Antioxidant Activity Evaluation of FlexirubinType Pigment from Chryseobacterium artocarpi CECT 8497 and Related Docking Study.

The current research is focused on studying the biological efficacy of flexirubin, a pigment extracted from Chryseobacterium artocarpi CECT 8497.Different methods such as DPPH, H2O2, NO•, O2•-, •OH, lipid peroxidation inhibition by FTC and TBA, ferric reducing and ferrous chelating activity were carried out to evaluate the antioxidant activity of flexirubin. Molecular docking was also carried out, seeking the molecular interactions of flexirubin and a standard antioxidant compound with SOD enzyme to figure out the possible flexirubin activity mechanism. The new findings revealed that the highest level of flexirubin exhibited similar antioxidant activity as that of the standard compound according to the H2O2, •OH, O2•-, FTC and TBA methods. On the other hand, flexirubin at the highest level has shown lower antioxidant activity than the positive control according to the DPPH and NO• and even much lower when measured by the FRAP method. Molecular docking showed that the interaction of flexirubin was in the binding cavity of the SOD enzyme and did not affect its metal-binding site. These results revealed that flexirubin has antioxidant properties and can be a useful therapeutic compound in preventing or treating free radical-related diseases.

Chryseobacterium antibioticum sp. nov. with antimicrobial activity against Gram-negative bacteria, isolated from Arctic soil.

A yellow-pigmented, non-motile, Gram-stain-negative, pleomorphic bacterium, designated RP-3-3T was obtained from soil sampled at the Arctic region in Cambridge Bay, NU, Canada. The strain is strictly aerobic, psychrotolerant, grow optimally at 15-20 °C and produces flexirubin type pigments. The strain is able to hydrolyse CM-cellulose, casein, starch and DNA. Strain RP-3-3T showed antimicrobial activity against Gram-negative pathogens. A phylogenetic analysis based on its 16S rRNA gene sequence revealed that strain RP-3-3T formed a lineage within the family Weeksellaceae and clustered as members of the genus Chryseobacterium. The closest members were Chryseobacterium shigense DSM 17126T (98.7% sequence similarity), Chryseobacterium carnipullorum DSM 25581T (98.7%) and Chryseobacterium oncorhychi 701B-08T (98%). The genome is 4,910,468 bp long with 73 scaffolds and 4300 protein-coding genes. The anti-SMASH analysis of whole genome showed ten putative biosynthetic gene clusters responsible for various secondary metabolites. The sole respiratory quinone is MK-6. The major cellular fatty acids are iso-C15:0, iso-C17:1 ω9c, iso-C17:0 3-OH, summed feature 3 (iso-C15 :0 2-OH/C16 :1ω7c) and anteiso-C15:0. The major polar lipid is phosphatidylethanolamine. The DNA G + C content of the type strain is 36.9 mol%. In addition, the average nucleotide identity and in silico DNA-DNA hybridization  relatedness values between strain RP-3-3T and phylogenetically closest members are below the threshold value for species delineation. Based on genomic, chemotaxonomic, phenotypic and phylogenetic analyses, strain RP-3-3T represents novel species in the genus Chryseobacterium, for which the name Chryseobacterium antibioticum sp. nov. is proposed. The type strain is RP-3-3T (=KACC 21620T = NBRC 114360T).

Volatiles from the Psychrotolerant Bacterium Chryseobacterium polytrichastri.

The flavobacterium Chryseobacterium polytrichastri was investigated for its volatile profile by use of a closed-loop stripping apparatus (CLSA) and subsequent GC-MS analysis. The analyses revealed a rich headspace extract with 71 identified compounds. Compound identification was based on a comparison to library mass spectra for known compounds and on a synthesis of authentic standards for unknowns. Important classes were phenylethyl amides and a series of corresponding imines and pyrroles.

The regulatory mechanism of Chryseobacterium sp. resistance mediated by montmorillonite upon cadmium stress.

