Chryseobacterium salivictor sp. nov., a plant-growth-promoting bacterium isolated from freshwater.

A Gram-stain-negative, non-motile, rod-shaped bacterial strain, designated NBC 122T, was isolated from freshwater of the Nakdong River Republic of Korea. Growth occurred at pH 5.0-8.0 (optimum, pH 7.0), at 4-37 °C (optimum, 25 °C), and with 0-3.5% (w/v) NaCl (optimum, 1%). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain NBC 122T belongs to the genus Chryseobacterium and is most closely related to Chryseobacterium antarcticum AT1013T (97.85%). The average nucleotide identity and in silico DNA-DNA hybridization (DDH) values between strain NBC 122T and related Chryseobacterium species were 77.77-80.28 and 20.9-23.2%, respectively. The strain NBC 122T contained MK-6 as the major respiratory quinone. The major fatty acids included anteiso C15:0, iso C15:0, summed feature 9 (C17:1 iso ω9c, C16:0 10-methyl) and iso C17:0 3-OH, and the polar lipids were phosphatidylethanolamine, five unidentified aminolipids and six unidentified lipids. The DNA G + C content was 37.5 mol%. On the basis of a 16S rRNA gene phylogeny and comparative phenotypic analyses, strain NBC 122T represents a novel species in the genus Chryseobacterium, for which the name Chryseobacterium salivictor sp. nov. is proposed. The type strain is NBC122T (= KCTC 72248T = JCM 33980T).

Genomic and functional insights into the adaptation and survival of Chryseobacterium sp. strain PMSZPI in uranium enriched environment.

Metal enriched areas represent important and dynamic microbiological ecosystems. In this study, the draft genome of a uranium (U) tolerant bacterium, Chryseobacterium sp. strain PMSZPI, isolated from the subsurface soil of Domiasiat uranium ore deposit in Northeast India, was analyzed. The strain revealed a genome size of 3.8 Mb comprising of 3346 predicted protein-coding genes. The analysis indicated high abundance of genes associated with metal resistance and efflux, transporters, phosphatases, antibiotic resistance, polysaccharide synthesis, motility, protein secretion systems, oxidoreductases and DNA repair. Comparative genomics with other closely related Chryseobacterium strains led to the identification of unique inventory of genes which were of adaptive significance in PMSZPI. Consistent with the genome analysis, PMSZPI showed superior tolerance to uranium and other heavy metals. The metal exposed cells exhibited transcriptional induction of metal translocating PIB ATPases suggestive of their involvement in metal resistance. Efficient U binding (~90% of 100 µM U) and U bioprecipitation (~93-94% of 1 mM U at pH 5, 7 and 9) could be attributed as uranium tolerance strategies in PMSZPI. The strain demonstrated resistance to a large number of antibiotics which was in agreement with in silico prediction. Reduced gliding motility in the presence of cadmium and uranium, enhanced biofilm formation on uranium exposure and tolerance to 1.5 kGy of 60Co gamma radiation were perceived as adaptive responses in PMSZPI. Overall, the positive correlation observed between uranium/metal tolerance abilities predicted using genome analysis and the functional characterization reinforced the multifaceted adaptation strategies employed by PMSZPI for its survival in the soil of uranium ore deposit comprising of high concentrations of uranium and other heavy metals.

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.

Identification and characterization of a novel indigenous algicidal bacterium Chryseobacterium species against Microcystis aeruginosa.

Harmful Microcystis aeruginosa blooms occurred frequently in many eutrophic lakes and rivers with resultant serious global environmental consequences. Algicidal bacteria may play an important role in inhibiting the growth of Microcystis aeruginosa and are considered as an effective method for preventing the appearance of blooms. In order to counteract the harmful effects of Microcystis aeruginosa, a critical step is to identify, isolate and characterize indigenous algicidal bacteria. This study aimed to isolate a novel indigenous algicidal bacterium identified as Chryseobacterium species based upon its 16S rDNA sequence analysis, and determine whether this bacterium was effective in lysing Microcystis aeruginosa FACHB 905. The influence of environmental factors including temperature, pH, quantity of Chryseobacterium species as well as Microcystis aeruginosa concentration were examined with respect to algae-lysing properties of this bacterial strain. Data demonstrated that the highest algae-lysing activity of 80% against Microcystis aeruginosa FACHB 905 occurred within 72 hr. In addition, the algae-lysing activities of Chryseobacterium species cells were significantly higher than those of cell-free supernatant. In conclusion, data showed the algicidal bacterium Chryseobacterium species exhibited potent Microcystis aeruginosa-lysing activities and attacked Microcystis aeruginosa directly suggesting this algicidal bacterium may be potentially useful for reducing the number of harmful Microcystis aeruginosa blooms.

