Flavobacterium acetivorans sp. nov. and Flavobacterium galactosidilyticum sp. nov., psychrotolerant flavobacteria isolated from cultivated fish.

Two yellow-coloured strains, F-29T and F-340T, were isolated from fish farms in Antalya and Mugla in 2015 and 2017 during surveillance studies. The 16S rRNA gene sequence analysis showed that both strains belong to the genus Flavobacterium. A polyphasic approach involving a comprehensive genome analysis was employed to ascertain the taxonomic provenance of the strains. The overall genome-relatedness indices of digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) between the strains and the other members of the genus Flavobacterium were found to be well below the established thresholds of 70 and 95 %, respectively. The whole-genome-based phylogenetic analysis revealed that strain F-29T is closely related to Flavobacterium granuli (dDDH 39.3 % and ANI 89.4 %), while strain F-340T has a close relationship with the type strain of Flavobacterium pygoscelis (dDDH 25.6 % and ANI 81.5 %). Both strains were psychrotolerant with an optimum growth temperature of 25 °C. The chemotaxonomic characteristics of the strains were typical of the genus Flavobacterium. Both strains had phosphatidylethanolamine, aminolipids and unidentified lipids in their polar lipid profile and MK-6 as the isoprenoid quinone. The major fatty acids were iso-C15 : 0 and anteiso-C15 : 0. The genome size of the strains was 3.5 Mb, while G+C contents were 35.3 mol% for strain F-29T and 33.4 mol% for strain F-340T. Overall, the characterizations confirmed that both strains are representatives of two novel species within the genus Flavobacterium, for which the names Flavobacterium acetivorans sp. nov. and Flavobacterium galactosidilyticum sp. nov. are proposed, with F-29T (JCM 34193T=KCTC 82253T) and F-340T (JCM 34203T=KCTC 82263T) as the type strains, respectively.

Phylogenomic characterization of Flavobacterium psychrophilum isolates retrieved from Turkish rainbow trout farms.

Flavobacterium psychrophilum, a devastating fish pathogen, is responsible for bacterial cold-water disease (BCWD), also known as rainbow trout fry syndrome. F. psychrophilum is the main causative agent of outbreaks in rainbow trout farms, especially at early live stages. In the present study, we aimed to characterize F. psychrophilum Turkish isolates. Eighteen isolates were retrieved from BCWD outbreaks between 2014 and 2021. In vitro phenotypic characterization showed gelatin and casein hydrolysis capacities and in vitro adhesion for all isolates, whereas elastinolytic activity was present for 16 of 18 isolates. We used complete genome sequencing to infer MLST-type, serotype and phylogenetic reconstruction. Strikingly, one strain isolated from Coruh trout (FP-369) belongs to ST393, a previously undescribed ST, and is phylogenetically distant from the other isolates. However, all strains retrieved from rainbow trout belong to the well-characterized clonal complex CC-ST10, 12 of 17 were tightly connected in a single cluster. Several serotypes (Types -1, -2 and -3) were represented among isolates, but no correlation was observed with geographic origins. This analysis suggests a regional dissemination of an epidemic, disease-producing bacterial population. This study provides a basis for epidemiological surveillance of isolates circulating in Turkey and phenotypic data for future molecular studies of virulence traits of this important fish pathogen.

Genomic insight into Myroides oncorhynchi sp. nov., a new member of the Myroides genus, isolated from the internal organ of rainbow trout (Oncorhynchus mykiss).

