Deinococcus radiodurans R1.

We herein report a new bioremediation method using a radiation-resistant bacterium. Biogenic gold nanomaterial-containing Deinococcus radiodurans R1 showed excellent capability for the removal of radioactive iodine (>99%) in several aqueous solutions. These observations demonstrated that our remediation system would be efficiently applied to the treatment of radioactive wastes.

Deinococcus ruber sp. nov., a radiation-resistant bacterium isolated from soil.

Two gamma- and UVC-resistant bacterial strains, designated JSH3-1T and 9-2-2, were isolated from garden soil in South Korea. Cells were Gram-stain-positive, aerobic, non-motile and spherical. A polyphasic approach was used to study the taxonomic properties of strains JSH3-1T and 9-2-2. Phylogenetic analysis based on nearly full-length 16S rRNA gene sequences of strains JSH3-1T and 9-2-2 indicated highest similarity with Deinococcus radiomollis PO-04-20-132T (94.7 and 94.9 %, respectively); levels of sequence similarity with the type strains of other Deinococcus species were less than 94.0 %. Strains JSH3-1T and 9-2-2 shared relatively high 16S rRNA gene sequence similarity (98.7 %) and had a high DNA reassociation value of 81±0.5 %. Meanwhile, they showed low levels of DNA reassociation (<25 %) with other closely related species of the genus Deinococcus. The two strains showed chemotaxonomic features typical of the genus Deinococcus, with the presence of menaquinone 8 as the respiratory quinone. The predominant fatty acids were iso-C17 : 0, iso-C13 : 0 and anteiso-C13 : 0. The polar lipids comprised phosphoglycolipid, aminophospholipid, glycolipid and unknown aminolipids. The DNA G+C contents of strains JSH3-1T and 9-2-2 were 62.0 and 61.9 mol%, respectively. On the basis of their phenotypic and genotypic characteristics, and phylogenetic distinction, strains JSH3-1T (=KCTC 33790T=JCM 31311T) and 9-2-2 (=KCTC 33789=JCM 31310) should be classified within a novel species of the genus Deinococcus, for which the name Deinococcus ruber sp. nov. is proposed.

Deinococcus sedimenti sp. nov. isolated from river sediment.

A novel Gram-positive, oval-shaped, non-motile bacterium designated strain 16F1LT was isolated from sediment collected from the Han River in Seoul, Republic of Korea. Based on the 16S rRNA gene sequence (1,448 bp), this strain was identified as a member of the genus Deinococcus that belongs to the class Deinococci. Similarities in the 16S rRNA gene sequence were shown with Deinococcus daejeonensis MJ27T (99.0%), D. grandis DSM 3963T (98.1%), D. radiotolerans C1T (97.5%), and D. caeni Ho-08T (97.2%). Strain 16F1LT was classified as a different genomic species from closely related Deinococcus members, based on less than 70% DNA-DNA relatedness. Genomic DNA G+C content of strain 16F1LT was 67.2 mol%. Strain 16F1LT was found to grow at temperatures of 10-37°C (optimum 25°C) and pH 7-8 (optimum pH 7) on R2A medium, and was catalase-positive and oxidase-negative. Strain 16F1LT showed resistance to gamma radiation (D10 > 2 kGy). In addition, this strain had the following chemotaxonomic characteristics: the major fatty acids were C15:1 ω6c and C16:1 ω7c; the polar lipid profile contained phosphoglycolipids, unknown aminophospholipids, an unknown aminoglycolipid, unknown aminolipids, an unknown glycolipid, an unknown phospholipid, and an unknown polar lipid; the major quinone was MK-8. Phylogenetic, genotypic, phenotypic, and chemotaxonomic characteristics indicated that strain 16F1LT represents a novel species within the genus Deinococcus, for which the name Deinococcus sedimenti sp. nov. is proposed. The type strain is 16F1LT (=KCTC 33796T =JCM 31405T).

Deinococcus persicinus sp. nov., a radiation-resistant bacterium from soil.

Two Gram-stain-negative, oxidase-negative, catalase-positive, aerobic and coccus-shaped bacterial strains, KSY3-6T and JSH6-18, were isolated from soil in South Korea. Strains KSY3-6T and JSH6-18 showed high resistance to gamma-ray and UVC irradiation. The 16S rRNA gene sequences of strains KSY3-6T and JSH6-18 showed a novel subline within the genus Deinococcus in the family Deinococcaceae. They shared 94.8-86.4 % nucleotide similarities with other species of the genus Deinococcus. Strain KSY3-6T exhibited high DNA-DNA hybridization values with JSH6-18 (77±0.8 %). The two strains showed typical chemotaxonomic characteristics of the genus Deinococcus, including the presence of menaquinone 8 (MK-8) as predominant respiratory quinone and C16 : 0, C17 : 0cyclo and summed feature 3 (C16 : 1ω7c/C16: 1ω6c) as major fatty acids. The G+C content of the DNA of strains KSY3-6T and JSH6-18 was 62.0 and 62.4 mol%, respectively. Polar lipids in strains KSY3-6T and JSH6-18 were mainly phosphoglycolipids. Based on their phenotypic and genotypic properties, strains KSY3-6T and JSH6-18 should be classified as representatives of a novel species in the genus Deinococcus, for which the name Deinococcus persicinus sp. nov. is proposed. The type strain is KSY3-6T (=KCTC 33787T=JCM 31313T). The reference strain is JSH6-18 (=KCTC 33788=JCM 31312).

Deinococcus seoulensis sp. nov., a bacterium isolated from sediment at Han River in Seoul, Republic of Korea.

