Chryseobacterium metallicongregator, sp. nov., a bacterium possessing metallophore activity towards rare earth elements.

A polyphasic taxonomic study was carried out on strain ES2T, isolated from sediment of a wetland created to remediate acid drainage from a coal mine. The rod-shaped bacterium formed yellow/orange pigmented colonies and produced the pigment flexirubin. The 16S rRNA gene sequence results assigned the strain to Chryseobacterium, with 98.9 and 98.3 % similarity to Chryseobacterium vietnamense and Chryseobacterium cucumeris, respectively. Computation of the average nucleotide identity and digital DNA-DNA hybridization values with the closest phylogenetic neighbours of ES2T revealed genetic differences at the species level, which were further substantiated by differences in several physiological characteristics. The dominant fatty acids of strain ES2T were iso-C15 : 0, iso-C17 : 1 ω9c, iso C17 : 0 3-OH, and iso-C15 : 0 2-OH. The DNA G+C content was 35.5 mol%. The major polar lipid was phosphatidylethanolamine while menaquinone-6 was the only menaquinone found. This bacterium has been previously shown to possess metallophore activity towards rare earth elements, and based on genome sequencing, possesses all required genes for siderophore production/activity, possibly identifying the source of this unique ability. On the basis of the results obtained here, this bacterium is assigned to the genus Chryseobacterium as representing a new species with the name Chryseobacterium metallicongregator sp. nov., type strain ES2T (=NRRL B-65679T=KCTC 102120T).

Kaistella rhinocerotis sp. nov., isolated from the faeces of rhinoceros and reclassification of Chryseobacterium faecale as Kaistella faecalis comb. nov.

Strain Ran72T, a novel Gram-stain-negative, obligately aerobic, non-motile, and rod-shaped bacterium, was isolated from the faeces of the rhinoceros species Ceratotherium simum. The novel bacterial strain grew optimally in Reasoner's 2A medium under the following conditions: 0 % (w/v) NaCl, pH 7.5, and 30 °C. Based on phylogenetic analysis using 16S rRNA gene sequencing, strain Ran72T was found to be most closely related to Chryseobacterium faecale F4T (98.4 %), Kaistella soli DKR-2T (98.0 %), and Kaistella haifensis H38T (97.4 %). A comprehensive genome-level comparison between strain Ran72T with C. faecale F4T, K. soli DKR-2T, and K. haifensis H38T revealed average nucleotide identity, digital DNA-DNA hybridization, and average amino acid identity values of ≤74.9, ≤19.3, and ≤78.7 %, respectively. The major fatty acids were anteiso-C15 : 0 (22.3 %), with MK-6 being the predominant respiratory quinone. The major polar lipids of strain Ran72T were phosphatidylethanolamine, four unidentified aminolipids, and two unidentified lipids. Based on our chemotaxonomic, genotypic, and phenotype characterizations, strain Ran72T was identified as representing a novel species in the genus Kaistella, for which the name Kaistella rhinocerotis sp. nov. is proposed, with the type strain Ran72T (=KACC 23136T=JCM 36038T). Based on the outcomes of our phylogenomic study, Chryseobacterium faecale should be reclassified under the genus Kaistella as Kaistella faecalis comb. nov.

Whole-genome sequencing and analysis of Chryseobacterium arthrosphaerae from Rana nigromaculata.