Cadmium (Cd) is a toxic heavy metal and its uptake by living organisms causes adverse effect, further resulting in cycle pollution of the biosphere. The specific regulatory mechanism between clays and microbes under Cd stress remains unclear. In this study, interface interactions among clays, microbes and Cd were confirmed. Comparative transcriptome was conducted to investigate how it regulated gene expression patterns of microbes (Chryseobacterium sp. WAL2), which exposed to a series of gradient concentrations of Cd (16, 32, 64 and 128 µg mL-1) for 12 d in the presence and absence of clay montmorillonite (Mt) (16 g L-1). Cd was highly enriched by the unique interface interactions between Mt and bacteria (67.6-82.1%), leading to a more hostile environment for bacterial cells. However, Mt ultimately enhanced bacterial resistance to Cd stress by stimulating the mechanism of bacterial resistance; namely: (i) Mt increased genes expression connected with ion transport, enhancing the uptake of Cd; (ii) Mt stimulated genes expression related to efflux pump and positively regulated cellular oxidative stress (e.g., glutathione) and Cd accumulation (e.g., cysteine) processes. Further, genes expression related to intracellular metabolic processes was enforced, which supplied a driving force and accelerated electron transfer; (iii) Mt improved genes expression involved in DNA replication and other biological processes (e.g., terpenoid backbone biosynthesis) to maintain bacterial vitality. Therefore, the study not only optimized a unique Cd resistance mechanism of Mt on Chryseobacterium sp., but also provided a novel insight for environmental mitigation of heavy metals from the perspective of molecular biology.

Draft genome and description of Chryseobacterium phocaeense sp. nov.: a new bacterial species isolated from the sputum of a cystic fibrosis patient.

Strain 6021061333T was isolated from the sputum of 16-year-old girl with cystic fibrosis following a pulmonary exacerbation. This bacterial strain could not be identified by our systematic MALDI-TOF mass spectrometry screening on a MicroFlex. This led to the sequencing of the 16S rRNA gene, which shows 97.83% sequence identity with Chryseobacterium kwangjuense strain KJ1R5T, the phylogenetic closely related type strain of a species with standing in nomenclature, which putatively classifies it as a new species. Colonies are yellow, circular and 0.5-1 mm in diameter after cultivation at 28 °C for 24 h on 5% sheep blood-enriched Colombia agar. Growth occurs at temperatures in the range of 28-37 °C (optimally at 28 °C). Strain 6021061333T is Gram-negative, non-motile and strictly aerobic bacillus. It is catalase and oxidase positive. The 4,864,678 bp-long genome, composed of five contigs, has a G+C content of 38.86%. Out of the 4427 predicted genes, 4342 were protein-coding genes and 85 were RNAs. The major fatty acids are branched (13-methyl-tetradecanoic acid and 15-methyl-hexadecenoic acid). Digital DNA-DNA hybridization (dDDH) estimation and average nucleotide identity (ANI) of the strain 6021061333T against genomes of the type strains of related species ranged between 23.60 and 50.40% and between 79.31 and 93.06%, respectively. According to our taxonogenomics results, we propose the creation of Chryseobacterium phocaeense sp. nov. that contains the type strain 6021061333T (= CSUR P2660, = CECT 9670).

Microbial antimonate reduction with a solid-state electrode as the sole electron donor: A novel approach for antimony bioremediation.

The anaerobic antimonate [Sb(V)] reduction with a solid-state electrode serving as the sole electron donor was demonstrated by employing a bioelectrochemical system. The highest Sb(V) reduction efficiency was observed at the biocathode potential of -0.7 V versus standard hydrogen electrode using a cathode potential range from -0.5 V to -1.1 V. The scanning electron microscopy and energy dispersive X-ray spectroscopy indicated that both amorphous and crystallized Sb2O3 were formed as products of Sb(V) reduction. The irreversible recovery of bioelectrochemical Sb(V), when the cathode potential deviated from the optimal potential, was explained through the alteration in microbial communities, which was further elucidated by the next-generation sequencing of 16S rRNA gene amplicons. Chryseobacterium koreense and Stenotrophomonas nitritireducens were the dominant species of microbial consortia at Sb(V)-reducing biocathodes. This study revealed a novel option for bioremediation of Sb at underground contaminated sites, where the delivery of organic electron donors is limited or ineffective.