The strain M-43T was isolated from the Oncorhynchus mykiss from a fish farm in Mugla, Turkey. Pairwise 16S rRNA gene sequence analysis was used to identify strain M-43T. The strain was a member of the genus Myroides sharing the highest 16S rRNA gene sequence identity levels of 98.7%, 98.3%, and 98.3% with the type strains of M. profundi D25T, M. odoratimimus subsp. odoratimimus CCUG 39352T and M. odoratimimus subsp. xuanwuensis DSM27251T, respectively. A polyphasic taxonomic approach including whole genome-based analyses was employed to confirm the taxonomic provenance of strain M-43T within the genus Myroides. The overall genome relatedness indices (OGRI) for strain M-43T compared with its most closely related type strains M. odoratimimus subsp. xuanwuensis DSM 27251T, M. profundi D25T, and M. odoratimimus subsp. odoratimimus ATCC BAA-634T, were calculated as 25.3%, 25.1%, and 25% for digital DNA-DNA hybridization (dDDH), 83.3%, 83.6%, and 83.4% for average nucleotide identity (ANI) analyses, respectively. The OGRI values between strain M-43T and its close neighbors confirmed that the strain represents a novel species in the genus Myroides. The DNA G + C content of the strain is 33.7%. The major fatty acids are iso-C15:0 and summed feature 9 (iso-C17:1 ω9c and/or 10-methyl C16:0). The predominant polar lipids are phosphatidylethanolamine, an amino-lipid and five unidentified lipids. The major respiratory quinone is MK-6. Chemotaxonomic and phylogenomic analyses of this isolate confirmed that the strain represents a novel species for which the name Myroides oncorhynchi sp. nov. is proposed, with M-43T as the type strain (JCM 34205T = KCTC 82265T).

Tentative Epidemiological Cut-Off Values and Distribution of Resistance Genes in Aquatic Pseudomonas Species Isolated from Rainbow Trout.

Epidemiological cut-off value (ECV) analysis for commonly used antimicrobials in aquaculture have not been established for many aquatic pathogens, including Pseudomonas. This study was the first to examine the categorization of 92 aquatic Pseudomonas isolates by calculating seven antimicrobials ECVs using two analytical methods: normalized resistance interpretation and ECOFFinder. Pseudomonas spp. isolates had decreased sensitivity to all antimicrobials examined except for doxycycline and ciprofloxacin. The PCR analysis of the 91 isolates of Pseudomonas spp. detected the tetracycline genes are predominant with the count of 41 genes, including tetA, tetC, tetD, tetM, tetS and tetH, following sulfonamide genes are in 21 isolates including sul1 and sul2, floR gene in 15 isolates and ermA gene in three isolates. Our findings provide an understanding of the antimicrobial categorization of Pseudomonas species, which are significant groups, subgroups, and species for aquaculture due to insufficiently defined breakpoints or cut-off values reported in CLSI and/or EUCAST.

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.

Shewanella oncorhynchi sp. nov., a novel member of the genus Shewanella, isolated from Rainbow Trout (Oncorhynchus mykiss).

A strain, S-1T was isolated from rainbow trout (Oncorhynchus mykiss) exhibiting clinical symptoms of lens atrophy, inappetence, visual impairment and growth retardation. The strain was identified as representing a member of the genus Shewanella on the basis of the results of 16S rRNA gene sequence analysis. The neighbor-joining phylogenetic tree based on 16S rRNA gene sequences indicated that S-1T clustered with Shewanella putrefaciens JCM 20190T, Shewanella profunda DSM 15900T, and Shewanella hafniensis P010T, sharing 99.3, 98.8 and 87.7% 16S rRNA gene similarities, respectively. A polyphasic taxonomic approach including phenotypic, chemotaxonomic, and genomic characterization was employed to ascertain the taxonomic position of S-1T within the genus Shewanella. The overall genome relatedness indices (OGRI) for S-1T compared with the most closely related type strains S. hafniensis ATCC BAA-1207T, Shewanella baltica NCTC 10735T, S. putrefaciens ATCC 8071T and S. profunda DSM 15900T were calculated as 40.8, 40.1, 28.5 and 27.3% for digital DNA-DNA hybridization (dDDH), and 91.6, 91.0, 86.3 and 85.1% for average nucleotide identity (ANI), respectively. OGRI values between S-1T and its close neighbours confirmed that the strain represents a novel species in the genus Shewanella.The DNA G+C content of the strain is 45.2%. Major fatty acids were C17 : 1ω8c, C15 : 0iso, and summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c). The predominant polar lipids were phosphatidylethanolamine, phospholipid, amino-phospholipid and unidentified lipids. The major respiratory quinones were ubiquinone-8, ubiquinone-7 and menaquinone-7. Chemotaxonomic and phylogenomic analyses of this isolate confirmed that the strain represents a novel species for which the name Shewanella oncorhynchi sp. nov. is proposed, with S-1T as the type strain (JCM 34183T= KCTC 82249T).