Chryseobacterium arthrosphaerae strain FS91703 was isolated from Rana nigromaculata in our previous study. To investigate the genomic characteristics, pathogenicity-related genes, antimicrobial resistance, and phylogenetic relationship of this strain, PacBio RS II and Illumina HiSeq 2000 platforms were used for the whole genome sequencing. The genome size of strain FS91703 was 5,435,691 bp and GC content was 37.78%. A total of 4,951 coding genes were predicted; 99 potential virulence factors homologs were identified. Analysis of antibiotic resistance genes revealed that strain FS91703 harbored 10 antibiotic resistance genes in 6 categories and 2 multidrug-resistant efflux pump genes, including adeG and farA. Strain FS91703 was sensitive to ß-lactam combination drugs, cephem, monobactam and carbapenems, intermediately resistant to phenicol, and resistant to penicillin, aminoglycosides, tetracycline, fluoroquinolones, and folate pathway inhibitors. Phylogenetic analysis revealed that strain FS91703 and C. arthrosphaerae CC-VM-7T were on the same branch of the phylogenetic tree based on 16 S rRNA; the ANI value between them was 96.99%; and the DDH values were 80.2, 72.2 and 81.6% by three default calculation formulae. These results suggested that strain FS91703 was a species of C. arthrosphaerae. Pan-genome analysis showed FS91703 had 566 unique genes compared with 13 other C. arthrosphaerae strains, and had a distant phylogenetic relationship with the other C. arthrosphaerae strains of the same branch in phylogenetic tree based on orthologous genes. The results of this study suggest that strain FS91703 is a multidrug-resistant and highly virulent bacterium, that differs from other C. arthrosphaerae strains at the genomic level. The knowledge about the genomic characteristics and antimicrobial resistance of strain FS91703 provides valuable insights into this rare species, as well as guidance for the treatment of the disease caused by FS91703 in Rana nigromaculata.

Isolation and identification of a high-efficiency hexavalent uranium adsorption strain and preliminary study of the influencing factors and adsorption mechanism.

In this study, a bacterial strain Chryseobacterium bernardetii WK-3 was isolated from the rhizosphere soil of a uranium tailings in Southern China. It can efficiently adsorb hexavalent uranium with an adsorption ratio of 92.3%. The influence of different environmental conditions on the adsorption ratio of Chryseobacterium bernardetii strain WK-3 was investigated, and the adsorption mechanism was preliminarily discussed by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). The results showed that the optimal adsorption conditions for U(VI) by Chryseobacterium bernardetii strain WK-3 were pH = 5, temperature 30 ℃, NaCl concentration 1%, and inoculation volume 10%. When the initial concentration of U was 50 ~ 150 mg/L, the adsorption capacity of Chryseobacterium bernardetii strain WK-3 to U(VI) reached the maximum and maintained the equilibrium at 44 h. SEM-EDS results showed that phosphorus in cells participates in the interaction of uranyl ions, which may indicate that phosphate was produced during cell metabolism and was further combined to form U(VI)-phosphate minerals. In summary, Chryseobacterium bernardetii strain WK-3 would be a promising alternative for environmental uranium contamination remediation.

A rare urinary tract infection of multidrug-resistant Chryseobacterium urinae sp. nov. isolated from a diabetic, non-catheterized patient.

Chryseobacterium demonstrates a diverse environmental presence and a significant pathogenic potential across various ecosystems. This clinical case showcases a rare instance of bacterial infection in a 75-year-old male with untreated diabetes and recurrent urinary tract infections (UTIs). The patient presented symptoms of abdominal pain, burning urination, fever, and an elevated eosinophil count. A subsequent urine culture identified a Chryseobacterium-related bacterium as the causative agent, exhibiting sensitivity to piperacillin/tazobactam, trimethoprim/sulfamethoxazole, and nitrofurantoin, which led to successful treatment using oral nitrofurantoin. Analysis of the 16S rRNA gene sequence of APV-1T revealed a close relationship of 98.2% similarity to Chryseobacterium gambrini strain 5-1St1aT (AM232810). Furthermore, comparative genome analysis, incorporating Average Nucleotide Identity (ANI), Digital DNA-DNA Hybridization (dDDH) values, and comprehensive phylogenetic assessments utilizing 16S rRNA gene sequences, core genes, and amino acid sequences of core proteins, highlighted the unique phylogenetic positioning of APV-1T within the Chryseobacterium genus. Distinct carbon utilization and assimilation patterns, along with major fatty acid content, set APV-1T apart from C. gambrini strain 5-1St1aT. These findings, encompassing phenotypic, genotypic, and chemotaxonomic characteristics, strongly support the proposal of a novel species named Chryseobacterium urinae sp. nov., with APV-1T designated as the type strain (= MCC 50690 = JCM 36476). Despite its successful treatment, the strain displayed resistance to multiple antibiotics. Genomic analysis further unveiled core-conserved genes, strain-specific clusters, and genes associated with antibiotic resistance and virulence. This report underscores the vital importance of elucidating susceptibility patterns of rare pathogens like Chryseobacterium, particularly in immunocompromised individuals. It advocates for further analyses to understand the functional significance of identified genes and their implications in treatment and pathogenesis.