Extraction and partial characterisation of antioxidant pigment produced by Chryseobacterium sp. kr6.

Pigments synthesised by Chryseobacterium sp. kr6 growing on feather waste were extracted and characterised. The pigment extract was characterised by KOH test, UV-vis, CIELAB colour system, HPLC-DAD-MS, FTIR and its antioxidant capacity was evaluated. A positive bathochromic shift was observed when kr6 colonies or pigment extracts were subjected to alkaline solution (20% KOH) and a λmax at 450 nm was detected for acetone extracts, although no typical fine structure of carotenoids was detected in the electomagnetic spectra. The HPLC profile of the extracted pigment showed that the compound has three different peaks with λmax near 450 nm. The FTIR analysis shows some principal functional groups from a flexirubin-like molecule. The pigmented compound also presents antioxidant activity evaluated by the scavenging of the ABTS radical.

Comparison of the Vitek MS and Bruker Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Systems for Identification of Chryseobacterium Isolates from Clinical Specimens and Report of Uncommon Chryseobacterium Infections in Humans.

Matrix-assisted laser desorption ionization-time of flight mass spectrometry is becoming more popular and is replacing traditional identification methods in the clinical microbiology laboratory. We aimed to compare the Vitek mass spectrometry (MS) and Bruker Biotyper systems for the identification of Chryseobacterium isolated from clinical specimens and to report uncommon Chryseobacterium infections in humans. The microbial database from a hospital was searched for records between 2005 and 2016 to identify cultures that yielded Chryseobacterium Species identification by the Vitek MS and Bruker Biotyper systems was compared to identification by 16S rRNA gene sequencing. Over the study period, 140 Chryseobacterium isolates were included. Based on 16S rRNA gene sequencing, 78 isolates were C. indologenes, 39 were C. gleum, 12 were uncommon Chryseobacterium species (C. arthrosphaerae, C. culicis, C. cucumeris, C. bernardetii, C. artocarpi, and C. daecheongense), and the remaining 11 isolates were only identified at the genus level. The Vitek MS and Bruker Biotyper systems correctly identified 98.7% and 100% of C. indologenes isolates, respectively. While the Bruker Biotyper accurately identified 100% of C. gleum isolates, the Vitek MS system correctly identified only 2.6% of isolates from this species. None of the uncommon Chryseobacterium species were successfully identified by either of these two systems. The overall accuracies of Chryseobacterium identification at the species level by the Vitek MS and Bruker Biotyper systems were 60.5% and 90.7%, respectively. An upgrade and correction of the Vitek MS and Bruker Biotyper databases is recommended to correctly identify Chryseobacterium species.

Homology modeling and prediction of the amino acid residues participating in the transfer of acetyl-CoA to arylalkylamine by the N-acetyltransferase from Chryseobacterium sp.

OBJECTIVES: To predict the amino acid residues playing important roles in acetyl-CoA and substrate binding and to study the acetyl group transfer mechanism of Chryseobacterium sp. 5-3B N-acetyltransferase (5-3B NatA). RESULTS: A 3-dimensional homology model of 5-3B NatA was constructed to compare the theoretical structure of this compound with the structures of previously reported proteins belonging to the bacterial GCN5 N-acetyltransferase family. Homology modeling of the 5-3B NatA structure and a characterization of the enzyme's kinetic parameters identified the essential amino acid residues involved in binding and acetyl-group transfer. 126Leu, 132Leu, and 135Lys were implicated in the binding of phosphopantothenic acid, and 100Tyr and 131Lys in that of adenosyl biphosphate. The data supported the participation of 83Glu and 133Tyr in catalyzing acetyl-group transfer to L-2-phenylglycine. CONCLUSIONS: 5-3B NatA catalyzes the enantioselective N-acetylation of L-2-phenylglycine via a ternary complex comprising the enzyme, acetyl-CoA, and the substrate.

