Polyphasic study of Chryseobacterium strains isolated from diseased aquatic animals

A Duplex PCR Assay for Rapid Detection of Klebsiella pneumoniae and Chryseobacterium in Large Yellow Croaker Fish

Both Klebsiella pneumoniae and Chryseobacterium cause an increasing number of diseases in fish, resulting in great economic losses in aquaculture. In addition, the disease infected with Klebsiella pneumoniae or Chryseobacterium exhibited the similar clinical symptoms in aquatic animals. However, there is no effective means for the simultaneous detection of co-infection and discrimination them for these two pathogens. Here, we developed a duplex polymerase chain reaction (PCR) method based on the outer membrane protein A (ompA) gene of Klebsiella pneumoniae and Chryseobacterium. The specificity and validity of the designed primers were confirmed experimentally using simplex PCR. The expected amplicons for Klebsiella pneumoniae and Chryseobacterium had a size of 663 and 1404 bp, respectively. The optimal condition for duplex PCR were determined to encompass a primer concentration of 0.5 μM and annealing temperature of 57°C. This method was analytical specific with no amplification being observed from the genomic DNA of Escherichia coli, Vibrio harveyi, Pseudomonas plecoglossicida, Aeromonas hydrophila and Acinetobacter johnsonii. The limit of detection was estimated to be 20 fg of genomic DNA for Chryseobacterium and 200 fg for Klebsiella pneumoniae, or 100 colony-forming units (CFU) of bacterial cells in both cases. The duplex PCR was capable of simultaneously amplifying target fragments from genomic DNA extracted from the bacteria and fish liver. For practical validation of the method, 20 diseased fish were collected from farms, among which 4 samples were PCR-positive for Klebsiella pneumoniae and Chryseobacterium. The duplex PCR method developed here is time-saving, specific, convenient, and may prove to be an invaluable tool for molecular detection and epidemiological investigation of Klebsiella pneumoniae and Chryseobacterium in the field of aquaculture.

Analyzing the Interaction between Tetrahymena pyriformis and Bacteria under Different Physicochemical Conditions When Infecting Guppy Using the eDNA Method

In the aquaculture system of ornamental fish, the interaction between bacterial microbiota and ciliate protozoa can prevent or promote disease outbreaks, and different physicochemical conditions will affect the relationships between them. We investigated the interaction between bacterial microbiota and the parasite Tetrahymena pyriformis when infecting Poecilia reticulata (guppy) under different physicochemical conditions. The abundance of T. pyriformis in water, the relative abundance of bacterial species, and histopathological observation were studied or monitored using environmental DNA (eDNA) extraction technology, the qPCR method, and 16s rRNA sequencing, respectively. The morphological identification and phylogenetic analysis of T. pyriformis were carried out. The infected guppy tissue was also stained by the hematoxylin and eosin methods. The results showed: (1) the bacterial communities of water samples were mainly composed of species assigned to Proteobacteria and Bacteroidetes, and Tabrizicola and Puniceicoccaceae were positively correlated with fish mortality, T. pyriformis abundance, and temperature. (2) Arcicella and Methyloversatilis universalis with different correlations between ciliates appeared in different treatment groups, the result of which proved that environmental factors affected the interaction between bacteria and T. pyriformis. (3) Lower temperatures and a higher pH were more beneficial for preventing disease outbreaks.

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.

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.

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.

A review of bacterial disease outbreaks in rainbow trout (Oncorhynchus mykiss) reported from 2010 to 2022

Outbreaks of bacterial infections in aquaculture have emerged as significant threats to the sustainable production of rainbow trout (Oncorhynchus mykiss) worldwide. Understanding the dynamics of these outbreaks and the bacteria involved is crucial for implementing effective management strategies. This comprehensive review presents an update on outbreaks of bacteria isolated from rainbow trout reported between 2010 and 2022. A systematic literature survey was conducted to identify relevant studies reporting bacterial outbreaks in rainbow trout during the specified time frame. More than 150 published studies in PubMed, Web of Science, Scopus, Google Scholar and relevant databases met the inclusion criteria, encompassing diverse geographical regions and aquaculture systems. The main bacterial pathogens implicated in the outbreaks belong to both gram-negative, namely Chryseobacterium, Citrobacter, Deefgea Flavobacterium, Janthinobacterium, Plesiomonas, Pseudomonas, Shewanella, and gram-positive genera, including Lactococcus and Weissella, and comprise 36 new emerging species that are presented by means of pathogenicity and disturbance worldwide. We highlight the main characteristics of species to shed light on potential challenges in treatment strategies. Moreover, we investigate the role of various risk factors in the outbreaks, such as environmental conditions, fish density, water quality, and stressors that potentially cause outbreaks of these species. Insights into the temporal and spatial patterns of bacterial outbreaks in rainbow trout aquaculture are provided. Furthermore, the implications of these findings for developing sustainable and targeted disease prevention and control measures are discussed. The presented study serves as a comprehensive update on the state of bacterial outbreaks in rainbow trout aquaculture, emphasizing the importance of continued surveillance and research to sustain the health and productivity of this economically valuable species.

Genotypic and phenotypic analysis of Elizabethkingia meningoseptica in bullfrog Rana catesbeiana isolated in Taiwan

Elizabethkingia meningoseptica is a hazardous bacterium for agriculture production and human health. The present study identified E. meningoseptica from the bullfrog, human and reference strain BCRC 10677 by API 20NE, 50S ribosome protein L27 sequencing and pulse field gel electrophoresis to differentiate isolates of E. meningoseptica from aquatic animals and humans. All isolates from bullfrogs and humans were identified as E. meningoseptica by DNA sequencing with 98.8%-100% sequence identity. E. meningoseptica displayed significant genetic diversity when analysed using pulsed-field gel electrophoresis (PFGE). There were six distinct pulsotypes, including one pulsotype found in bullfrog isolates and five pulsotypes found in human isolates. However, E. meningoseptica from bullfrog exhibited one genotype only by PFGE. Overall, molecular epidemiological analysis of PFGE results indicated that the frog E. meningoseptica outbreaks in Taiwan were produced by genetically identical clones. The bullfrog isolates were not genetically related to other E. meningoseptica from human and reference isolates. This research provided the first comparisons of biochemical characteristics and genetic differences of E. meningoseptica from human and bullfrog isolates.