The golden death bacillus Chryseobacterium nematophagum is a novel matrix digesting pathogen of nematodes.

BACKGROUND: Nematodes represent important pathogens of humans and farmed animals and cause significant health and economic impacts. The control of nematodes is primarily carried out by applying a limited number of anthelmintic compounds, for which there is now widespread resistance being reported. There is a current unmet need to develop novel control measures including the identification and characterisation of natural pathogens of nematodes. RESULTS: Nematode killing bacilli were isolated from a rotten fruit in association with wild free-living nematodes. These bacteria belong to the Chryseobacterium genus (golden bacteria) and represent a new species named Chryseobacterium nematophagum. These bacilli are oxidase-positive, flexirubin-pigmented, gram-negative rods that exhibit gelatinase activity. Caenorhabditis elegans are attracted to and eat these bacteria. Within 3 h of ingestion, however, the bacilli have degraded the anterior pharyngeal chitinous lining and entered the body cavity, ultimately killing the host. Within 24 h, the internal contents of the worms are digested followed by the final digestion of the remaining cuticle over a 2-3-day period. These bacteria will also infect and kill bacterivorous free-living (L1-L3) stages of all tested parasitic nematodes including the important veterinary Trichostrongylids such as Haemonchus contortus and Ostertagia ostertagi. The bacteria exhibit potent collagen-digesting properties, and genome sequencing has identified novel metalloprotease, collagenase and chitinase enzymes representing potential virulence factors. CONCLUSIONS: Chryseobacterium nematophagum is a newly discovered pathogen of nematodes that rapidly kills environmental stages of a wide range of key nematode parasites. These bacilli exhibit a unique invasion process, entering the body via the anterior pharynx through the specific degradation of extracellular matrices. This bacterial pathogen represents a prospective biological control agent for important nematode parasites.

Functional Characterization of Probiotic Potential of Novel Pigmented Bacterial Strains for Aquaculture Applications.

The bioprospecting proficient of novel pigmented probiotic strains with respect to aquaculture industry was unexplored hitherto. In this study, we investigated the probiotic potential of novel pigmented bacterial strains isolated from the indigenous soil sediments in their vicinal habitats, which were screened for their antimicrobial activity against aquatic pathogens using agar well diffusion assay. The strains namely Exiguobacterium acetylicum (S01), Aeromonas veronii (V03), and Chryseobacterium joostei (V04) were phenotypically identified and confirmed by 16S rRNA gene sequence analysis. Further characterization revealed that strains S01 and V03 survive relatively in lower pH and higher bile salt concentrations and possess good adherence ability and broad-spectrum antibiotic susceptibility. The isolate S01 exhibited the higher adhesion ability to hydrocarbons (82%) and mannose-specific adhesion (msa) gene expression. Additionally, the probiotic effects were evaluated in Artemia nauplii fed with algae supplemented with S01, V03, and V04 strains (2.7 × 107 cfu/mL) for 3 days under axenic environment. We observed a significant increase (p < 0.05) in the survival rate of Artemia nauplii treated with S01 (83 ± 5%) and V03 (55 ± 5%), whereas the survival rate was only 30 ± 0% in the untreated group. Moreover, the individual length (IL) was increased in treated group S01 (156.7 ± 2.2 µm), V03 (146.1 ± 3.4 µm), and V04 (134.4 ± 2.5 µm) compared with untreated group (116.0 ± 4.8 µm). Our results revealed that E. acetylicum S01 exhibits desirable functional probiotic attributes compared to A. veronii and C. joostei and it would be a promising probiotic strain, which can be efficiently used in the aquaculture applications.

Characterizing bacterial communities in paper production-troublemakers revealed.

Biofilm formation is a major cause of reduced paper quality and increased down time during paper manufacturing. This study uses Illumina next-generation sequencing to identify the microbial populations causing quality issues due to their presence in biofilms and slimes. The paper defects investigated contained traces of the films and/or slime of mainly two genera, Tepidimonas and Chryseobacterium. The Tepidimonas spp. found contributed on average 68% to the total bacterial population. Both genera have been described previously to be associated with biofilms in paper mills. There was indication that Tepidimonas spp. were present as compact biofilm in the head box of one paper machine and was filtered out by the paper web during production. On the other hand Tepidimonas spp. were also present to a large extent in the press and white waters of two nonproblematic paper machines. Therefore, the mere presence of a known biofilm producer alone is not sufficient to cause slimes and therefore paper defects and other critical factors are additionally at play. For instance, we identified Acidovorax sp., which is an early colonizer of paper machines, exhibiting the ability to form extracellular DNA matrices for attachment and biofilm formation.