Description of Chryseobacterium timonianum sp. nov., isolated from a patient with pneumonia.

Using a polyphasic taxonomic strategy, an aerobic, Gram-negative, non-motile, yellow pigmented rod isolated from a sputum sample of a patient with pneumonia was characterised. This bacterial strain, designated G972T, could not be identified by our systematic MALDI-TOF screening on a MicroFlex. This led to the sequencing of the 16S rRNA gene, which shows 98.57% sequence identity with that of Chryseobacterium indologenes 16777T, the phylogenetic closely related type strain of a species with standing in nomenclature, which putatively classifies it as a new species. The major cell fatty acids were identified as 13-methyl-tetradecanoic acid (61%), 3-hydroxy-heptadecanoic acid (16%) and 15-methyl-11-hexadecenoic acid (11%). D-glucose, D-mannose, aesculin, D-maltose, D-trehalose, and gentibiose are the main carbon source. Digital DNA-DNA hybridization (dDDH) estimation and average nucleotide identity values (ANI) of the strain G972T against genomes of the type strains of related species ranged between 18.9 and 32.8% and between 71.46 and 83.61%, respectively, thus confirming again the new species status of the strain. Here, we describe the characteristics of this organism, complete genome sequence and annotation. The 5,390,132 bp size genome contains 4867 protein-coding genes, 89 RNAs (three genes are 5S rRNA, one gene is 16S rRNA, one gene is 23S rRNA and 84 tRNAs) with 35.51% GC content. Finally, on the basis of these polyphasic data, consisting of phenotypic and genomic analyses, we conclude that strain strain G972T (= DSM 103388T = CSUR P2233T) represents a novel species for which we propose the name Chryseobacterium timonianum. The 16S rRNA and genome sequences are available in GenBank database under accession numbers LT161886 and FJVD00000000.

Synthesis of flexirubin-mediated silver nanoparticles using Chryseobacterium artocarpi CECT 8497 and investigation of its anticancer activity.

In this work, the synthesis of silver nanoparticles from a pigment produced by a recently-discovered bacterium, Chryseobacterium artocarpi CECT 8497, was achieved, followed by an investigation of its anticancer properties. The bacterial pigment was identified as flexirubin following NMR ((1)H NMR and (13)C NMR), UV-Vis, and LC-MS analysis. An aqueous silver nitrate solution was treated with isolated flexirubin to produce silver nanoparticles. The synthesised silver nanoparticles were subsequently characterised by UV-Vis spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FTIR) Spectroscopy methodologies. Furthermore, the anticancer effects of synthesised silver nanoparticles in a human breast cancer cell line (MCF-7) were evaluated. The tests showed significant cytotoxicity activity of the silver nanoparticles in the cultured cells, with an IC50 value of 36µgmL(-1). This study demonstrates that silver nanoparticles, synthesised from flexirubin from C. artocarpi CECT 8497, may have potential as a novel chemotherapeutic agent.

Rapid asymmetric reduction of ethyl 4-chloro-3-oxobutanoate using a thermostabilized mutant of ketoreductase ChKRED20.

Ethyl (S)-4-chloro-3-hydroxybutanoate ((S)-CHBE) is an important chiral intermediate for the synthesis of "blockbuster" drug statins. The carbonyl reductase ChKRED20 from Chryseobacterium sp. CA49 was found to catalyze the bio-reductive production of (S)-CHBE with excellent stereoselectivity (>99.5 % ee). Perceiving a capacity for improvement, we sought to increase the thermostability of ChKRED20 to allow a higher reaction temperature. After one round of error-prone PCR (epPCR) library screening followed by the combination of beneficial mutations, a triple-mutant MC135 was successfully achieved with substantially enhanced thermostablity. The activity of MC135 at 50 °C was similar to the wild type. However, at its temperature optima of 65 °C, the mutant displayed 63 % increase of activity compared to the wild type and remained >95 % activity after being incubated for 15 days, while the wild type had a half-life of 11.9 min at 65 °C. At a substrate/catalyst ratio of 100 (w/w), the mutant catalyzed the complete conversion of 300 g/l substrate within 1 h to yield enantiopure (S)-CHBE with an isolated yield of 95 %, corresponding to a space-time yield of 1824 mM/h.