Elucidating doxycycline biotransformation mechanism by Chryseobacterium sp. WX1: Multi-omics insights.

Doxycycline (DOX) represents a second-generation tetracycline antibiotic that persists as a challenging-to-degrade contaminant in environmental compartments. Despite its ubiquity, scant literature exists on bacteria proficient in DOX degradation. This study marked a substantial advancement in this field by isolating Chryseobacterium sp. WX1 from an activated sludge enrichment culture, showcasing its unprecedented ability to completely degrade 50 mg/L of DOX within 44 h. Throughout the degradation process, seven biotransformation products were identified, revealing a complex pathway that began with the hydroxylation of DOX, followed by a series of transformations. Employing an integrated multi-omics approach alongside in vitro heterologous expression assays, our study distinctly identified the tetX gene as a critical facilitator of DOX hydroxylation. Proteomic analyses further pinpointed the enzymes postulated to mediate the downstream modifications of DOX hydroxylation derivatives. The elucidated degradation pathway encompassed several key biological processes, such as the microbial transmembrane transport of DOX and its intermediates, the orchestration of enzyme synthesis for transformation, energy metabolism, and other gene-regulated biological directives. This study provides the first insight into the adaptive biotransformation strategies of Chryseobacterium under DOX-induced stress, highlighting the potential applications of this strain to augment DOX removal in wastewater treatment systems containing high concentrations of DOX.

Parallel evolution of alternate morphotypes of Chryseobacterium gleum during experimental evolution with Caenorhabditis elegans.

Microbial evolution within polymicrobial communities is a complex process. Here, we report within-species diversification within multispecies microbial communities during experimental evolution with the nematode Caenorhabditis elegans. We describe morphological diversity in the target species Chryseobacterium gleum, which developed a novel colony morphotype in a small number of replicate communities. Alternate morphotypes coexisted with original morphotypes in communities, as well as in single-species experiments using evolved isolates. We found that the original and alternate morphotypes differed in motility and in spatial expansion in the presence of C. elegans. This study provides insight into the emergence and maintenance of intraspecies diversity in the context of microbial communities.

Description of Chryseobacterium fluminis sp. nov., a keratinolytic bacterium isolated from a freshwater river.

A Gram-stain-negative, aerobic, rod-shaped bacterial strain, designated MMS21-Ot14T, was isolated from a freshwater river, and shown to represent a novel species of the genus Chryseobacterium on the basis of the results from a polyphasic approach. The 16S rRNA gene sequence analysis revealed that MMS21-Ot14T represented a member of the genus Chryseobacterium of the family Weeksellaceae and was closely related to Chryseobacterium hagamense RHA2-9T (97.52 % sequence similarity), Chryseobacterium gwangjuense THG A18T (97.46 %) and Chryseobacterium gregarium P 461/12T (97.27 %). The optimal growth of MMS21-Ot14T occurred at 25-30 °C, pH 6.0-7.0 and in the absence of NaCl. MMS21-Ot14T was capable of hydrolysing casein, starch, DNA, Tween 20 and tyrosine. The strain also showed keratinolytic activity with keratin azure and decolourising activity with remazol brilliant blue R (RBBR), which indicated potential ability to degrade keratin and lignin. The main polar lipids of MMS21-Ot14T were phosphatidylethanolamine, unidentified aminophospholipids, unidentified aminolipids, an unidentified phospholipid and several unidentified lipids. The predominant fatty acids of MMS21-Ot14T were iso-C15 : 0 and iso-C17 : 0 3-OH, and the major isoprenoid quinone was menaquinone 6 (MK-6). The whole genome of MMS21-Ot14T was 5 062 016 bp in length with a DNA G+C content of 37.7 %. The average nucleotide identity and digital DNA-DNA hybridisation values between MMS21-Ot14T and phylogenetically related members of the genus Chryseobacterium were well below the threshold values for species delineation. It is evident from the results of this study that MMS21-Ot14T should be classified as representing a novel species of the genus Chryseobacterium, for which the name Chryseobacterium fluminis sp. nov. (type strain, MMS21-Ot14T = KCTC 92255T = LMG 32529T) is proposed.

Uranium biomineralization by immobilized Chryseobacterium sp. strain PMSZPI cells for efficient uranium removal.