Flavobacterium muglaense sp. nov. isolated from internal organs of apparently healthy rainbow trout.

Two yellow-pigmented isolates, F-60T and F-392, were isolated from the internal organs of an apparently healthy rainbow trout (Oncorhynchus mykiss). The strains were identified as members of the genus Flavobacterium based on the results of 16S rRNA gene sequence analysis. Strains F-60T and F-392 had the highest 16S rRNA gene sequence identity level of 97.4 % to the type strain of Flavobacterium crassostreae LPB0076T. A polyphasic taxonomic approach including phenotypic, chemotaxonomic and genomic characterization was employed to ascertain the taxonomic position of the strains within the genus Flavobacterium. Digital DNA-DNA hybridization (dDDH) and average nucleotide identity based on blast (ANIb) values for strains F-60T and F-392 were calculated as 100 %. However, dDDH and ANI analyses between the strains and their close neighbours confirmed that both strains represent a novel species in the genus Flavobacterium. The strains shared the highest dDDH and ANIb levels of 23.3 and 77.9%, respectively, with the type strain of Flavobacterium frigidarium DSM 17623T while those values for F. crassostreae LPB0076T were obtained as 21.4-21.5 % and 76.3 %. The DNA G+C content of the strains was 34.5 mol%. Chemotaxonomic and phylogenomic analyses of these isolates confirmed that both strains are representatives of a novel species for which the name Flavobacterium muglaense sp. nov. is proposed, with F-60T as the type strain (=JCM 34196T=KCTC 82256T).

Pseudomonas arcuscaelestis sp. nov., isolated from rainbow trout and water.

Cells of strains P66T, V1 and W15Feb18 are Gram-stain-negative short rods and motile by one polar flagellum. Strain P66T was isolated from rainbow trout (Oncorhynchus mykiss) cultivated at a fish farm in Turkey. Strain V1 was isolated from sand of an intertidal shore on the Galicia coast in Spain and strain W15Feb18 was isolated from water collected at the Woluwe River in Belgium. Based on 16S rRNA sequence similarity values, the strains were grouped under the genus Pseudomonas and the Pseudomonas putida phylogenetic group of species. The DNA G+C content ranged from 58.5 to 58.9 mol%. The strains were characterized phenotypically by the API 20NE and Biolog GEN III tests, and chemotaxonomically by their whole-cell MALDI-TOF MS protein profiles and fatty acid contents. The absence of the hydrolysis of gelatin and the assimilation of arabinose, mannose and mannitol differentiated these strains from the closest species, Pseudomonas alkylphenolica. The major fatty acid components were C16:0 (29.91-31.68 %) and summed feature 3 (36.44-37.55 %). Multilocus sequence analysis with four and 83 housekeeping gene sequences and a core proteome analysis showed that these strains formed a phylogenetic cluster in the P. putida group of species. Genome comparisons by the average nucleotide identity based on blast and the Genome-to-Genome Distance Calculator demonstrated that the three strains belonged to the same genomic species and were distant from any known species, with similarity values lower than the thresholds established for species in the genus Pseudomonas. These data permitted us to conclude that strains P66T, V1 and W15Feb18 belong to a novel species in the genus Pseudomonas, for which the name Pseudomonas arcuscaelestis sp. nov. is proposed. The type strain is P66T (=CECT 30176T=CCUG 74872T). The other strains have been deposited in the CECT with the corresponding collection numbers: V1 (=CECT 30356) and W15Feb18 (=CECT 30355).

Goat semen cryopreservation with rainbow trout seminal plasma supplemented lecithin-based extenders.