Comparison of the growth kinetics and proteolytic activities of Chryseobacterium species and Pseudomonas fluorescens.

The effect of temperature on the growth kinetics and proteolytic activity of Chryseobacterium joostei and Chryseobacterium bovis was determined during this study. The results were compared with the activities of Pseudomonas fluorescens, which is regarded to be a major food spoilage psychrotolerant microorganism. For the growth studies, cultures were incubated in nutrient broth in a temperature gradient incubator (from 9 to 50 °C) and separately at 4 °C, and the optical density was measured at different time intervals. Growth temperature profiles for each organism were constructed. For determination of proteolytic activity, the cultures were incubated in fat-free ultra-high temperature processed milk in the temperature gradient incubator for 72 h (temperature range as above). Cell-free extracts were used to determine the proteolytic activity using the azocasein method. Results of the growth studies showed that C. joostei had the ability to grow over a wider temperature range than C. bovis and P. fluorescens without being affected by changes in the temperature. For the proteolytic activity, C. joostei had significantly (p < 0.001) higher activity per milligram of protein at 15.5 °C, followed by C. bovis and P. fluorescens. The results showed that C. joostei potentially has an even greater spoilage capacity in milk on the basis of growth rate and proteolytic activity than did P. fluorescens.

Structural and Biochemical Characterization of AidC, a Quorum-Quenching Lactonase with Atypical Selectivity.

Quorum-quenching catalysts are of interest for potential application as biochemical tools for interrogating interbacterial communication pathways, as antibiofouling agents, and as anti-infective agents in plants and animals. Herein, the structure and function of AidC, an N-acyl-l-homoserine lactone (AHL) lactonase from Chryseobacterium, is characterized. Steady-state kinetics show that zinc-supplemented AidC is the most efficient wild-type quorum-quenching enzymes characterized to date, with a kcat/KM value of approximately 2 × 10(6) M(-1) s(-1) for N-heptanoyl-l-homoserine lactone. The enzyme has stricter substrate selectivity and significantly lower KM values (ca. 50 µM for preferred substrates) compared to those of typical AHL lactonases (ca. >1 mM). X-ray crystal structures of AidC alone and with the product N-hexanoyl-l-homoserine were determined at resolutions of 1.09 and 1.67 Å, respectively. Each structure displays as a dimer, and dimeric oligiomerization was also observed in solution by size-exclusion chromatography coupled with multiangle light scattering. The structures reveal two atypical features as compared to previously characterized AHL lactonases: a "kinked" α-helix that forms part of a closed binding pocket that provides affinity and enforces selectivity for AHL substrates and an active-site His substitution that is usually found in a homologous family of phosphodiesterases. Implications for the catalytic mechanism of AHL lactonases are discussed.

Biochar in co-contaminated soil manipulates arsenic solubility and microbiological community structure, and promotes organochlorine degradation.

We examined the effect of biochar on the water-soluble arsenic (As) concentration and the extent of organochlorine degradation in a co-contaminated historic sheep-dip soil during a 180-d glasshouse incubation experiment. Soil microbial activity, bacterial community and structure diversity were also investigated. Biochar made from willow feedstock (Salix sp) was pyrolysed at 350 or 550°C and added to soil at rates of 10 g kg-1 and 20 g kg-1 (representing 30 t ha-1 and 60 t ha-1). The isomers of hexachlorocyclohexane (HCH) alpha-HCH and gamma-HCH (lindane), underwent 10-fold and 4-fold reductions in concentration as a function of biochar treatment. Biochar also resulted in a significant reduction in soil DDT levels (P < 0.01), and increased the DDE:DDT ratio. Soil microbial activity was significantly increased (P < 0.01) under all biochar treatments after 60 days of treatment compared to the control. 16S amplicon sequencing revealed that biochar-amended soil contained more members of the Chryseobacterium, Flavobacterium, Dyadobacter and Pseudomonadaceae which are known bioremediators of hydrocarbons. We hypothesise that a recorded short-term reduction in the soluble As concentration due to biochar amendment allowed native soil microbial communities to overcome As-related stress. We propose that increased microbiological activity (dehydrogenase activity) due to biochar amendment was responsible for enhanced degradation of organochlorines in the soil. Biochar therefore partially overcame the co-contaminant effect of As, allowing for enhanced natural attenuation of organochlorines in soil.