Unforeseeable presentation of Chryseobacterium indologenes infection in a paediatric patient.

BACKGROUND: We report for the first time a case of community acquired Chryseobacterium indologenes soft tissue infection in an immunocompetent patient. CASE PRESENTATION: A 11 year female child, from South-Asia of Indian origin presented with fever, pain and swelling in right leg for 3 days with no significant past history. Incision and drainage was done and pus was sent for culture and sensitivity. Radiological investigation showed subtle irregular soft tissue density. Pus culture grew multidrug resistant C. indologenes. CONCLUSION: Though of low pathogenicity, our case emphasises its unpredictable nature and the need to determine minimum inhibitory concentration breakpoints for therapy.

Assessment of biofilm formation of E. meningoseptica, D. acidovorans, and S. maltophilia in lens cases and their growth on recovery media.

PURPOSE: Bacterial biofilm formation in contact lens cases is a risk factor in the development of both microbial and infiltrative keratitis. This investigation evaluated three emerging pathogens: Stenotrophomonas maltophilia, Elizabethkingia meningoseptica, and Delftia acidovorans for biofilm formation and metabolic activity in lens cases. Also, growth of these bacteria on different media was assessed to optimize recovery conditions. METHODS: The three bacteria were incubated in lens cases with different concentrations of tryptic soy broth. Biofilm formation was evaluated by measuring metabolic activity using MTT and enumerating the number of viable bacteria. To determine the optimal recovery media, dilutions of these microorganisms were plated on six different media. The number of colony forming units (CFU) was recorded after 48, 72, and 96 h of incubation at 32°C and 37°C for S. maltophilia, and at 37°C for E. meningoseptica and D. acidovorans. RESULTS: All three microorganisms established biofilms in the lens cases, with significant numbers of CFU recovered. Biofilms of S. maltophilia and E. meningoseptica were metabolically active. Significant reduction in metabolic activity and number of viable S. maltophilia occurred when the incubation temperature was raised from 32°C to 37°C (p<0.05). The metabolic activity of the biofilms increased with greater organic load present. The highest percent recovery for all three organisms was given by Columbia blood agar, followed by chocolate. CONCLUSION: Based on the results, the presence of the three emerging pathogens present in lens cases and from corneal isolates can be accurately determined if proper growth media and incubation temperatures are utilized.

Synergistic algicidal effect and mechanism of two diketopiperazines produced by Chryseobacterium sp. strain GLY-1106 on the harmful bloom-forming Microcystis aeruginosa.

A potent algicidal bacterium isolated from Lake Taihu, Chryseobacterium sp. strain GLY-1106, produces two algicidal compounds: 1106-A (cyclo(4-OH-Pro-Leu)) and 1106-B (cyclo(Pro-Leu)). Both diketopiperazines showed strong algicidal activities against Microcystis aeruginosa, the dominant bloom-forming cyanobacterium in Lake Taihu. Interestingly, these two algicidal compounds functioned synergistically. Compared with individual treatment, combined treatment with cyclo(4-OH-Pro-Leu) and cyclo(Pro-Leu) significantly enhanced algicidal activity, accelerated the increase in intracellular reactive oxygen species (ROS) levels in M. aeruginosa, and further decreased the activities of antioxidases, effective quantum yield and maximal electron transport rate of M. aeruginosa. The results also showed that the algicidal characteristics of cyclo(4-OH-Pro-Leu) are distinct from those of cyclo(Pro-Leu). Cyclo(4-OH-Pro-Leu) mainly interrupted the flux of electron transport in the cyanobacterial photosynthetic system, whereas cyclo(Pro-Leu) mainly inhibited the activity of cyanobacterial intracellular antioxidases. A possible algicidal mechanism for the synergism between cyclo(4-OH-Pro-Leu) and cyclo(Pro-Leu) is proposed, which is in accordance with their distinct algicidal characteristics in individual and combined treatment. These findings suggest that synergism between algicidal compounds might be used as an effective strategy for the future control of Microcystis blooms.

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.

[Comparative characteristics of free-living ultramicroscopical bacteria obtained from extremal biotopes].