The objective of this study was to determine the optimum concentrations of rainbow trout seminal plasma (RTS) supplemented extenders for goat semen quality at post-thaw and after incubation. Five sexually mature Saanen goat (Capra aegagrus hircus) were used for semen collection. Pooled semen was diluted with soybean lecithin-based extender without RTS (control) or supplemented with different concentrations of RTS (1%, 2%, 4% or 8%), at a final concentration of 150 × 106 spermatozoon/ml. Sperm motility, plasma membrane functional integrity (HOST), damaged acrosome (PSA-FITC), mitochondrial activity (rhodamine123) and DNA integrity (TUNEL) were evaluated. Spermatological parameters were evaluated at post-thaw and after 6 hr incubation. RTS8 group preserved sperm motility, acrosomal integrity, plasma membrane functional integrity and mitochondrial function better than the control group (p < .05). The study demonstrated that RTS supplemented lecithin-based extenders have useful effects on goat spermatozoa. In addition, the results of the current study represented the positive effect of using 8% RTS supplemented extender.

Pseudomonas piscium sp. nov., Pseudomonas pisciculturae sp. nov., Pseudomonas mucoides sp. nov. and Pseudomonas neuropathica sp. nov. isolated from rainbow trout.

Six Gram negative, motile bacteria were isolated from rainbow trout (Oncorhynchus mykiss). The 16S rRNA sequence similarity values grouped them in the Pseudomonas mandelii (strains P49, P50T, 154aT and P154b), Pseudomonas fluorescens (strain P115T) and Pseudomonas koreensis (strain P155T) phylogenetic subgroups in the genus Pseudomonas. The DNA G+C content ranged from 58.5 to 60 mol%. The strains were characterized phenotypically using API 20NE and Biolog GENIII tests, and chemotaxonomically by their whole-cell MALDI-TOF MS protein profiles and fatty acid contents. Multi-locus sequence analysis with four housekeeping gene sequences (rpoD, rpoB, gyrB and 16S rRNA) together with genome comparisons by average nucleotide identity and genome-to-genome distance calculations were performed. Results showed that the similarity values of these strains to known species type strains were lower than the thresholds established for species in the genus Pseudomonas. Based on these data, we concluded that strains P49, P50T, P115T, P154aT, P154b and P155T belonged to four novel species. The names proposed are: Pseudomonas piscium sp. nov. for strains P49 and P50T with P50T (=CECT 30175T=CCUG 74871T) as the type strain; Pseudomonas pisciculturae sp. nov. for strain P115T (CECT 30173T=CCUG 74873T); Pseudomonas mucoides sp. nov. for strains P154aT and P154b with P154aT (=CECT 30177T=CCUG 74874T) as the type strain; and Pseudomonas neuropathica sp. nov. for strain P155T (=CECT 30178T=CCUG 74875T).

Antimicrobial resistance and molecular characterization of Pantoea agglomerans isolated from rainbow trout (Oncorhynchus mykiss) fry.

Aquaculture has become an important candidate as an animal protein source through its growth over the last decade. Based upon a report from the Food and Agriculture Organization of the United Nations, it is the fastest growing sector of the food industry, yet the pathogenicity of many biological agents involved in aquaculture is still unknown. In this study, we isolated Pantoe agglomerans from diseased rainbow trout on several occasions and also attempted to determine their phenotypic and genotypic characteristics, including antimicrobial resistance, of four bacterial isolates. In the present study, P. agglomerans was isolated from diseased rainbow trout as a pathogenic agent. The identification of the P. agglomerans isolates from the rainbow trout was performed through biochemical tests and 16S rRNA sequence analysis. These isolates were predominately biochemically homogeneous, although some features were different, such as seen in methyl-red, mannose and lipase activity tests. All four studied isolates were identified as 99% identical to P. agglomerans based on sequence analysis. The isolates were compared through a phylogenetic analysis with P. agglomerans sequences recovered from 16 other countries and accessed from the GenBank database. All isolates in our study were at least 98.2% similar to sequences from GenBank. Furthermore, the phenotypic antimicrobial susceptibility of the isolates in this study was analyzed through both disc diffusion and broth micro dilution minimum inhibitory concentration (MIC) tests. Although there were some differences between two phenotypic antimicrobial tests, all studied isolates were found susceptible to different antimicrobials. In addition genotypic antimicrobial resistance characteristics were assessed by the presence of antimicrobial resistance genes (ARGs), in which qnrS and sul2 were detected for the first time in P. agglomerans.