Kaistella polysaccharea sp. nov., isolated from Antarctic intertidal sediment produces a novel extracellular polymeric substance

An exopolysaccharide-producing bacterial strain GW4-15T, belonging to the genus Kaistella, was isolated from intertidal sediment from King George Island, Antarctic. The strain was Gram-stain-negative, aerobic, rod-shaped, non-motile and yellow-pigmented. The strain was able to grow in the presence of 0-2 % (w/v) NaCl (optimum, 0 %), at 4-30 °C (optimum, 20-28 °C) and at pH 5.0-10.0 (optimum, pH 8.0). A phylogenetic tree based on 16S rRNA gene sequences showed that strain GW4-15T formed a lineage within the genus Kaistella with the closest phylogenetic neighbours Kaistella carnis NCTC 13525T (98.3 %), Kaistella gelatinilytica G5-32T (97.7 %), Kaistella antarctica LMG 24720T (97.4 %) and Kaistella yonginensis HMD1043T (96.9 %). Digital DNA-DNA hybridization values of strain GW4-15T with K. carnis NCTC 13525T, K. antarctica LMG 24720T, K. gelatinilytica G5-32T and K. yonginensis HMD1043T were 22.8, 22.0, 21.7 and 21.6 %, respectively. The average nucleotide identity values between strain GW4-15T and K. carnis NCTC 13525T , K. antarctica LMG 24720T, K. gelatinilytica G5-32T and K. yonginensis HMD1043T were 79.3, 78.6, 77.5 and 77.2 %, respectively. The G+C content of the genome was 36.2 mol%. The major phospholipids were phosphatidylethanolamine and aminophospholipid. The predominant menaquinone was MK-6. The major fatty acids were anteiso-C15 : 0 (28.7 %), iso-C16 : 0 3-OH (15.7 %), iso-C16 : 0 H (10.0 %), iso-C16 : 0 (5.4 %), summed feature 9 (comprising iso-C17 : 1  ω9c and/or 10-methyl C16 : 0; 5.2 %) and iso-C15 : 0 (5.1 %). The monosaccharide composition of the new type of extracellular polymeric of GW4-15T was Glc, GalN, GlcN, Rha, Man and Gal with a molar ratio of 3.14 : 3.83 : 8.38 : 5.16 : 1 : 2.82. Based on phenotypic, phylogenetic and genotypic data, a novel species, Kaistella polysaccharea sp. nov., is proposed with the type strain GW4-15T (=CGMCC 1.19368T=KCTC 92753T).

Pathological analysis and antimicrobial susceptibility of Chryseobacterium balustinum RTFCP 298 isolated from diseased rainbow trout, Oncorhynchus mykiss

In this study, six isolates of Chryseobacterium balustinum were characterized from diseased rainbow trout fingerlings. The virulence characteristics, pathogenicity, and antimicrobial susceptibility pattern of these isolates were investigated. The bacterium showed positive results for catalase, cytochrome oxidase, and aesculin hydrolysis, while negative results were obtained for DNase, gelatinase, methyl red, Voges-Proskauer's reaction, Simon citrate, Hydrogen sulphide, and starch hydrolysis. Amino acid metabolism analysis revealed the inability to metabolize arginine, lysine, and ornithine decarboxylase. Molecular characterization (16S rRNA) and phylogenetic analysis revealed the test isolates as C. balustinum, closely related to strain WLT (99.85% similarity) and C. balustinum P-27 (99.77%). Virulence assay indicated haemolytic activity and biofilm formation by the test bacterium. The challenge test confirmed moderate pathogenicity in rainbow trout and established Koch's postulates. The clinical manifestations of infection included fin erosion, eye and body surface haemorrhage, exophthalmia, and organ liquefaction. The minimum inhibitory concentrations of various antimicrobials ranged from 1 to > 256 µg mL-1. The novel synthetic antimicrobial peptides exhibited MICs of 8 to > 256 µg mL-1, suggesting a potential control method. These findings suggest that C. balustinum is an opportunistic pathogen with moderate pathogenicity in rainbow trout. Further research on the host-pathogen relationship is necessary to understand virulence characteristics and pathogenicity in aquaculture.

Chryseobacterium oryctis sp. nov., isolated from the gut of the beetle Oryctes rhinoceros, and Chryseobacterium kimseyorum sp. nov., isolated from a stick insect rearing cage

Two strains of Chryseobacterium identified from different experiments are proposed to represent new species. Strain WLa1L2M3T was isolated from the digestive tract of an Oryctes rhinoceros beetle larva. Strain 09-1422T was isolated from a cage housing the stick insect Eurycantha calcarata. Sequence analysis of the 16S rRNA and rpoB genes found both strains to be similar but not identical to other Chryseobacterium species. Whole-genome sequencing suggested the isolates represent new species, with average nucleotide identity values ranging from 74.6 to 80.5 %. Genome-to-genome distance calculations produced values below 25.3 %, and digital DNA-DNA hybridization values were 13.7-29.9 %, all suggesting they are distinct species. The genomic DNA G+C content of WLa1L2M3T is approximately 32.53 %, and of 09-1422T is approximately 35.89 %. The predominant cellular fatty acids of strain WLa1L2M3T are C15 : 0 iso, summed feature 9 (C16 : 0 10OH or C17 : 1 iso ω6c), C17 : 0 iso 3OH, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), C15 : 0 iso 3OH, C15 : 0 anteiso and C13 : 0 iso, and those of strain 09-1422T are C15 : 0 iso, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), C17 : 0 iso 3OH, C15 : 0 anteiso, C15 : 0 iso 3OH, C16 : 1 ω7c, C17 : 0 2OH and C18 : 0. In addition, physiological and biochemical tests revealed phenotypic differences from related Chryseobacterium type strains. These cumulative data indicate that the two strains represent novel species of the genus Chryseobacterium for which the names Chryseobacterium oryctis sp. nov. and Chryseobacterium kimseyorum sp. nov. are proposed with WLa1L2M3T (=BCRC 81350T=JCM 35215T=CIP 112035T) and 09-1422T (=UCDFST 09-1422T=BCRC 81359T=CIP 112165T), as type strains, respectively.

Atypical flavobacteria recovered from diseased fish in the Western United States

Flavobacterial diseases, caused by bacteria in the order Flavobacteriales, are responsible for devastating losses in farmed and wild fish populations worldwide. The genera Flavobacterium (Family Flavobacteriaceae) and Chryseobacterium (Weeksellaceae) encompass the most well-known agents of fish disease in the order, but the full extent of piscine-pathogenic species within these diverse groups is unresolved, and likely underappreciated. To identify emerging agents of flavobacterial disease in US aquaculture, 183 presumptive Flavobacterium and Chryseobacterium isolates were collected from clinically affected fish representing 19 host types, from across six western states. Isolates were characterized by 16S rRNA gene sequencing and phylogenetic analysis using the gyrB gene. Antimicrobial susceptibility profiles were compared between representatives from each major phylogenetic clade. Of the isolates, 52 were identified as Chryseobacterium species and 131 as Flavobacterium. The majority of Chryseobacterium isolates fell into six clades (A-F) consisting of ≥ 5 fish isolates with ≥ 70% bootstrap support, and Flavobacterium into nine (A-I). Phylogenetic clades showed distinct patterns in antimicrobial susceptibility. Two Chryseobacterium clades (F & G), and four Flavobacterium clades (B, G-I) had comparably high minimal inhibitory concentrations (MICs) for 11/18 antimicrobials tested. Multiple clades in both genera exhibited MICs surpassing the established F. psychrophilum breakpoints for oxytetracycline and florfenicol, indicating potential resistance to two of the three antimicrobials approved for use in finfish aquaculture. Further work to investigate the virulence and antigenic diversity of these genetic groups will improve our understanding of flavobacterial disease, with applications for treatment and vaccination strategies.