Bile acids as modulators of enzyme activity and stability.

Bile acids deactivate certain enzymes, such as prolyl endopeptidases (PEPs), which are investigated as candidates for protease-based therapy for celiac sprue. Deactivation by bile acids presents a problem for therapeutic enzymes targetted to function in the upper intestine. However, enzyme deactivation by bile acids is not a general phenomenon. Trypsin and chymotrypsin are not deactivated by bile acids. In fact, these pancreatic enzymes are more efficient at cleaving large dietary substrates in the presence of bile acids. We targeted the origin of the apparently different effect of bile acids on prolyl endopeptidases and pancreatic enzymes by examining the effect of bile acids on the kinetics of cleavage of small substrates, and by determining the effect of bile acids on the thermodynamic stabilities of these enzymes. Physiological amounts (5 mM) of cholic acid decrease the thermodynamic stability of Flavobacterium meningosepticum PEP from 18.5 ± 2 kcal/mol to 10.5 ± 1 kcal/mol, while thermostability of trypsin and chymotrypsin is unchanged. Trypsin and chymotrypsin activation by bile and PEP deactivation can both be explained in terms of a common mechanism: bile acid-mediated protein destabilization. Bile acids, usually considered non-denaturing surfactants, in this case act as a destabilizing agent on PEP thus deactivating the enzyme. However, this level of global thermodynamic destabilization does not account for a more than 50% decrease in enzyme activity, suggesting that bile acids most likely modulate enzyme activity through specific local interactions.

Identification of fruity aroma-producing compounds from Chryseobacterium sp. isolated from the Western Ghats, India.

A fruity aroma-producing strain WG4 was isolated from a water sample collected from the Western Ghats, India. The 16S rRNA gene sequence analysis of strain WG4 indicated that Chryseobacterium indologenes, a member of the family 'Flavobacteriaceae' is the closest related species with a pair-wise sequence similarity of 98.6%. Strain WG4 produces a fruity aroma when grown on nutrient or trypticase soy agar plates. The fruity aroma is more when the strain WG4 is grown on agar plates compared to their growth in broth. The aromatic compounds produced by the strain WG4 were identified as ester compounds and were confirmed as ethyl-2-methylbutyrate and ethyl-3-methylbutyrate based on Gas Chromatography-Mass Spectrometry (GC-MS) analysis and using standard reference compounds. Even after repeated subcultures strain WG4 produced the same aroma in high intensity. Thus, strain WG4 could serve as a source for the production of these flavour compounds.

Root treatment with rhizobacteria antagonistic to Phytophthora blight affects anthracnose occurrence, ripening, and yield of pepper fruit in the plastic house and field.