The determination of the infectious status and prevalence of motile Aeromonas species isolated from disease cases in rainbow trout (Oncorhynchus mykiss) and aquarium fish.

The aims of this study were to determine the prevalence and phylogenetic relationship of motile Aeromonas spp. that might be pathogenic species for rainbow trout in infected/mix infection cases (based upon different outbreaks on fish farms). A total of 99 motile Aeromonas isolates (and three reference strains) were analysed that were isolated from four different fish species in different sizes of fish (0.1-3,000 g), different months and water temperatures (6.1-21.2°C). The biochemical characteristics of the isolates were determined using conventional tests and a rapid test kit. Additionally, molecular identification was performed using the gyrB housekeeping gene region and with glycerophospholipid-cholesterol acyltransferase polymerase chain reaction (GCAT-PCR). The sequencing results obtained from the gyrB gene region were deposited in the GenBank database, and phylogenetic relationships were determined with the BioNumerics 7.6 database. Nearly half of the Aeromonas isolates that were isolated from rainbow trout showing signs of disease were determined to be possible infectious agents. Aeromonas species exhibit biochemical variability for many characters, so some Aeromonas species tested negative for GCAT-PCR despite that this test was created especially for Aeromonas identification. The phylogenetic tree based upon gyrB contained 10 different phylogroups that were based on 96% cut-off value in gyrB gene region.

Genotyping and antimicrobial resistance genes of Yersinia ruckeri isolates from rainbow trout farms.

In this study, we compared 142 Yersinia ruckeri isolates collected between 2013 and 2016 from 6 different regions in Turkey. A total of 18 different genogroups were found, though most of the isolates clustered into the same genogroup as serotype O1. As immunization of fish with inactivated Y. ruckeri by injection, immersion, or feeding provide minimal protection against Y. ruckeri infection in Turkey, many fish producers use antimicrobials unrestrictedly, resulting in antimicrobial resistance in aquatic pathogens. Accordingly, we investigated resistance to the antimicrobials most commonly used to treat yersiniosis. More than 80% of the Y. ruckeri isolates were susceptible to sulfamethoxazole-trimethoprim (SXT), florfenicol (FFC), and tetracycline, whereas none were susceptible to sulfamethoxazole. The most commonly used antimicrobials (SXT and FFC) can be effectively administered because the resistance levels to these drugs are the lowest among those reported for agents used to control enteric red mouth disease (12.6 and 14.7%, respectively). In conclusion, to the best of our knowledge, this study is the first characterization of the antimicrobial resistance genes floR, sulI, tetC, tetD, and tetE in Y. ruckeri isolates from aquaculture. Additionally, we detected the sulII gene but not the tetA, tetB, tetM, tetS, or sulIII genes.

Expanding the Spectrum of Diseases and Disease Associations Caused by Edwardsiella tarda and Related Species.

The genus Edwardsiella, previously residing in the family Enterobacteriaceae and now a member of the family Hafniaceae, is currently composed of five species, although the taxonomy of this genus is still unsettled. The genus can primarily be divided into two pathogenic groups: E. tarda strains are responsible for almost all human infections, and two other species (E. ictaluri, E. piscicida) cause diseases in fish. Human infections predominate in subtropical habitats of the world and in specific geospatial regions with gastrointestinal disease, bloodborne infections, and wound infections, the most common clinical presentations in decreasing order. Gastroenteritis can present in many different forms and mimic other intestinal disturbances. Chronic gastroenteritis is not uncommon. Septicemia is primarily found in persons with comorbid conditions including malignancies and liver disease. Mortality rates range from 9% to 28%. Most human infections are linked to one of several risk factors associated with freshwater or marine environments such as seafood consumption. In contrast, edwardsiellosis in fish is caused by two other species, in particular E. ictaluri. Both E. ictaluri and E. piscicida can cause massive outbreaks of disease in aquaculture systems worldwide, including enteric septicemia in channel catfish and tilapia. Collectively, these species are increasingly being recognized as important pathogens in clinical and veterinary medicine. This article highlights and provides a current perspective on the taxonomy, microbiology, epidemiology, and pathogenicity of this increasingly important group.