Genomic insight into Chryseobacterium turcicum sp. nov. and Chryseobacterium muglaense sp. nov. isolated from farmed rainbow trout in Turkey

Four strains, designated as C-2, C-17^T, C-39^T and Ch-15, were isolated from farmed rainbow trout samples showing clinical signs during an investigation for a fish-health screening study. The pairwise 16S rRNA gene sequence analysis showed that strain C-17^T shared the highest identity level of 98.1 % with the type strain of Chryseobacterium piscium LMG 23089^T while strains C-2, C-39^T and Ch-15 were closely related to Chryseobacterium balustinum DSM 16775^T with an identity level of 99.3 %. A polyphasic approach involving phenotypic, chemotaxonomic and genome-based analyses was employed to determine the taxonomic provenance of the strains. The overall genome relatedness indices including dDDH and ANI analyses confirmed that strains C-2, C-17^T, C-39^T and Ch-15 formed two novel species within the genus Chryseobacterium. Chemotaxonomic analyses showed that strains C-17^T and C-39^T have typical characteristics of the genus Chryseobacterium by having phosphatidylethanolamine in their polar lipid profile, MK-6 as only isoprenoid quinone and the presence of iso-C_15:0 as major fatty acid. The genome size and G + C content of the strains ranged between 4.4 and 5.0 Mb and 33.5 - 33.6 %, respectively. Comprehensive genome analyses revealed that the strains have antimicrobial resistance genes, prophages and horizontally acquired genes in addition to secondary metabolite-coding gene clusters. In conclusion, based on the polyphasic analyses conducted on the present study, strains C-17^T and C-39^T are representatives of two novel species within the genus Chryseobacterium, for which the names Chryseobacterium turcicum sp. nov. and Chryseobacterium muglaense sp. nov. with the type strains C-17^T (=JCM 34190^T = KCTC 82250^T) and C-39^T (=JCM 34191^T = KCTC 822251^T), respectively, are proposed.

Assessment of Bacterial Diversity of Industrial Poultry Wastewater by Denaturing Gradient Gel Electrophoresis (DGGE) and the Cultivation Method in Order to Inform Its Reuse in Agriculture

Effluents discharged by poultry meat industries are heavily polluted with raw materials, such as fat, blood residues, and proteins. Thus, untreated effluents directly discharged into the environment may constitute a public health threat. This study aims to evaluate the bacterial diversity of three water qualities: industrial poultry wastewater (PWW), tap water (TW), and PWW diluted with TW (50 : 50) (V/V) (TWPWW) by the combination of culture-independent and culture-dependent approaches. The total bacterial DNA was extracted using phenol/chloroform method. The hypervariable 16S rRNA region V3-V5 was amplified by PCR using universal primers. The amplicons were separated by vertical electrophoresis on a polyacrylamide gel of increasing denaturing gradient according to their richness in GC bases. Selected bands were reamplified and sequenced. Pure isolated bacteria from nutrient agar medium were characterized according to their morphological and biochemical characteristics. Genomic DNA from pure strains was extracted by boiling method, and a molecular amplification of the 16S–23S ITS region of the 16S rRNA gene was performed using the universal primers. Selected isolates were identified by sequencing. Results showed a high bacterial load and diversity in PWW in comparison with TW and TWPWW. A collection of 44 strains was obtained, and 25 of them were identified by sequencing. Proteobacteria represented 76% of isolated bacteria Gamma-Proteobacteria was the predominate isolate (68%). Other isolates were Firmicutes (8%), Bacteroidetes (12%), and Actinobacteria (8%). These isolates belong to different genera, namely, Pseudomonas, Acinetobacter, Proteus, Empedobacter, Corynebacterium, Enterobacter, Comamonas, Frondibacter, Leclercia, Staphylococcus, Atlantibacter, Klebsiella, and Microbacterium.

Characterization of Bacterial Communities from the Surface and Adjacent Bottom Layers of Water in the Billings Reservoir

Here, we describe the bacterial diversity and physicochemical properties in freshwater samples from the surface and bottom layers of the Billings Reservoir, the largest open-air storage ecosystem in the São Paulo (Brazil) metropolitan area. Forty-four samples (22 from the surface and 22 from the bottom layers) were characterized based on 16S rRNA gene analysis using Illumina MiSeq. Taxonomical composition revealed an abundance of the Cyanobacteria phylum, followed by Proteobacteria, which were grouped into 1903 and 2689 different genera in the surface and the deep-water layers, respectively. Chroobacteria, Actinobacteria, Betaproteobacteria, and Alphaproteobacteria were the most dominant classes. The Shannon diversity index was in the range of 2.3–5.39 and 4.04–6.86 in the surface and bottom layers, respectively. Flavobacterium was the most predominant pathogenic genus. Temperature and phosphorus concentrations were among the most influential factors in shaping the microbial communities of both layers. Predictive functional analysis suggests that the reservoir is enriched in motility genes involved in flagellar assembly. The overall results provide new information on the diversity composition, ecological function, and health risks of the bacterial community detected in the Billings freshwater reservoir. The broad bacterial diversity indicates that the bacterioplankton communities in the reservoir were involved in multiple essential environmental processes.

PCR Analysis for Genetic Distances of Two Charybdis Crab Populations

Genomic DNA (gDNA) set apart from two populations of Korean Charybdis crab (Charybdis japonica) was augmented by PCR experiments. The five oligonucleotides primers (ONT-primers) were spent to yield the number of unique loci shared to each crab population (ULSECP) and number of loci shared by the two crab populations (LSTCP). 305 fragments (FRAGs) were identified in the Charybdis crab population A (CCPA), and 344 in the Charybdis crab population B (CCPB): 44 number of ULSECP (14.43%) in the CCPA and 110 (31.98%) in the CCPB. 44 number of LSTCP, with an average of 8.8 per primer, were detected in the two crab populations. The bandsharing (BS) value between entity’s no. 01 and no. 10 was the lowest (0.371) between the two CCPs. The average bandsharing (ABS) values of individuals in the CCPA (0.575±0.014) were lesser than in those originated from the CCPB (0.705±0.011) (p < 0.05). The polar hierarchical dendrogram (PHD) achieved by the five ONT-primers denotes three genetic clusters (GCs): cluster I (CHARYBCRAB 01, 04, 05, 06, and 08), cluster II (CHARYBCRAB 02, 03, 07, 09, 10, and 11) and cluster III (CHARYBCRAB 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, and 22). The shortest genetic distance (GD) displaying significant molecular difference (MD) was between individuals CHARYBCRAB no. 18 and CHARYBCRAB no. 17 (0.055).