Strain 16F1E(T) was isolated from a 3-kGy-irradiated sediment sample collected at Han River in Seoul, Republic of Korea. Cells of this strain were observed to be Gram-positive, pililike structure, and short rod shape, and colonies were red in color. The strain showed the highest degree of 16S rRNA gene sequence similarity to Deinococcus aquaticus PB314(T) (98.8%), Deinococcus depolymerans TDMA-24(T) (98.1%), Deinococcus caeni Ho-08(T) (98.0%), and Deinococcus grandis DSM 3963(T) (97.0%). 16S rRNA gene sequence analysis identified this strain as a member of the genus Deinococcus (Family: Deinococcaceae). The genomic DNA G+C content of strain 16F1ET was 66.9 mol%. The low levels of DNA-DNA hybridization (< 56.2%) with the species mentioned above identified strain 16F1E(T) as a novel Deinococcus species. Its oxidase and catalase activities as well as the production of acid from glucose were positive. Growth of the strain was observed at 10-37°C (optimum: 20-30°C) and pH 4-10 (optimum: pH 7-8). The cells tolerated less than 5% NaCl and had low resistance to gamma radiation (D10 < 4 kGy). Strain 16F1ET possessed the following chemotaxonomic characteristics: C16:0, C15:1 ω6c, and C16:1 ω7c as the major fatty acids; phosphoglycolipid as the predominant polar lipid; and menaquinone-8 as the predominant respiratory isoprenoid quinone. Based on the polyphasic evidence, as well as the phylogenetic, genotypic, phenotypic, and chemotaxonomic characterization results, strain 16F1E(T) (=KCTC 33793(T) =JCM 31404(T)) is proposed to represent the type strain of a novel species, Deinococcus seoulensis sp. nov.

Spirosoma fluminis sp. nov., a Gamma-Radiation Resistant Bacterium Isolated from Sediment of the Han River in South Korea.

A Gram-negative, long rod-shaped, and yellowish bacterium, designated as strain 15J17T(T), was isolated from sediment of the Han River in South Korea after exposure to 3 kGy of gamma radiation. The strain was catalase- and oxidase-positive and showed resistance to gamma radiation-D10 value (i.e., the dose required to reduce the bacterial population by 10-fold) of >4 kGy. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that the strain belonged to the genus Spirosoma and showed moderate degrees of sequence similarity with related species (90.6-93.5 %). Chemotaxonomic data revealed that the strain contained summed feature 3 (C16:1 ω7c/C16:1 ω6c), C16:1 ω5c, C16:0, C18:0, and C15:0 iso as the major fatty acids; phosphatidylethanolamine, an unidentified aminophospholipid, and an unidentified polar lipid as the major polar lipids; and menaquinone-7 (MK-7) as the major quinone. The genomic DNA G+C content of the new strain was 48.3 mol%. Based on these data, type strain 15J17T(T) (=KCTC 52198(T) = JCM 31409(T)) should be classified as representing a new species, for which we propose the name Spirosoma fluminis sp. nov.

PprM is necessary for up-regulation of katE1, encoding the major catalase of Deinococcus radiodurans, under unstressed culture conditions.

Deinococcus radiodurans is a poly-extremophilic organism, capable of tolerating a wide variety of different stresses, such as gamma/ultraviolet radiation, desiccation, and oxidative stress. PprM, a cold shock protein homolog, is involved in the radiation resistance of D. radiodurans, but its role in the oxidative stress response has not been investigated. In this study, we investigated the effect of pprM mutation on catalase gene expression. pprM disruption decreased the mRNA and protein levels of KatE1, which is the major catalase in D. radiodurans, under normal culture conditions. A pprM mutant strain (pprM MT) exhibited decreased catalase activity, and its resistance to hydrogen peroxide (H2O2) decreased accordingly compared with that of the wild-type strain. We confirmed that RecG helicase negatively regulates katE1 under normal culture conditions. Among katE1 transcriptional regulators, the positive regulator drRRA was not altered in pprM (-), while the negative regulators perR, dtxR, and recG were activated more than 2.5-fold in pprM MT. These findings suggest that PprM is necessary for KatE1 production under normal culture conditions by down-regulation of katE1 negative regulators.

The three catalases in Deinococcus radiodurans: Only two show catalase activity.

Deinococcus radiodurans, which is extremely resistant to ionizing radiation and oxidative stress, is known to have three catalases (DR1998, DRA0146, and DRA0259). In this study, to investigate the role of each catalase, we constructed catalase mutants (Δdr1998, ΔdrA0146, and ΔdrA0259) of D. radiodurans. Of the three mutants, Δdr1998 exhibited the greatest decrease in hydrogen peroxide (H2O2) resistance and the highest increase in intracellular reactive oxygen species (ROS) levels following H2O2 treatments, whereas ΔdrA0146 showed no change in its H2O2 resistance or ROS level. Catalase activity was not attenuated in ΔdrA0146, and none of the three bands detected in an in-gel catalase activity assay disappeared in ΔdrA0146. The purified His-tagged recombinant DRA0146 did not show catalase activity. In addition, the phylogenetic analysis of the deinococcal catalases revealed that the DR1998-type catalase is common in the genus Deinococcus, but the DRA0146-type catalase was found in only 4 of 23 Deinococcus species. Taken together, these results indicate that DR1998 plays a critical role in the anti-oxidative system of D. radiodurans by detoxifying H2O2, but DRA0146 does not have catalase activity and is not involved in the resistance to H2O2 stress.