Uranium (U) contamination is hazardous to human health and the environment owing to its radiotoxicity and chemical toxicity and needs immediate attention. In this study, the immobilized biomass of Chryseobacterium sp. strain PMSZPI isolated from U enriched site, was investigated for U(VI) biomineralization in batch and column set-up. Under batch mode, the fresh or lyophilized cells successfully entrapped in calcium alginate beads demonstrated effectual U precipitation under acid and alkaline conditions. The maximum removal was detected at pH 7 wherein ∼98-99% of uranium was precipitated from 1 mM uranyl carbonate solution loading ∼350 mg U/g of biomass within 24 h in the presence of organic phosphate substrate. The resulting uranyl phosphate precipitates within immobilized biomass loaded beads were observed by SEM-EDX and TEM while the formation of U biomineral was confirmed by FTIR and XRD. Retention of phosphatase activity without any loss of uranium precipitation ability was observed for alginate beads with lyophilized biomass stored for 90 d at 4 °C. Continuous flow through experiment with PMSZPI biomass immobilized in polyacrylamide gel exhibited U loading of 0.8 g U/g of biomass at pH 7 using 1 l of 1 mM uranyl solution. This investigation established the feasibility for the application of immobilized PMSZPI biomass for field studies. ENVIRONMENTAL IMPLICATION: Uranium contamination is currently a serious environmental concern owing to anthropogenic activities and needs immediate attention. We have developed here a biotechnological method for successful uranium removal using immobilized cells of a uranium tolerant environmental bacterium, Chryseobacterium sp. strain PMSZPI isolated from U ore deposit via phosphatase enzyme mediated uranium precipitation. The ability of immobilized PMSZPI cells to precipitate U(VI) as long-term stable U phosphates under environmental conditions relevant for contaminated waters containing high concentrations of U that exerts toxicity for biological systems is explored here. The long term stability of the immobilized biomass without compromising its U removal capacity shows the relevance of the bioremediation strategy for uranium contamination proposed in this work.

The integrative and conjugative element ICECiPOL15 mediates horizontal transfer of ß-lactam resistance gene in Chryseobacterium indoltheticum POL15.

OBJECTIVES: The dissemination of antibiotic resistance genes (ARGs) from the environment, including agricultural sources, is of increasing concern. In this study, we examined the antibiotic resistance profile and genomic sequence of a strain of Chryseobacterium indoltheticum obtained from an agricultural location. METHODS: The multidrug-resistant bacterial strain POL15 was isolated from the wastewater of a livestock farm in China. Whole-genome sequencing was performed followed by bioinformatics analyses to identify integrative and conjugative elements (ICEs) and ARGs. Mating assays were performed to analyse ICE transferability. RESULTS: Whole-genome sequencing and annotation showed that the genome of POL15 encodes ARGs. Additionally, an ICE named ICECiPOL15, which carries a class C ß-lactamase-encoding gene blaAQU, was identified in the POL15 genome. Genes encoding an integrase, an excisionase, a relaxase, a type IV coupling protein and conjugative transposon proteins involved in a type IV secretion system were also identified in ICECiPOL15. Sequence alignment revealed that ICECiPOL15 might have evolved from other Chryseobacterium species. The horizontal transferability of ICECiPOL15 was demonstrated by mating experiments between C. indoltheticum POL15 and Escherichia coli DL21. CONCLUSIONS: This study represents the first characterization of a mobilizable antibiotic resistance ICE in a species of C. indoltheticum and provides evidence that C. indoltheticum strains could be important reservoirs and vehicles for ARGs on livestock farms.

First case of Chryseobacterium gallinarum bloodstream infection: a diagnostic and therapeutic challenge for an emerging pathogen.

Chryseobacterium spp. belongs to the Flavobacteriaceae family and is a rod-shaped gram-negative, glucose non-fermenting, non-motile bacterium ubiquitous in the environment. In humans, Chryseobacterium may be responsible for infections such as urinary tract infections (UTI) and ventriculitis with a pathogenic burden increasing in recent years. Chryseobacterium gallinarum was isolated for the first time in 2014 in a pharyngeal scrape sample of chicken and, until now, only one case of human UTI has been described in a pregnant 20-year-old Indian patient. Herein, we report the first case of bloodstream infection caused by C. gallinarum in a 67-year-old female burn patient, correctly identified by 16S-rRNA sequencing and successfully treated with cefepime and fosfomycin.