The Bacteroidetes Aequorivita sp. and Kaistella jeonii Produce Promiscuous Esterases With PET-Hydrolyzing Activity

Certain members of the Actinobacteria and Proteobacteria are known to degrade polyethylene terephthalate (PET). Here, we describe the first functional PET-active enzymes from the Bacteroidetes phylum. Using a PETase-specific Hidden-Markov-Model- (HMM-) based search algorithm, we identified several PETase candidates from Flavobacteriaceae and Porphyromonadaceae. Among them, two promiscuous and cold-active esterases derived from Aequorivita sp. (PET27) and Kaistella jeonii (PET30) showed depolymerizing activity on polycaprolactone (PCL), amorphous PET foil and on the polyester polyurethane Impranil® DLN. PET27 is a 37.8 kDa enzyme that released an average of 174.4 nmol terephthalic acid (TPA) after 120 h at 30°C from a 7 mg PET foil platelet in a 200 μl reaction volume, 38-times more than PET30 (37.4 kDa) released under the same conditions. The crystal structure of PET30 without its C-terminal Por-domain (PET30ΔPorC) was solved at 2.1 Å and displays high structural similarity to the IsPETase. PET30 shows a Phe-Met-Tyr substrate binding motif, which seems to be a unique feature, as IsPETase, LCC and PET2 all contain Tyr-Met-Trp binding residues, while PET27 possesses a Phe-Met-Trp motif that is identical to Cut190. Microscopic analyses showed that K. jeonii cells are indeed able to bind on and colonize PET surfaces after a few days of incubation. Homologs of PET27 and PET30 were detected in metagenomes, predominantly aquatic habitats, encompassing a wide range of different global climate zones and suggesting a hitherto unknown influence of this bacterial phylum on man-made polymer degradation.

The Integrative and Conjugative Element ICECspPOL2 Contributes to the Outbreak of Multi-Antibiotic-Resistant Bacteria for Chryseobacterium Spp. and Elizabethkingia Spp

Antibiotic resistance genes (ARGs) and horizontal transfer of ARGs among bacterial species in the environment can have serious clinical implications as such transfers can lead to disease outbreaks from multidrug-resistant (MDR) bacteria. Infections due to antibiotic-resistant Chryseobacterium and Elizabethkingia in intensive care units have been increasing in recent years. In this study, the multi-antibiotic-resistant strain Chryseobacterium sp. POL2 was isolated from the wastewater of a livestock farm. Whole-genome sequencing and annotation revealed that the POL2 genome encodes dozens of ARGs. The integrative and conjugative element (ICE) ICECspPOL2, which encodes ARGs associated with four types of antibiotics, including carbapenem, was identified in the POL2 genome, and phylogenetic affiliation analysis suggested that ICECspPOL2 evolved from related ICEEas of Elizabethkingia spp. Conjugation assays verified that ICECspPOL2 can horizontally transfer to Elizabethkingia species, suggesting that ICECspPOL2 contributes to the dissemination of multiple ARGs among Chryseobacterium spp. and Elizabethkingia spp. Because Elizabethkingia spp. is associated with clinically significant infections and high mortality, there would be challenges to clinical treatment if these bacteria acquire ICECspPOL2 with its multiple ARGs, especially the carbapenem resistance gene. Therefore, the results of this study support the need for monitoring the dissemination of this type of ICE in Chryseobacterium and Elizabethkingia strains to prevent further outbreaks of MDR bacteria. IMPORTANCE Infections with multiple antibiotic-resistant Chryseobacterium and Elizabethkingia in intensive care units have been increasing in recent years. In this study, the mobile integrative and conjugative element ICECspPOL2, which was associated with the transmission of a carbapenem resistance gene, was identified in the genome of the multi-antibiotic-resistant strain Chryseobacterium sp. POL2. ICECspPOL2 is closely related to the ICEEas from Elizabethkingia species, and ICECspPOL2 can horizontally transfer to Elizabethkingia species with the tRNA-Glu-TTC gene as the insertion site. Because Elizabethkingia species are associated with clinically significant infections and high mortality, the ability of ICECspPOL2 to transfer carbapenem resistance from environmental strains of Chryseobacterium to Elizabethkingia is of clinical concern.

Diet diversity and environment determine the intestinal microbiome and bacterial pathogen load of fire salamanders

Diverse communities of symbiotic microbes inhabit the digestive systems of vertebrates and play a crucial role in animal health, and host diet plays a major role in shaping the composition and diversity of these communities. Here, we characterized diet and gut microbiome of fire salamander populations from three Belgian forests. We carried out DNA metabarcoding on fecal samples, targeting eukaryotic 18S rRNA of potential dietary prey items, and bacterial 16S rRNA of the concomitant gut microbiome. Our results demonstrated an abundance of soft-bodied prey in the diet of fire salamanders, and a significant difference in the diet composition between males and females. This sex-dependent effect on diet was also reflected in the gut microbiome diversity, which is higher in males than female animals. Proximity to human activities was associated with increased intestinal pathogen loads. Collectively, the data supports a relationship between diet, environment and intestinal microbiome in fire salamanders, with potential health implications.

Genetic Variations within and between Blue Crab (Portunus trituberculatus) Groups

The five oligonucleotide primers (oligo-primers) turned out a total of 335 fragments (FMs) (52.9%) in the blue crab (Portunus trituberculatus) group alpha and 298 FMs (47.1%) in the crab group beta, with the FM scales range varying from 100 bp to 2,000 bp. The highest band-sharing (BS) value (0.907) was found between individual's no. 19 and no. 20 within the blue crab group beta. Parties in the blue crab group beta (0.601±0.017) had higher BS rates than did parties from the crab group alpha (0.563±0.017) (p<0.05). The polar dendrogram got by the five oligo-primers points out two genetic extents: bundle I (BLUECRAB 01, 03, 04, 05, 06, 08, and 10) and bundle II (BLUECRAB 02, 07, 09. 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, and 22). The OPD-01 primer revealed 22 loci shared by all the examples of the as FMs of 1,000 bp. The oligo-primer OPA-05 made unique loci shared to each group (ULSEG), almost 400 bp and 500 bp, individually, in blue crab group beta. The remaining oligo-primers did not reveal any loci shared by the two crab groups (LSTG). The average number of ULSEG was diverse and 1.6-fold higher in the crab group beta than in the crab group alpha.

Oral Abscess Caused by Chryseobacterium indologenes in Ball Python (Python regius); A Case Report

Chryseobacterium indologenes is an opportunistic pathogen isolated from human infections and, rarely, from some aquatic animals. A 3-year-old male ball python (Python regius) was admitted to the veterinary clinic by a pet owner because of acute respiratory and swallowing failure. During physical examinations, oral secretions and abscesses were observed in the mouth cavity and throat of the animal. After microbiological analysis including isolation, identification, and 16s rRNA sequencing, C. indologenes was detected as the main cause of the oral abscess in this case. Phylogenetic relatedness analysis showed a close relationship between this isolate and other strains isolated from human infections. Antimicrobial susceptibility testing revealed that the isolate was multi-drug resistant. However, it was very sensitive to minocycline, ceftazidime, and tetracycline. The patient was treated by antibiotic therapy and completely recovered after two weeks. To the best of our knowledge, this is the first incidence of C. indologenes in an oral abscess in a ball python. As a result we would consider this organism as an opportunistic animal pathogen with zoonotic potentiality.