We isolated 50 strains of free-living ultrasmall bacteria with a cell volume that varies from 0.02 to 1.3 microm3 from a range of extremal natural biotopes, namely permafrost soils, oil slime, soils, lake silt, thermal swamp moss, and the skin integuments of the clawed frog, Xenopus laevis. Of them, 15 isolates, characterized by a cell size of less than 0.1 microm3 and a genome size from 1.5 to 2.4 Mb, were subsumed to ultramicrobacteria belonging to different philogenetic groups (Alphaproteobacteria, Bacteroidetes, Actinobacteria) and genera (Kaistia, Chryseobacterium, Microbacterium, Leucobacter, Leifsonia, and Agrococcus) of the Bacteria domain. They are free-living mesophilic heterotrophic aerobic bacteria. The representatives of Kaistia and Chryseobacterium genera were capable of facultative parasitism on other species of chemo-organotrophic bacteria and cyanobacteria. The ultramicrobacteria differed in their morpholgy, cell ultrastructural organization, and physiological and biochemical features. According to the fine structure of their cell walls, the isolates were subdivided into two groups, namely Gram-positive and Gram-negative forms.

Chryseobacterium limigenitum sp. nov., isolated from dehydrated sludge.

An intense yellow pigmented strain (SUR2(T)) isolated from dehydrated activated sludge was studied in detail to clarify its taxonomic assignment. Cells of the isolate showed a rod-shaped morphology and stained Gram-negative. Comparative 16S rRNA gene sequence analysis revealed highest similarities to the type strains of Chryseobacterium polytrichastri YG4-6(T) (98.6 %), Chryseobacterium aahli T68F(T) (97.9 %), Chryseobacterium daeguense K105(T) and Chryseobacterium gregarium DSM 79109(T) (both 97.4 %). 16S rRNA gene-sequence similarities to all other Chryseobacterium species were below 97.3 %. The fatty acid analysis of strain SUR2(T) revealed a Chryseobacterium typical profile composed mainly of the fatty acids C15:0 iso, C15:0 iso 2-OH, C17:1 iso ω9c, and C17:0 iso 3-OH. DNA-DNA hybridizations with the type strains of C. polytrichastri, C. aahli, C. daeguense and C. gregarium resulted in values below 70 %. Differentiating biochemical and chemotaxonomic properties showed differences to the most closely related species and suggest that the isolate SUR2(T) represents a novel species, for which the name Chryseobacterium limigenitum sp. nov. (type strain SUR2(T) = ZIM B1019(T) = CCM 8594(T) = LMG 28734(T)) is proposed.

Chryseobacterium profundimaris sp. nov., a new member of the family Flavobacteriaceae isolated from deep-sea sediment.

A Gram-stain negative, strictly aerobic, rod-shaped, non-motile bacterium, designated strain DY46(T), was isolated from Atlantic Ocean sediment. The isolate was found to grow in medium containing 0-3.0 % (w/v) NaCl (optimally at 0-1.0 %), at 4-37 °C and pH 5.0-8.0. Chemotaxonomic analysis detected MK-6 as the sole isoprenoid quinone. The major fatty acids were identified iso-C15:0, iso-C17:0 3-OH, iso-C17:1 ω9c and summed feature 3 (comprising iso-C15:0 2-OH and/or C16:1 ω7c). The DNA G + C content was determined to be 40.7 mol %. Phylogenetic analyses based on the 16S rRNA gene sequence indicated that strain DY46(T) falls within the cluster comprising Chryseobacterium species. The levels of 16S rRNA gene sequence similarity between strain DY46(T) and the type strains of the Chryseobacterium species with validly published names ranged from 92.4 to 99.1 %, the high values (>97 %) being with Chryseobacterium takakiae A1-2(T) (99.1 %), C. taiwanense BCRC 17412(T) (98.0 %), C. taeanense PHA3-4(T) (97.3 %), C. hispalense DSM 25574(T) (97.3 %), C. camelliae THG C4-1(T) (97.2 %), C. gregarium DSM 19109(T) (97.1 %) and C. wanjuense R2A10-2(T) (97.0 %). The DNA-DNA relatedness values between strain DY46(T) and the type strains of the above closely related species were 47, 57, 24, 34, 6, 40 and 21 %, respectively. On the basis of phenotypic and genotypic characteristics, strain DY46(T) represents a novel member within the genus Chryseobacterium, for which the name Chryseobacterium profundimaris is proposed. The type strain is DY46(T) (=CGMCC 1.12663(T) = JCM 19801(T)).