Genome analysis deciphered Chryseobacterium indicum is a distinct species associated with freshwater pufferfish.

A bacterium, strain PS-8T of the genus Chryseobacterium, was isolated from the skin of freshwater pufferfish (Tetraodon cutcutia). Strain PS-8T is a Gram-negative, aerobic, non-motile, and rod-shaped bacterium. Colonies appear in yellowish-orange colors. The major cellular fatty acids were C15:0 iso, C17:0 iso 3OH, C15:0 iso 3OH, and C11:0 anteiso. The predominant polar lipids were phosphatidylethanolamine and amino lipids. The genome size is 4.83 Mb. The G + C content was 35.6%. The in silico dDDH homology, ANI, and AAI were below the cutoff value, 70% and 95% to 96%, respectively, suggesting that strain PS-8T represents a defined species. The phylogenetic tree based on core and the non-recombinant genes showed the strain PS-8T clustered with Chryseobacterium gambrini DSM 18014T. Genome-wide analysis decodes several virulence factors of the genus Chryseobacterium, including genes for adherence, biofilm and stability, proliferation, resistance to immune response, and host-defense evasion system. The cladogram of the virulence genes showed a phylogenetic relationship among the Chryseobacterium species. Knowledge of the association of Chryseobacterium with freshwater pufferfish adds a new ecological niche to this bacterium.

Phenotypic and genomic characterization of a non-pathogenic Epilithonimonas ginsengisoli isolated from diseased farmed rainbow trout (Oncorhynchus mykiss) in Chile.

Flavobacterial infection associated with diseased fish is caused by multiple bacterial species within the family Flavobacteriaceae. In the present study, the Chilean isolate FP99, from the gills of a diseased, farmed rainbow trout (Oncorhynchus mykiss), was characterized using phenotypic and genomic analyses. Additionally assessed was pathogenic activity. Phylogenetic analysis based on 16S rRNA gene sequencing confirmed that isolate FP99 belonged to the genus Epilithonimonas, an average nucleotide identity value of 100% was detected with the Chilean isolate identified as Epilithonimonas sp. FP211-J200. In silico genome analysis, mechanisms for toxins production, and superantigens, adhesion, or other genes associated with virulence were not detected. However, genes encoding proteins for antibiotic resistance were found, including the chrA gene and the nucleotide sequence that encodes for multiple antibiotic resistance MarC proteins. Furthermore, the blaESP-1 gene (87.85% aminoacidic sequence identity), encoding an extended-spectrum subclass B3 metallo-ß-lactamase and conferring carbapenem-hydrolysing activity, and the tet(X) gene, which encodes a monooxygenase that catalyses the degradation of tetracycline-class antimicrobials were carried by this isolate. Phenotyping analyses also supported assignment as E. ginsengisoli. Challenge trials against healthy rainbow trout resulted in no observed pathogenic effect. Our findings identify for the first time the species E. ginsengisoli as associated with fish farming, suggesting that this isolate may be a component of the microbiota of the freshwater system. Notwithstanding, poor environmental conditions and any stressors associated with aquaculture situations or lesions caused by other pathogenic bacteria, such as F. psychrophilum, could favour the entry of E. ginsengisoli into rainbow trout.

Elizabethkingia meningoseptica Outbreak in NICU: An Observational Study on a Debilitating Neuroinfection in Neonates.