We previously selected rhizobacterial strains CCR04, CCR80, GSE09, ISE13, and ISE14, which were antagonistic to Phytophthora blight of pepper. In this study, we investigated the effects of root treatment of rhizobacteria on anthracnose occurrence, ripening, and yield of pepper fruit in the plastic house and field in 2008 and 2009. We also examined the effects of volatiles produced by the strains on fruit ripening and on mycelial growth and spore development of Colletotrichum acutatum and Phytophthora capsici in the laboratory, identifying the volatile compounds by gas chromatography-mass spectrometry (GC-MS). In the house tests, all strains significantly (P < 0.05) reduced anthracnose incidence on pepper fruit; strains GSE09 and ISE14 consistently produced higher numbers of pepper fruit or increased the fresh weight of red fruit more than the controls in both years. In the field tests, all strains significantly (P < 0.05) reduced anthracnose occurrence on either green or red pepper fruit; strain ISE14 consistently produced higher numbers or increased fresh weights of red fruit more than the controls in both years. In the laboratory tests, volatiles produced by strains GSE09 and ISE13 only stimulated maturation of pepper fruit from green (unripe) to red (ripe) fruit; the volatiles of certain strains inhibited the growth and development of C. acutatum and P. capsici. On the other hand, GC-MS analysis of volatiles of strains GSE09 and ISE13 revealed 17 distinct compounds in both strains, including decane, dodecane, 1,3-di-tert-butylbenzene, tetradecane, 2,4-di-tert-butylphenol, and hexadecane. Among these compounds, 2,4-di-tert-butylphenol only stimulated fruit ripening and inhibited growth and development of the pathogens. Taken together, strains GSE09 and ISE14 effectively reduced anthracnose occurrence and stimulated pepper fruit ripening and yield, possibly via bacterial volatiles. Therefore, these two strains could be potential agents for controlling Phytophthora blight and anthracnose, and for increasing fruit ripening and yield. To our knowledge, this is the first report of volatiles such as 2,4-di-tert-butylphenol produced by rhizobacteria being related to both fruit ripening and pathogen inhibition.

Chryseobacterium yonginense sp. nov., isolated from a mesotrophic artificial lake.

A Gram-staining-negative, non-motile, yellow-pigmented bacterial strain, designated HMD1043(T), was isolated from a mesotrophic artificial lake in Korea. The major fatty acids were anteiso-C(15 : 0) (28.3 %), iso-C(15 : 0) (22.9 %), summed feature 9 (comprising iso-C(17 : 1)ω9c and/or 10-methyl C(16 : 0); 8.8 %) and iso-C(13 : 0) (5.3 %). The DNA G+C content was 31.3 mol%. A phylogenetic tree based on 16S rRNA gene sequences showed that strain HMD1043(T) formed a lineage within the genus Chryseobacterium and was most closely related to Chryseobacterium antarcticum AT1013(T) (96.8 % 16S rRNA gene sequence similarity) and Chryseobacterium jeonii AT1047(T) (96.4 %). On the basis of the evidence presented in this study, strain HMD1043(T) is described as belonging to a novel species of the genus Chryseobacterium, for which the name Chryseobacterium yonginense sp. nov. is proposed. The type strain is HMD1043(T) ( = KCTC 22744(T)  = CECT 7547(T)).

Four new species of Chryseobacterium from the rhizosphere of coastal sand dune plants, Chryseobacterium elymi sp. nov., Chryseobacterium hagamense sp. nov., Chryseobacterium lathyri sp. nov. and Chryseobacterium rhizosphaerae sp. nov.

The taxonomic positions of five Gram-negative, non-spore-forming and non-motile bacterial strains isolated from the rhizosphere of sand dune plants were examined using a polyphasic approach. The analysis of the 16S rRNA gene sequence indicated that all of the isolates fell into four distinct phylogenetic clusters belonging to the genus Chryseobacterium of the family Flavobacteriaceae. The 16S rRNA gene sequence similarities of isolates to mostly related type strains of Chryseobacterium ranged from 97.5% to 98.5%. All strains contained MK-6 as the predominant menaquinone, and iso-C(15:0), iso-C(17:0) 3-OH and a summed feature of iso-C(15:0) 2-OH and/or C(16:1) omega7c as the dominant fatty acids. Combined phenotypic, genotypic and chemotaxonomic data supported that they represented four novel species in the genus Chryseobacterium, for which the names Chryseobacterium hagamense sp. nov. (type strain RHA2-9(T)=KCTC 22545(T)=NBRC 105253(T)), Chryseobacterium elymi sp. nov. (type strain RHA3-1(T)=KCTC 22547(T)=NBRC 105251(T)), Chryseobacterium lathyri sp. nov. (type strain RBA2-6(T)=KCTC 22544(T)=NBRC 105250(T)), and Chryseobacterium rhizosphaerae sp. nov. (type strain RSB3-1(T)=KCTC 22548(T)=NBRC 105248(T)) are proposed.