Chryseobacterium rhizoplanae sp. nov., isolated from the rhizoplane environment.

A slightly yellow pigmented strain (JM-534(T)) isolated from the rhizoplane of a field-grown Zea mays plant was investigated using a polyphasic approach for its taxonomic allocation. Cells of the isolate were observed to be rod-shaped and to stain Gram-negative. Comparative 16S rRNA gene sequence analysis showed that the isolate had the highest sequence similarities to Chryseobacterium lactis (98.9 %), Chryseobacterium joostei and Chryseobacterium indologenes (both 98.7 %), and Chryseobacterium viscerum (98.6 %). Sequence similarities to all other Chryseobacterium species were 98.5 % or below. The fatty acid analysis of the strain resulted in a Chryseobacterium typical pattern consisting mainly of the fatty acids C15:0 iso, C15:0 iso 2-OH, C17:1 iso ω9c, and C17:0 iso 3-OH. DNA-DNA hybridizations with the type strains of C. lactis, C. joostei, C. viscerum and C. indologenes resulted in values below 70 %. Genomic fingerprinting showed that the isolate was very different to the type strains of these species. Differentiating biochemical and chemotaxonomic properties showed that the isolate JM-534(T) represents a novel species, for which the name Chryseobacterium rhizoplanae sp. nov. (type strain JM-534(T) = LMG 28481(T) = CCM 8544(T) = CIP 110828(T)) is proposed.

Identification, epidemiological relatedness, and biofilm formation of clinical Chryseobacterium indologenes isolates from central Taiwan.

BACKGROUND: The clinical impact of Chryseobacterium indologenes infection is increasing; nevertheless, most studies had been conducted in northern Taiwan, but rarely in central Taiwan. METHODS: Using 16S rRNA gene sequencing, 34 isolates of C. indologenes were identified at the Central Region Hospital Alliance between 2007 and 2011. Vitek 2 and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) methods were compared for the feasibility to identify this bacterium. Drug susceptibility test, biofilm formation, and pulsed-field gel electrophoresis (PFGE) were also performed. RESULTS: All isolates were collected from hospitalized patients with an average age of 70.8 ± 18.5 years. The most prevalent sample was urine (50.0%), followed by sputum (32.4%). The accuracy rate of species-level identification reached 94.1% using the Vitek 2 method and 85.3% using the MALDI-TOF MS method. All of the isolates were resistant to gentamicin, amikacin, ceftriaxone, chloramphenicol, colistin, and imipenem, but completely susceptible to minocycline. While analyzing biofilm-forming ability, 38.2% (13/34) of C. indologenes isolates displayed a positive phenotype using the Luria-Bertani (LB) medium. However, 80.0% (4/5) of invasive isolates were biofilm producers. Based on PFGE analysis, several clusters were found, and the possible intrahospital spread of this bacterium in this area could not be excluded. CONCLUSION: Both Vitek 2 and MALDI-TOF MS methods showed good ability in the determination of C. indologenes. Among the examined drugs, minocycline was the most potent one. As many as 38.2% C. indologenes isolates showed biofilm-forming ability. PFGE analyses revealed the possible intrahospital transmission of this bacterium in central Taiwan.

Chryseobacterium indologenes in a woman with acute leukemia in Senegal: a case report.

INTRODUCTION: This report documents a rare case of Chryseobacterium indologenes urinary tract infection in Senegal. Chryseobacterium indologenes is an uncommon human pathogen reported in hospital outbreaks in Taiwan and there have been some sporadic cases reported in Europe and in the USA mainly from immune-suppressed patients. CASE PRESENTATION: This case report describes a 42-year-old woman of Wolofa ethnicity who was hospitalized in our Department of Internal Medicine in a Senegalese university teaching hospital, with acute leukemia who died of severe sepsis 10 days following her hospitalization. A strain of Chryseobacterium indologenes isolated from her urine sample was resistant to several beta-lactams including ampicillin (minimum inhibitory concentrations ≥ 256 µg/mL), cefotaxime (minimum inhibitory concentrations 32 µg/mL) and imipenem (minimum inhibitory concentrations ≥ 32 µg/mL), whereas it was susceptible to piperacillin (minimum inhibitory concentrations 16 µg/mL), cefepime (minimum inhibitory concentrations 4 µg/mL), ceftazidime (minimum inhibitory concentrations 4 µg/mL), trimethoprim-sulfamethoxazole (minimum inhibitory concentrations ≤ 0.25 µg/mL) and all tested quinolones including nalidixic acid (minimum inhibitory concentrations ≤ 2 µg/mL). CONCLUSIONS: Chryseobacterium indologenes although uncommon, is an important pathogen causing infection in hospitalized patients. The management of this infection needs better identification, drug susceptibility testing and monitoring of immunosuppressed patients with long hospitalizations.