Heterologous expression and characterisation of a keratinase produced by Chryseobacterium carnipullorum

Chryseobacterium carnipullorum 9_R23581^T, isolated from raw chicken meat, was evaluated for its potential to degrade keratin found in feathers. The focus of this study was to heterologously express and characterise a keratinolytic enzyme produced by C. carnipullorum. Chryseobacterium carnipullorum secretes proteolytic enzymes that have feather degrading capabilities during its exponential growth phase. This study concluded that the most likely main component of the keratinolytic enzymes of C. carnipullorum was peptidase M64, a serine-endopeptidase with a molecular weight in crude form of 49.46 kDa. Primers were designed on the selected gene of interest, which was amplified from the genome of C. carnipullorum (accession number NZ-FRCD01000002.1). The gene coding for peptidase M64 was further cloned, propagated and expressed in E. coli BL21 [DE3] cells. Purification was by Immobilised Metal Affinity Chromatography (IMAC). The molecular weight of the keratinase was about 50 kDa after purification while its optimum temperature and pH were 50 °C and 8.5, respectively. The activity of this keratinase was inhibited by phenylmethylsulfonyl fluoride (PMSF) and it was enhanced by the presence of divalent metal ions such as Mg²⁺ and Ca²⁺. Enzyme activity was further assayed by application to chicken feathers and observed degradation was an indication of keratinolytic potential.

Salegentibacter maritimus sp. nov., isolated from marine coastal sediment

Two bacterial strains were isolated from a marine sediment sample taken from Jingzi Wharf, Weihai, China. These two strains were characterized at the phenotypic, chemotaxonomic, and genomic level. The two strains possessed almost identical 16S rRNA gene sequences (99.9 %). However, RAPD-PCR fingerprint patterns discriminated that they were not from one clonal origin. The average nucleotide identity (ANI) value and the digital DNA-DNA hybridization (dDDH) value between the two strains were 98.3 % and 85.4 %, respectively, suggestingthat they belonged to the same species. On the basis of the result of phylogenetic analysis of the 16S rRNA gene sequences, the two strains belonged to the genus Salegentibacter and were closely related to S. holothuriorum KCTC 12371^T (98.6 %) and S. salegens DSM 5424^T (98.2-98.3 %). The ANI and dDDH clearly separated strains F63223^T and F60176 from the the most related type strains with values below the thresholds for species. The genome sizes of strains F63223^T and F60176 were approximate 3.89 and 3.59 Mbp, respectively. The strain F63223^T had 3,335 predicted genes with DNA G + C content of 35.6 %. The major respiratory quinone was MK-6 and the major polar lipids were phosphatidylethanolamine and one unidentified lipid. According to the results of the phenotypic, chemotaxonomic characterization, phylogenetic classification and genome analysis, the two isolates could be considered to represent a novel species of the genus Salegentibacter, for which the name Salegentibacter maritimus sp. nov., is proposed, with F63223^T (=MCCC 1H00433^T = KCTC 82417^T) as the type strain.

Kaistella gelatinilytica sp. nov., a flavobacterium isolated from Antarctic soil

A Gram-stain-negative, aerobic, non-spore-forming, rod-shaped, non-motile, yellow-pigmented bacteria, designated strain G5-32^T, belonging to the genus Kaistella was isolated from soil collected in the Antarctic. The strain was identified using a polyphasic taxonomic approach. The strain grew in the presence of 0-5% (w/v) NaCl (optimum, 1%), at pH 6.0-9.0 (optimum, pH 8.0) and at 4-28 °C (optimum, 20 °C). The predominant menaquinone was MK-6 (99.4%). The major fatty acids were anteiso-C_15:0 (28.2%), iso-C_15:0 (16.4%), summed feature 9 (comprising iso-C_17:1 ω9c and/or 10-methyl C_16:0; 10.6%) and iso-C_16:0 (5.9%). A phylogenetic tree based on 16S rRNA gene sequences showed that strain G5-32^T formed a lineage within the genus Kaistella with the closest phylogenetic neighbours Kaistella yonginensis HMD1043^T, Kaistella chaponensis DSM 23145^T, Kaistella jeonii DSM 17048^T and Kaistella carnis NCTC 13525^T (97.9, 97.8, 97.8 and 98.0 % 16S rRNA gene sequence similarity, respectively). The ANI values between strain G5-32^T and K. jeonii DSM 17048^T, K. chaponensis DSM 23145^T, K. carnis NCTC 13525^T and K. yonginensis HMD1043^T were 90.9, 82.6, 77.1 and 76.3%. Concurrently, digital DNA-DNA hybridization values of strain G5-32^T assessed against K. jeonii DSM 17048^T, K. chaponensis DSM 23145^T, K. carnis NCTC 13525^T and K. yonginensis HMD1043^T were 42.3, 25.9, 21.7 and 21.3%, respectively. Based on phenotypic, phylogenetic and genotypic data, a novel species, Kaistella gelatinilytica sp. nov., is proposed. The type strain is G5-32^T (=CCTCC AA 2019083^T=KCTC 72766^T).

Elizabethkingia miricola infection in multiple anuran species

This report describes an outbreak of Elizabethkingia miricola in northern leopard frogs (Lithobates pipiens) and three other species of frogs and toads held in captivity in Germany. The authors examine several treatment options and underline the difficulties in treating larger numbers of individuals with antimicrobials applied through bathing. Whole genome sequencing of three bacterial isolates emphasizes their relatedness to other frog isolates and leads us to conclude that E. miricola is an emerging and difficult to treat pathogen with a broad host range across anuran species. Moreover, ambiguities in identification of flavobacteria associated with disease in frogs reported in the literature make it seem possible that E. miricola has been overlooked as an anuran pathogen in the past.