BACKGROUND: Elizabethkingia meningoseptica is an emerging nosocomial pathogen implicated in neonatal sepsis with high mortality and morbidities. However, there is very limited data regarding the characteristics as well as outcomes following this infection, particularly in developing countries. METHODS: We conducted a retrospective observational study of all infants with culture-positive Elizabethkingia sepsis as part of an outbreak, to study their clinical and epidemiological characteristics, as well as their antimicrobial susceptibility patterns, using a structured proforma from the neonatal intensive care unit database. Analysis was done using descriptive statistics and predictors of mortality and hydrocephalus were also identified. RESULTS: Of the 21 neonates enrolled, 9 (42.9%) were male, with a mean gestational age and birth weight of 31.7 ± 3.4 weeks and 1320 ± 364 g, respectively. The median (interquartile range) age of onset of illness was 7 (5-12) days. The overall mortality rate was 23.8%, and among survivors, 50% had neurologic complications requiring intervention. Vancomycin and ciprofloxacin were the most used antibiotics for treatment in our series, with a median duration of 26 (17-38) days. On univariate analysis, shock at presentation was significantly associated with increased mortality (P = 0.04) while, seizures (P = 0.04) and elevated cerebrospinal fluid protein levels (P = 0 .01) at onset of illness predicted progressive hydrocephalus in surviving neonates. CONCLUSION: E. meningoseptica sepsis is associated with high morbidity and mortality. Early diagnosis and prompt initiation of appropriate antibiotics are critical for improving survival and neurodevelopmental outcomes. Though isolation of the organism by environmental surveillance is always not possible, with proper infection control measures, the infection can be controlled.

Chryseobacterium pyrolae sp. nov., isolated from the rhizosphere soil of Pyrola calliantha H.

A novel Gram-stain-negative, aerobic, non-motile, rod-shaped bacterium, designated pc2-12T, was isolated from the rhizosphere soil of the herb Pyrola calliantha collected from arid areas of Tibet. The strain grew most vigorously with 1 % (w/v) NaCl, at pH 7.0 and at 25 °C. According to the results of 16S rRNA gene sequence analysis, pc2-12T was closely related to the members of the genus Chryseobacterium, with highest levels of sequence similarity to Chryseobacterium viscerum 687B-08T (98.42 %), Chryseobacterium oncorhynchi 701B-08T (98.11 %) and Chryseobacterium ureilyticum DSM 18017T (97.98 %). The average nucleotide identity values between pc2-12T and C. viscerum 687B-08T, C. oncorhynchi 701B-08T and C. ureilyticum DSM 18017T were 79.71, 79.49 and 79.26 %, respectively. The in silico DNA-DNA hybridisation values between pc2-12T and C. viscerum 687B-08T, C. oncorhynchi 701B-08T and C. ureilyticum DSM 18017T were 23.30, 23.00 and 22.90 %, respectively. The draft genome sequence of pc2-12T was 4.64 Mb long, with DNA G+C content of 37.0 mol%. The fatty acids contained in the cells of pc2-12T were mainly composed of iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c). The main polar lipid was phosphatidylethanolamine. MK-6 was the sole respiratory quinone. On the basis of the results of analysis of all the data described, pc2-12T is considered to represent a novel species of the genus Chryseobacterium, for which the name Chryseobacterium pyrolae sp. nov., is proposed. The type strain is pc2-12T (=GDMCC 1.3256T= JCM 35712T).

Genome features of a novel hydrocarbonoclastic Chryseobacterium oranimense strain and its comparison to bacterial oil-degraders and to other C. oranimense strains.

For the first time, we report the whole genome sequence of a hydrocarbonoclastic Chryseobacterium oranimense strain isolated from Trinidad and Tobago (COTT) and its genes involved in the biotransformation of hydrocarbons and xenobiotics through functional annotation. The assembly consisted of 11 contigs with 2,794 predicted protein-coding genes which included a diverse group of gene families involved in aliphatic and polycyclic hydrocarbon degradation. Comparative genomic analyses with 18 crude-oil degrading bacteria in addition to two C. oranimense strains not associated with oil were carried out. The data revealed important differences in terms of annotated genes involved in the hydrocarbon degradation process that may explain the molecular mechanisms of hydrocarbon and xenobiotic biotransformation. Notably, many gene families were expanded to explain COTT's competitive ability to manage habitat-specific stressors. Gene-based evidence of the metabolic potential of COTT supports the application of indigenous microbes for the remediation of polluted terrestrial environments and provides a genomic resource for improving our understanding of how to optimize these characteristics for more effective bioremediation.

Probability of outbreaks and cross-border dissemination of the emerging pathogen: a genomic survey of Elizabethkingia meningoseptica.