Identification, characterization, and biofilm formation of clinical Chryseobacterium gleum isolates.

Chryseobacterium gleum is not commonly isolated from clinical source(s). Using 16S rRNA gene sequencing, we identified 15 C. gleum isolates from the Central Region Hospital Alliance, Taiwan, which were all misidentified: 14 as Chryseobacterium indologenes and 1 as Elizabethkingia meningoseptica using the Vitek 2 GN card. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry, a rapid and clinically applicable method, was evaluated for the identification of C. gleum, and the rate of species or probable species level identification reached 13.3% and 86.6%, respectively. Using pulsed-field gel electrophoresis analysis, all C. gleum isolates from central Taiwan were found to be epidemiologically unrelated. The most prevalent sample was urine (35.7%, 5/14), followed by sputum (28.6%, 4/14), whereas 1 isolate was from an unknown source. All of the isolates were susceptible to minocycline, 93.3% susceptible to trimethoprim/sulfamethoxazole, but were completely or highly resistant to the other drugs examined. Biofilm-forming ability was observed in 40.0% (6/15) isolates using the Luria-Bertani broth. To the best of our knowledge, this is the first focusing on exploring clinical C. gleum isolates.

Chryseobacterium yeoncheonense sp. nov., with ginsenoside converting activity isolated from soil of a ginseng field.

A Gram-staining negative, aerobic, non-motile, non-flagellate, yellow-pigmented, rod-shaped bacterial strain, designated strain DCY67(T), was isolated from ginseng field in Republic of Korea. Strain DCY67(T) contained ß-glucosidase activity which converts ginsenoside Rb1 to compound K. Optimum growth of DCY67(T) occurred at 30 °C and pH 6.0-6.5. Analysis of the 16S rRNA gene sequences revealed that strain DCY67(T) belonged to the family Flavobacteriaceae and was most closely related to Chryseobacterium ginsenosidimutans THG 15(T) (97.5 %). The genomic DNA G+C content was 36.1 mol%. The predominant quinones were MK-6 (90.9 %) and MK-7 (9.15 %). The major fatty acids were iso-C15:0, summed feature 3 (containing C16:1 ω7c and/or C16:1 ω6c) and iso-C17:0 3-OH. On the basis of these phenotypic, genotypic and chemotaxonomic studies, strain DCY67(T) represents a novel species of the genus Chryseobacterium, for which, name Chryseobacterium yeoncheonense sp. nov. proposed the type strain is DCY67(T) (=KCTC 32090(T) = JCM 18516(T)).

16S rRNA gene-based identification of Elizabethkingia meningoseptica (Flavobacteriales: Flavobacteriaceae) as a dominant midgut bacterium of the Asian malaria vector Anopheles stephensi (Dipteria: Culicidae) with antimicrobial activities.

Following their transmission from the human to the mosquito with the bloodmeal, malaria parasites have to persevere in the mosquito midgut for approximately 1 d. During this period the parasites are highly vulnerable to factors of the mosquito midgut, including bacteria. We here aimed at determining the microbial diversity of gut bacteria of the Asian malaria vector Anopheles stephensi (Liston) during development and under different feeding regimes, including feeds on malaria parasite-infected blood. 16S rRNA and denaturing gradient gel electrophoresis analyses demonstrated an increasing reduction in the microbial diversity during mosquito development from egg to adult and identified the gram-negative bacterium Elizabethkingia meningoseptica King as the dominant species in the midgut of lab-reared male and female mosquitoes. E. meningoseptica is transmitted between generations and its predominance in the mosquito midgut was not altered by diet, when the gut microbiota was compared between sugar-fed and blood-fed female mosquitoes. Furthermore, feeds on blood infected with malaria parasites did not impact the presence of E. meningoseptica in the gut. Extracts from cultured E. meningoseptica were active against gram-positive and negative bacteria and yeast and against the blood and gametocyte transmission stages of the malaria parasite Plasmodium falciparum Welch. The antimicrobial and antiplasmodial activities of E. meningoseptica may account for its dominance in the midgut of the malaria vector.