A Review of the Industrial Importance, Common Bacterial Diseases, and Zoonotic Risks of Freshwater Aquarium Fish.

Background: The ever-increasing popularity of home aquariums, most often involving freshwater varieties, has exploded in recent years partially due to the Coronavirus pandemic and related to stay-at-home public health precautions for social distancing. With this ever-increasing popularity of aquariums as a hobby, and whether this involves freshwater or marine fish species, a number of important economic, ecological, and public health issues arise for both fish and hobbyists alike. Materials and Methods: This review highlights the history and genesis of aquariums as both a hobby and an important economic factor (industrial, commercial) for many countries on a global basis. Types of aquarium fish are described, and culture conditions leading to homeostasis in aquatic environments are detailed. When these conditions are not met and aquatic systems are out of balance, the disease can result due to stressed fish. Results: Major bacterial diseases associated with freshwater aquarium fish are reviewed, as are potential human infections related to the care and maintenance of home aquaria. Conclusion: Besides, scientific information was also combined with the false facts of hobbyists who tried to identify and treat diseases during an outbreak in the aquarium. Finally, unresolved issues and important misconceptions regarding the field are discussed.

Molecular Characterization and Antibacterial Resistance Determination of Escherichia coli Isolated from Fresh Raw Mussels and Ready-to-Eat Stuffed Mussels: A Major Public Health Concern.

Our study focused exclusively on analyzing Escherichia coli (E. coli) contamination in fresh raw mussels and ready-to-eat (RTE) stuffed mussels obtained from authorized and regulated facilities. However, it is critical to recognize that such contamination represents a significant public health threat in regions where unauthorized harvesting and sales practices are prevalent. This study aimed to comprehensively assess the prevalence, molecular characteristics, and antibacterial resistance profiles of E. coli in fresh raw mussels and RTE stuffed mussels. E. coli counts in fresh raw mussel samples ranged from 1 to 2.89 log CFU/g before cooking, with a significant reduction observed post-cooking. RTE stuffed mussel samples predominantly exhibited negligible E. coli presence (<1 log CFU/g). A phylogenetic analysis revealed a dominance of phylogroup A, with variations in the distribution observed across different sampling months. Antibacterial resistance was prevalent among the E. coli isolates, notably showing resistance to ampicillin, streptomycin, and cefotaxime. Extended-spectrum ß-lactamase (ESßL) production was rare, with only one positive isolate detected. A variety of antibacterial resistance genes, including tetB and sul1, were identified among the isolates. Notably, virulence factor genes associated with pathogenicity were absent. In light of these findings, it is imperative to maintain rigorous compliance with quality and safety standards at all stages of the mussel production process, encompassing harvesting, processing, cooking, and consumption. Continuous monitoring, implementation of rigorous hygiene protocols, and responsible antibacterial drug use are crucial measures in mitigating food safety risks and combating antibacterial resistance. Stakeholders, including seafood industry players, regulatory agencies, and healthcare professionals, are essential to ensure effective risk mitigation and safeguard public health in the context of seafood consumption.

Comprehensive genome analysis of five novel flavobacteria: Flavobacterium piscisymbiosum sp. nov., Flavobacterium pisciphilum sp. nov., Flavobacterium flavipigmentatum sp. nov., Flavobacterium lipolyticum sp. nov. and Flavobacterium cupriresistens sp. nov.