First Isolation and Characterization of Chryseobacterium cucumeris SKNUCL01, Isolated from Diseased Pond loach (Misgurnus anguillicaudatus) in Korea

Loaches are widely distributed throughout the natural environment and are consumed for medicinal purposes in East Asia. Usually, loaches are cultured in ponds where the water conditions can easily cause bacterial infections. Infections due to bacterial pathogens such as Aeromonas have been well described in cultured loaches; however, there is no report regarding Chryseobacterium infection. This study focused on the elucidation of the pathogenic and antibiotic resistance characteristics of C. cucumeris, SKNUCL01, isolated from diseased loaches (Misgurnus anguillicaudatus). SKNUCL01 forms a biofilm, which is associated with its virulence. Koch’s postulates were satisfied with a lethal dose 50 (LD₅₀) of 8.52 × 10⁷ colony-forming units (CFU)/ml. Abrasion facilitates the mortality of the fish, which makes it a possible infection route for C. cucumeris. The strain showed resistance to nearly all tested antibiotics, such as trimethoprim/sulfamethoxazole, levofloxacin, and ciprofloxacin, formerly considered effective treatments. Phenotypic analyses for antibiotic resistance—the combined disk test, double-disk synergy test, modified Hodge test, and efflux pump inhibition test—revealed that the resistance of SKNUCL01 originated from metallo-beta lactamases (MBLs) and efflux pumps. Our findings provide evidence that could result in a breakthrough against multidrug-resistant Chryseobacterium infection in the aquaculture industry; the antibiotic resistance-related genes can be elucidated through future study.

Risk Factors for Mortality in Patients with Elizabethkingia Infection and the Clinical Impact of the Antimicrobial Susceptibility Patterns of Elizabethkingia Species

Elizabethkingia species (spp.), which can colonize hospital environments, are emerging nosocomial pathogens presenting high mortality. Due to their intrinsic resistance to a broad range of antibiotics, optimal antibiotic dosage has yet to be determined against infections caused by Elizabethkingia spp. This study aimed to investigate the risk factors for the mortality of infections caused by Elizabethkingia spp. and assess the clinical implications of their antimicrobial susceptibility patterns. Data from 210 patients affected by Elizabethkingia-induced pneumonia and bacteremia between 1 November 2005 and 31 May 2016, were analyzed. Further antimicrobial susceptibility tests for moxifloxacin, rifampin, and vancomycin using Elizabethkingia isolates were performed to compensate for the Elizabethkingia spp. susceptibility panel in patients affected after 2013. The mean age of the patients was 66.5 ± 18 years and the 28-day mortality rate was 25.2% (53/210). In the univariate analysis, history of prior stay in an intensive care unit, central venous catheter use, presented thrombocytopenia, immunocompetent status, a high simplified acute physiology score II (SAPS II score), a high C-reactive protein (CRP)/albumin ratio on the day of isolation and seven days later, and a high minimum inhibitory concentration (MIC) value of rifampin were significantly associated with a higher mortality rate. In the multivariate logistic regression analysis, the MIC values of rifampin (odds ratio (OR): 1.045; 95% confidence interval (CI): 1.006–1.085; p = 0.023), SAPS II score (OR: 1.053; 95% CI: 1.022–1.084; p = 0.001), and initial CRP/albumin ratio (OR: 1.030; 95% CI: 1.009–1.051; p = 0.004) were significantly associated with 28-day mortality. To reduce the mortality associated with Elizabethkingia infections, prediction of the clinical course using initial CRP/albumin ratio and SAPS II and early intervention are essential. Rifampin is a promising candidate as the drug of choice in treating Elizabethkingia infections.

A real-time PCR assay for detection of emerging infectious Elizabethkingia miricola

Elizabethkingia miricola, a Gram-negative bacillus, is emerging as a life-threatening pathogen in both humans and animals. However, no specific and rapid diagnostic method exists to detect E. miricola. Here, we established a real-time PCR assay for the rapid, sensitive, and specific detection of E. miricola with a wide dynamic range of 10⁸ copies/μL to 10² copies/μL. The detection limit of the real-time assay was 145 copies/μL, which was 100 times more sensitive than conventional PCR. All clinical isolates E. miricola from different host species yield very close Tm (80.25 ± 0.25 °C). Additionally, no cross-reaction or false positives were observed in the assay for non-target bacterial species. The performance of this assay was primarily assessed by testing frog tissue samples. Overall, our study provided a real-time PCR assay, which is a rapid, sensitive, and specific diagnostic method that could be used for early diagnosis and epidemiological investigation of E. miricola.

Chryseobacterium lacus sp. nov. Isolated From the Surface Water of Two Lakes With Light-Induced Carotenoid Production

Two Gram-stain-negative, rod-shaped, gliding, catalase-positive, and facultative anaerobic strains, YLOS41^T and XH07, were isolated from surface water of Yilong Lake and West Lake of Dali in Yunnan Province, respectively. Both strains were yellow-colored under light conditions and white-colored under dark conditions. The results of physiological and chemotaxonomic characterization, sequencing and phylogenetic analysis, and draft genome sequence comparison demonstrated that the two strains represented a single novel species within the genus Chryseobacterium, for which the name Chryseobacterium lacus sp. nov. is proposed. The type strain is YLOS41^T (= KCTC 62352^T = MCCC 1H00300^T), and the second strain is XH07 (= KCTC 62993). During the cultivation process, we found that the colony color of the two strains changed from white to yellow with illumination. The study investigated the effects of light irradiation on the strain YLOS41^T. Results showed that light irradiation did not affect the growth of cells but significantly increased carotenoid synthesis, which caused the change of colony color. In-depth metabolic analysis was conducted by transcriptome. The predominant changes were found for genes involved in carotenoid synthesis as protection from light damage. Based on the genome and transcriptome, we proved that strain YLOS41^T possessed a complete synthetic pathway of carotenoid and speculated that the production was zeaxanthin. This was the first report of Chryseobacterium species with light-induced carotenoid synthesis. This study enhances our present knowledge on how Chryseobacterium species isolated from surface water responds to light damage.

A Real-Time Multiplex PCR Assay for Detection of Elizabethkingia Species and Differentiation between Elizabethkingia anophelis and E. meningoseptica

Nosocomial infections of Elizabethkingia species can have fatal outcomes if not identified and treated properly. The current diagnostic tools available require culture and isolation, which can extend the reporting time and delay treatment. Using comparative genomics, we developed an efficient multiplex real-time PCR for the simultaneous detection of all known species of Elizabethkingia, as well as differentiating the two most commonly reported species, Elizabethkingia anophelis and Elizabethkingia meningoseptica.

Isolation and Characterization of Flavobacteriaceae from Farmed and Wild Nile Tilapia in Tanzania

The present study was conducted to explore the occurrence of Flavobacteriaceae in wild Nile Tilapia Oreochromis niloticus (n = 108) collected from Lake Victoria and farmed Nile Tilapia (n = 187) collected from 12 ponds in the Morogoro region of Tanzania. The size of the ponds surveyed ranged from 130 to 150 m² . Pond parameters and fish morphometric data were recorded during sampling. In total, 67 Flavobacterium-like isolates (n = 44 from farmed fish; n = 23 from wild fish) were identified on the basis of colony morphology and biochemical tests. Sequences from the 16S ribosomal RNA (rRNA) gene revealed that all 67 isolates belonged to the genera Flavobacterium and Chryseobacterium. Based on 16S rRNA nucleotide identity, 26 isolates showed high similarity with C. indologenes (99-100% identity), 16 showed similarity to C. joostei (98-99.9%), and 17 were similar to diverse species of Chryseobacterium (97-99%). Three isolates were similar to F. aquatile and three were similar to F. indicum, with 99-100% nucleotide identity in both cases, and two isolates were similar to F. oryzae (99-100% identity). The findings obtained in this study provide a baseline for future studies and contribute to an understanding of the threats presented by the aquatic Flavobacteriaceae reservoir toward the development of healthy fish farming in Tanzania. Such knowledge is vital for the development of a sustainable aquaculture industry in Tanzania that will contribute to increased food security.