IMPORTANCE: Elizabethkingia meningoseptica is an emerging infectious agent associated with life-threatening infections in immunocompromised individuals. However, there are limited data available on the genomic features of E. meningoseptica. This study aims to characterize the geographical distribution, phylogenetic evolution, pathogenesis, and transmission of this bacterium. A systematic analysis of the E. meningoseptica genome revealed that a common ancestor of this bacterium existed 90 years ago. The evolutionary history showed no significant relationship with the sample source, origin, or region, despite the presence of genetic diversity. Whole genome sequencing data also demonstrated that E. meningoseptica bacteria possess inherent resistance and pathogenicity, enabling them to spread within the same hospital and even across borders. This study highlights the potential for E. meningoseptica to cause severe nosocomial outbreaks and horizontal transmission between countries worldwide. The available evidence is crucial for the development of evidence-based public health policies to prevent global outbreaks caused by emerging pathogens.

Comparative genomic analysis of Chryseobacterium species: deep insights into plant-growth-promoting and halotolerant capacities.

Members of the genus Chryseobacterium have attracted great interest as beneficial bacteria that can promote plant growth and biocontrol. Given the recent risks of climate change, it is important to develop tolerance strategies for efficient applications of plant-beneficial bacteria in saline environments. However, the genetic determinants of plant-growth-promoting and halotolerance effects in Chryseobacterium have not yet been investigated at the genomic level. Here, a comparative genomic analysis was conducted with seven Chryseobacterium species. Phylogenetic and phylogenomic analyses revealed niche-specific evolutionary distances between soil and freshwater Chryseobacterium species, consistent with differences in genomic statistics, indicating that the freshwater bacteria have smaller genome sizes and fewer genes than the soil bacteria. Phosphorus- and zinc-cycling genes (required for nutrient acquisition in plants) were universally present in all species, whereas nitrification and sulphite reduction genes (required for nitrogen- and sulphur-cycling, respectively) were distributed only in soil bacteria. A pan-genome containing 6842 gene clusters was constructed, which reflected the general features of the core, accessory and unique genomes. Halotolerant species with an accessory genome shared a Kdp potassium transporter and biosynthetic pathways for branched-chain amino acids and the carotenoid lycopene, which are associated with countermeasures against salt stress. Protein-protein interaction network analysis was used to define the genetic determinants of Chryseobacterium salivictor NBC122 that reduce salt damage in bacteria and plants. Sixteen hub genes comprised the aromatic compound degradation and Por secretion systems, which are required to cope with complex stresses associated with saline environments. Horizontal gene transfer and CRISPR-Cas analyses indicated that C. salivictor NBC122 underwent more evolutionary events when interacting with different environments. These findings provide deep insights into genomic adaptation to dynamic interactions between plant-growth-promoting Chryseobacterium and salt stress.

Mechanism of safener mefenpyr-diethyl biodegradation by a newly isolated Chryseobacterium sp. B6 from wastewater sludge and application in co-contaminated soil.

Safener mefenpyr-diethyl (MFD) was applied to cereal crops along with herbicides to improve herbicide selectivity for crops and weeds. However, the degradation mechanism of MFD in the environment remains unclear. One MFD-degrading bacterium, Chryseobacterium sp. B6, was isolated from activated sludge. According to Box-Behnken's optimal design, the degradation efficiency of MFD can reach 92% under conditions of pH 7.5, 30 °C, and a MFD concentration of 184 mg L-1. The degradation half-life experiment showed that a high concentration of MFD (300 mg L-1) inhibited the degradation ability of strain B6. Additionally, strain B6 was resistant to Ba2+, Cr3+, Li+, Zn2+, and Cu2+. The MFD degradation products of strain B6 were detected by GC/MS and its degradation pathway was proposed. MFD was first hydrolyzed by a hydrolase to an intermediate (RS)-1-(2,4-dichlorophenyl)-5-methyl-2-pyrazoline-5-carboxylic acid ethyl ester-3-carboxylic acid, and then further degraded by a decarboxylase to form the intermediate (RS)-1-(2,4-dichlorophenyl)-5-methyl-2-pyrazoline-5-carboxylic acid ethyl ester, finally, it is completely degraded by strain B6. Furthermore, strain B6 could effectively remove MFD from MFD-contaminated soil, and the half-life of MFD was also significantly reduced in MFD and Cu2+ co-contaminated soil after inoculating strain B6. To our knowledge, strain B6 was the first strain reported to degrade safener MFD, and this study provides a valuable candidate to remediate the co-contaminated soil with MFD and Cu2+.