Eight isolates were obtained through a study on culture-dependent bacteria from fish farms and identified as members of the genus Flavobacterium based on pairwise analysis of the 16S rRNA gene sequences. The highest pairwise identity values were calculated as 98.8 % for strain F-30 T and Flavobacterium bizetiae, 99.0 % for strain F-65 T and Flavobacterium branchiarum, 98.7 % for strain F-126 T and Flavobacterium tructae, 98.2 % for strain F-323 T and Flavobacterium cupreum while 99.7 % identity level was detected for strain F-70 T and Flavobacterium geliluteum. In addition, strains F-33, Fl-77, and F-70 T shared 100 % identical 16S rRNA genes, while strains F-323 T and Fl-318 showed 99.9 % identity. A polyphasic approach including comparative analysis of whole-genome data was employed to ascertain the taxonomic provenance of the strains. In addition to the morphological, physiological, biochemical and chemotaxonomic characteristics of the strains, the overall genome-relatedness indices of dDDH and ANI below the established thresholds confirmed the classification of the strains as five novel species within the genus Flavobacterium. The comprehensive genome analyses of the strains were also conducted to determine the biosynthetic gene clusters, virulence features and ecological distribution patterns. Based on the polyphasic characterisations, including comparative genome analyses, it is concluded that strains F-30 T, F-65 T, F-70 T, F126T and F-323 T represent five novel species within the genus Flavobacterium for which Flavobacterium piscisymbiosum sp. nov. F-30 T (=JCM 34194 T = KCTC 82254 T), Flavobacterium pisciphilum sp. nov. F-65 T (=JCM 34197 T = KCTC 82257 T), Flavobacterium flavipigmentatum sp. nov. F-70 T (Fl-33 = Fl-77 = JCM 34198 T = KCTC 82258 T), Flavobacterium lipolyticum sp. nov. F-126 T (JCM 34199 T = KCTC 82259 T) and Flavobacterium cupriresistens sp. nov. F-323 T (Fl-318 = JCM 34200 T = KCTC 82260 T), are proposed.

Description of three new Pseudomonas species isolated from aquarium fish: Pseudomonas auratipiscis sp. nov., Pseudomonas carassii sp. nov. and Pseudomonas ulcerans sp. nov.

Pseudomonas species constitute a significant group of pathogens in aquarium fish and frequently cause haemorrhagic septicaemia. This study conducted a taxonomic characterization of Pseudomonas isolates from aquarium fish exhibiting deep ulceration and general disease signs. A polyphasic approach was employed to ascertain the taxonomic affiliation of the strains. The overall genome relatedness indices of digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) between the strains and the other members of the genus Pseudomonas were found to be below the established thresholds of 70 and 95-96%, respectively. Whole-genome based phylogenetic analysis revealed that strains 119PT and 120P were closely related to P. arcuscaelestis. Strain 137PT was related to P. peradeniyensis, while strains 147PT and 148P were closely related to P. japonica. The morphological, physiological, and biochemical characteristics of the strains and the genome relatedness indices of dDDH and ANI below the established thresholds confirmed the classification of the strains as three novel species. Genome analyses of the strains were also conducted to determine their biosynthesis-related gene clusters, virulence features and ecological distribution patterns. Based on polyphasic characterization, the strains 119PT, 120P, 137PT, 147PT, and 148P are novel species within the genus Pseudomonas, for which the following names are proposed: Pseudomonas auratipiscis sp. nov., with the strain 119PT as the type strain (=DSM 117162 T, =LMG 33381T); Pseudomonas carassii sp. nov., with the strain 137PT as the type strain (=DSM 117060T, =LMG 33378T); and Pseudomonas ulcerans sp. nov. 147PT, as the type strain (=DSM 117163T, =LMG 33377T).

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-17T, C-39T 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-17T shared the highest identity level of 98.1 % with the type strain of Chryseobacterium piscium LMG 23089T while strains C-2, C-39T and Ch-15 were closely related to Chryseobacterium balustinum DSM 16775T 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-17T, C-39T and Ch-15 formed two novel species within the genus Chryseobacterium. Chemotaxonomic analyses showed that strains C-17T and C-39T 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-C15:0 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-17T and C-39T 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-17T (=JCM 34190T = KCTC 82250T) and C-39T (=JCM 34191T = KCTC 822251T), respectively, are proposed.