Maribacter litoralis sp. nov. a marine bacterium isolated from seashore

A novel Gram-stain-negative, moderately halophilic and aerobic bacterium, designated strain SDRB-Phe2^T, was isolated from coastal sediment of the yellow sea in Sindu-ri, Republic of Korea. Cells were oxidase-positive, catalase-positive, rod-shaped and surrounded by a capsule with gliding motility. Colonies were yellow-coloured, circular, pulvinate with entire margins. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain SDRB-Phe2^T formed a distinct lineage within the genus Maribacter of the family Flavobacteriaceae. Stain SDRB-Phe2^T exhibited 16S rRNA gene sequence similarity values of 97.1-98.9 % to the type strains of Maribacterstanieri, Maribacterspongiicola, Maribacter forsetii, Maribacter dokdonensis, Maribacter aquivivus, Maribactercaenipelagi, Maribacterlitorisediminis, Maribactersedimenticola, Maribacterulvicola, Maribacter confluentis and Maribacter orientalis, and of 94.8-96.7 % to the type strains of the other species of the genus Maribacter. Strain SDRB-Phe2^T contained MK-6 as the predominant respiratory quinone and iso-C15 : 1 G, iso-C15 : 0 and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) as the major fatty acids. The polar lipids of strain SDRB-Phe2^T were phosphatidylethanolamine, one unidentified amino lipid and two unidentified lipids. The DNA G+C content was 36.2 mol%. DNA-DNA relatedness values of strain SDRB-Phe2^T to the type strains of the 11 phylogenetically related species of the genus Maribacter were 21.9-38.6 %. On the basis of the phenotypic features, phylogenetic and DNA-DNA hybridization analyses presented here, strain SDRB-Phe2^T (=JCM 32373^T=KCTC 62273^T=DSM 106042^T) represents a novel species of the genus Maribacter, for which the name Maribacterlitoralis sp. nov. is proposed.

First isolation and identification of Aeromonas veronii and Chryseobacterium joostei from reared sturgeons in Fars province, Iran

The purpose of the present study was to isolate and identify the pathogenic agents in Acipenser stellatus (Pallas, 1771) and Huso huso, (Linnaeus, 1758) reared in the south of Fars province, Iran which have shown infectious disease signs. Samples from spleen and kidney of 32 fishes showing septicemia symptoms such as decreasing of appetite, unbalanced swimming, expanded wounds, and petechia on the body surfaces, pectoral fins rot, visceral hemorrhage, bleeding on the spleen, and heart ascites were collected. Then samples were cultured on brain heart infusion agar growth media, stain and biological and biochemical tests on purified bacteria were performed. On the other hand, 16S rDNA region of the isolated organism was amplified using PCR. The amplified gene fragment was sequenced and evolutionary history was inferred by phylogenetic tree construction using neighbor-joining method. Results indicated that two bacterial species including Chryseobacteriumjoostei which isolated from the kidney of stellate sturgeon (43.00%), and Aeromonasveronii which isolated from the spleen of both sturgeon species (75.00% and 31.00% from beluga and stellate sturgeon, respectively), were recognized. Phylogenetic tree analysis showed that Fars isolated organisms including A. veronii and C. joostei had highest similarity with A. veronii bv veronii and C. joostei isolated from France, respectively.

Soortia roseihalophila gen. nov., sp. nov., a new taxon in the order Balneolales isolated from a travertine spring, and description of Soortiaceae fam. nov

A novel Gram-stain-negative, slightly halophilic, motile, curved rod with a horseshoe shape, designated strain Bsw-2bT, was isolated from Badab-Soort travertine spring in Iran. Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain Bsw-2bT belongs to the order Balneolales, showing 84.6 % sequence similarity to Gracilimonastropica DSM 19535T and 84.4 % and 83.9 % sequence similarity to Gracilimonas rosea CL-KR2T and Balneola vulgaris DSM 17893T, respectively. In addition, phenotypic and physiological features could clearly differentiate strain Bsw-2bT from species of the most closely related genera, Gracilimonas, Balneola, Aliifodinibius and Fodinibius. The strain was able to grow with 1-3 % (w/v) (optimum at 2 %) NaCl, at temperatures of 28-34 °C (optimum at 30 °C) and between pH 6.0 and 8.0 (optimum at pH 7.0). The major cellular fatty acids of strain Bsw-2bT were iso-C15 : 0, iso-C13 : 0 and iso-C14 : 0. The polar lipid profile of strain Bsw-2bT was composed predominantly of phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, an unknown glycolipid and four unknown phospholipids. The DNA G+C content was 40.5 mol%. Based on the evidence from the polyphasic study, strain Bsw-2bT represents a novel species in a novel genus within a new family, for which the name Soortia roseihalophila gen. nov., sp. nov. is proposed, within the new family Soortiaceae fam. nov. The type strain is strain Bsw-2bT (=IBRC-M 10915T=LMG 28547T).

Gut microbiota isolated from the European pond turtle (Emys orbicularis) and its antimicrobial resistance

The aim of the study was to isolate cultivable gut microbiota from European pond turtles kept at the Lithuanian Zoo and to determine antimicrobial resistance of the isolates. The study subjects included 8 elderly turtles living at the Lithuanian Zoo for about 50 years as well as their offspring – 24 young individuals (1-2 years old) that were hatched at the same zoo. Animals were not exposed by treatment with antimicrobials during the last 3 years.

Gut samples were taken from the cloaca and inoculated onto universal media. Isolates then were identified using sequence analysis of 16S rRNA.

The antimicrobial susceptibility testing was performed using the agar diffusion method according to Kirby-Bauer. Clinical breakpoints according to CLSI whenever possible, were used for interpretation of susceptibility. Bacterial isolates resistant to at least three antimicrobials of different classes were treated as multi-resistant.

Fifty-two bacterial isolates were obtained and identified from turtle gut samples. The most prevalent genera includedAeromonas, ChryseobacteriumandCitrobacter.Fifty percent of the isolates obtained from elderly turtles (CI 95% – 19.01-80.99) and 54.8% (CI 95% – 39.75-69.85) of the isolates from young animals were identified as multi-resistant. The most common resistance rates of the isolates from both groups of the turtles were observed toward ampicillin (86.6%), ciprofloxacin (61.5%) and gentamicin (40.4%). The lowest number of resistant isolates were detected toward combination of sulfamethoxazole-trimethoprim (26.9%). The study revealed that European pond turtles kept in captivity are carriers of multi-resistant bacteria however, further studies need to be performed to investigate whether the resistant microorganisms are natural microbiota for this species or they were acquired in the zoo.

New host record of five Flavobacterium species associated with tropical fresh water farmed fishes from North India

Yellow pigmented, filamentous, Gram-negative bacteria belonging to genus Flavobacterium are commonly associated with infections in stressed fish. In this study, inter-species diversity of Flavobacterium was studied in apparently healthy freshwater farmed fishes. For this, ninety one yellow pigmented bacteria were isolated from skin and gill samples (n = 38) of three farmed fish species i.e. Labeo rohita, Catla catla and Cyprinus carpio. Among them, only twelve bacterial isolates (13.18%) were identified as Flavobacterium spp. on the basis of morphological, biochemical tests, partial 16S rDNA gene sequencing and phylogenetic analysis. On the basis of 16S rDNA gene sequencing, all the 12 isolates were 97.6-100% similar to six different formally described species of genus Flavobacterium. The 16S rDNA based phylogenetic analysis grouped these strains into six different clades. Of the 12 isolates, six strains (Fl9S1-6) grouped with F. suncheonense, two strains (Fl6I2, Fl6I3) with F. indicum and the rest four strains (Fl1A1, Fl2G1, Fl3H1 and Fl10T1) clustered with F. aquaticum, F. granuli, F. hercynium and F. terrae, respectively. None of these species except, F. hercynium were previously reported from fish. All the isolated Flavobacterium species possessed the ability of adhesion and biofilm formation to colonize the external surface of healthy fish. The present study is the first record of tropical freshwater farmed fishes as hosts to five environmentally associated species of the Flavobacterium.

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.

Chryseobacterium frigidum sp. nov., isolated from high-Arctic tundra soil, and emended descriptions of Chryseobacterium bernardetii and Chryseobacterium taklimakanense

A yellow, Gram-reaction-negative, non-motile, aerobic bacterium, designated D07^T, was isolated from a tundra soil near Ny-Ålesund, Svalbard archipelago, Norway (78° N). Growth occurred at 4-37 °C (optimum 28-30 °C) and at pH 6.0-9.0 (optimum pH 7.0-8.0). The strain produced flexirubin-type pigments. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain D07^T belonged to the genus Chryseobacterium in the family Flavobacteriaceae. The 16S rRNA gene sequence of this strain showed 93.83 and 93.31 % sequence similarity, respectively, to those of Chryseobacterium contaminans C26^T and Chryseobacterium taklimakanense X-65^T. Strain D07^T contained anteiso-C_15 : 0 (25.91 %), iso-C_15 : 0 (16.05 %), iso-C_16 : 0 3-OH (9.64 %), iso-C_16 : 0 (9.42 %) and iso-C_14 : 0 (7.36 %) as the predominant cellular fatty acids, MK-6 as the major respiratory quinone and phosphatidylethanolamine, five unknown aminolipids and three unknown lipids as the main polar lipids. The DNA G+C content was 49.3 mol%. On the basis of phenotypic, chemotaxonomic and phylogenetic data, strain D07^T is considered to represent a novel species of the genus Chryseobacterium, for which the name Chryseobacterium frigidum sp. nov. is proposed. The type strain is D07^T ( = CCTCC AB 2011160^T = KCTC 42897^T). Emended descriptions of Chryseobacterium bernardetii and Chryseobacterium taklimakanense are also provided.

Polyphasic characterization reveals the presence of novel fish-associated Chryseobacterium spp. in the Great Lakes of North America

Recent reports suggest an emergence of novel Chryseobacterium spp. associated with aquaculture-reared fish worldwide. Herein, we report on multiple Chryseobacterium spp. infecting Great Lakes fishes that are highly similar to previously detected isolates from Europe, Africa, and Asia but have never before been reported in North America. Polyphasic characterization, which included extensive physiological, morphological, and biochemical analyses, fatty acid profiling, and phylogenetic analyses based upon partial 16S rRNA gene sequences, highlighted the diversity of Great Lakes' fish-associated chryseobacteria and also suggested that at least 2 taxa represent potentially novel Chryseobacterium spp. Screening for the ability of representative chryseobacteria to elicit lesions in experimentally challenged fish showed that they induced varying degrees of pathology, some of which were severe and resulted in host death. Median lethal dose (LD50) experiments for the isolate that elicited the most extensive pathology (Chryseobacterium sp. T28) demonstrated that the LD50 exceeded 4.5 × 108 cfu, thereby suggesting its role as a facultative fish-pathogenic bacterium. Histopathological changes in T28-infected fish included epithelial hyperplasia of the secondary lamellae and interlamellar space that resulted in secondary lamellar fusion, monocytic infiltrate, and mucus cell hyperplasia, all of which are consistent with branchitis, along with monocytic myositis, hemorrhage within the muscle, liver, adipose tissue, and ovaries, spongiosis of white matter of the brain, multifocal edema within the granular cell layer of the cerebellar cortex, and renal tubular degeneration and necrosis. The findings of this study underscore the widespread presence of chryseobacteria infecting Great Lakes fish.

Bacterial diversity associated with wild caught Anopheles mosquitoes from Dak Nong Province, Vietnam using culture and DNA fingerprint

Background

Microbiota of Anopheles midgut can modulate vector immunity and block Plasmodium development. Investigation on the bacterial biodiversity in Anopheles, and specifically on the identification of bacteria that might be used in malaria transmission blocking approaches, has been mainly conducted on malaria vectors of Africa. Vietnam is an endemic country for both malaria and Bancroftian filariasis whose parasitic agents can be transmitted by the same Anopheles species. No information on the microbiota of Anopheles mosquitoes in Vietnam was available previous to this study.

Method

The culture dependent approach, using different mediums, and culture independent (16S rRNA PCR – TTGE) method were used to investigate the bacterial biodiversity in the abdomen of 5 Anopheles species collected from Dak Nong Province, central-south Vietnam. Molecular methods, sequencing and phylogenetic analysis were used to characterize the microbiota.

Results and Discussion

The microbiota in wild-caught Anopheles was diverse with the presence of 47 bacterial OTUs belonging to 30 genera, including bacterial genera impacting Plasmodium development. The bacteria were affiliated with 4 phyla, Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria, the latter being the dominant phylum. Four bacterial genera are newly described in Anopheles mosquitoes including Coxiella, Yersinia, Xanthomonas, and Knoellia. The bacterial diversity per specimen was low ranging from 1 to 4. The results show the importance of pairing culture and fingerprint methods to better screen the bacterial community in Anopheles mosquitoes.

Conclusion

Sampled Anopheles species from central-south Vietnam contained a diverse bacterial microbiota that needs to be investigated further in order to develop new malaria control approaches. The combination of both culture and DNA fingerprint methods allowed a thorough and complementary screening of the bacterial community in Anopheles mosquitoes.