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

Three strains (VPAP16, VPAP18 and VPAP23 strains) were isolated as the most predominant organisms from 3 different episodes of massive mortalities of larval cultures of the Chilean scallop Argopecten purpuratus occurred in different commercial hatcheries located in northern Chile. The main aims of this study were to identify the pathogenic strains and investigate their pathogenic activity. Based on selected phenotypic features and sequence identity of the 16S rRNA gene and the housekeeping gene, RNA polymerase α-chain rpoA , all pathogenic strains were identified as Vibrio splendidus . Healthy 10 – day – old scallop larvae cultures exhibited mortality percentages of 69.61 ± 3.35%, 79.78 ± 6.11% and 61.73 ± 3.71% after 48 h when were inoculated with 1 × 10 6 CFU (colony forming units) mL −1 of VPAP16, VPAP18 and VPAP23 strains, respectively, and evidenced that concentrations ⩾10 4 CFU mL −1 would probably be detrimental for the larval culture. The main clinical signs observed in challenged larvae for 24 h were bacterial swarms on the margins of the larvae, extension and disruption of the velum, detachment of velum cilia cells and digestive tissue necrosis. Otherwise, challenge assays using pathogenic strains stained with 5-([4,6-dichlorotriazin-2-yl]amino)fluorescein hydrochloride (5-DTAF) evidenced that after 1 h stained bacteria were detected in high density in the digestive gland and the margin of the shell. When larval cultures were inoculated with cell-free extracellular products (ECP) of V. splendidus strains, exhibited larval mortalities higher than 70% (VPAP16), 80% (VPAP18) and 50% (VPAP23) after 24 h, even when ECP were treated with proteinase K or heat, indicating that extracellular pathogenic activity is mainly mediated by non-proteic thermostable compounds. In this study all Koch’s postulates were fulfilled and it was demonstrated for the first time the pathogenic activity of V. splendidus strains on reared-larvae of scallop A. purpuratus and prompt the necessity to maintain this species at concentrations lower than 10 4 CFU mL −1 to avoid episodes of mass mortalities in scallop hatcheries. [ABSTRACT FROM AUTHOR]

The administration of antimicrobials to control bacterial pathologies in Chilean scallop hatcheries is a frequent practice, but their effects on these cultures remained unknown. This study was undertaken to obtain information on the effect of the administration of florfenicol and oxytetracycline on the growth, survival and bacterial content of scallop larvae under farming conditions. Florfenicol-treated cultures exhibited high survival rates (44% after 17 days of culture), whereas cultures not treated or treated with oxytetracycline collapsed after 11 days of culture. Surprisingly, no significant differences in the heterotrophic (Tukey test; P = 0.226) and Vibrio (Tukey test; P = 0.666) concentrations between the oxytetracycline-treated and untreated larval cultures were observed. Otherwise, florfenicol administered directly into rearing tanks produced significantly higher larval growth (Tukey test; P = 0.0001) and survival (Tukey test; P = 0.011) than bath treatment. When 2 and 4 mg L−1 of florfenicol were compared, no significant differences in growth ( t-test; P = 0.4596) and survival (Tukey test; P = 0.057) were observed, suggesting that a concentration of 2 mg L−1 is sufficient to ensure larval production. The present results demonstrate the efficacy of florfenicol-based therapy to increase larval survival and growth at commercial scale and prompt the necessity to standardize its use in Chilean scallop hatcheries. [ABSTRACT FROM AUTHOR]

Mass mortalities of larval cultures of Chilean scallop Argopecten purpuratus have repeatedly occurred in northern Chile, characterized by larval agglutination and accumulation in the bottom of rearing tanks. The exopolysaccharide slime (EPS) producing CAM2 strain was isolated as the primary organism from moribund larvae in a pathogenic outbreak occurring in a commercial hatchery producing larvae of the Chilean scallop Argopecten purpuratus located in Bahía Inglesa, Chile. The CAM2 strain was characterized biochemically and was identified by polymerase chain reaction amplification of 16S rRNA as Halomonas sp. (Accession number DQ885389.1). Healthy 7-day-old scallop larvae cultures were experimentally infected for a 48-h period with an overnight culture of the CAM2 strain at a final concentration of ca. 105 cells per milliliter, and the mortality and vital condition of larvae were determined by optical and scanning electron microscopy (SEM) to describe the chronology of the disease. Pathogenic action of the CAM2 strain was clearly evidenced by SEM analysis, showing a high ability to adhere and detach larvae velum cells by using its “slimy” EPS, producing agglutination, loss of motility, and a posterior sinking of scallop larvae. After 48 h, a dense bacterial slime on the shell surface was observed, producing high percentages of larval agglutination (63.28 ± 7.87%) and mortality (45.03 ± 4.32%) that were significantly ( P < 0.05) higher than those of the unchallenged control cultures, which exhibited only 3.20 ± 1.40% dead larvae and no larval agglutination. Furthermore, the CAM2 strain exhibited a high ability to adhere to fiberglass pieces of tanks used for scallop larvae rearing (1.64 × 105 cells adhered per square millimeters at 24 h postinoculation), making it very difficult to eradicate it from the culture systems. This is the first report of a pathogenic activity on scallop larvae of Halomonas species, and it prompts the necessity of an appraisal on biofilm-producing bacteria in Chilean scallop hatcheries. [ABSTRACT FROM AUTHOR]

Abstract: In Chile, the administration of florfenicol to control bacterial pathologies in freshwater salmon farms is a frequent practice, but no studies has been developed to evaluate the incidence of florfenicol-resistant bacteria in these cultures. This study was undertaken to obtain information on the occurrence of florfenicol-resistant bacteria in a farm (LF1) under florfenicol therapy two weeks before sampling date, located in the Rupanco Lake, and a farm (LF2) with no recent history of antibacterial therapy, located in the Llanquihue Lake. Samples from surface water, pellet, Salmo salar fingerlings and control and under-cage sediments were collected from each salmon farm. Total and florfenicol-resistant culturable counts were determined by a spread plate method, observing low (<9%) proportions of florfenicol resistance in water and fingerling samples, whereas sediment samples from LF1 farm showed proportions ranging from 18.55±2.85% (control) to 26.40±1.56% (under-cage) and were significantly higher (P <0.05) than those from LF2 farm, with 0.29±0.30% (control) and 0.69±1.00% (under-cage) values, not observing a direct correlation with sediment organic enrichment. Also, unmedicated pelletized feed from LF1 farm showed high levels of resistance (34.79±11.87%), and were significantly (P <0.05) higher than those from LF2 farm (<0.001%). A number of 34 and 36 representative isolates recovered from LF1 and LF2 farms respectively, were selected and identified by using the Biolog Microbial ID System, observing that mainly belonged to Pseudomonas genus (67.65 and 66.67% in LF1 and LF2 farms) and the predominant species were P. putida and P. viridilivida (14.71%) in LF1 farm, and P. fluorescens (36.11%) in LF2 farm. Antibacterial susceptibility patterns of resistant strains from both Lakes were similar, showing important proportions of isolates resistance to ampicillin, erythromycin, furazolidone and cotrimoxazole and susceptibility to gentamicin, kanamycin and enrofloxacin. The minimum inhibitory concentration (MIC) of florfenicol against these selected bacteria were determined, observing MIC ranges of 256–>1024 and 64–>1024 μg ml−1 for strains recovered from LF1 and LF2 farms, respectively. The important occurrence of florfenicol-resistant and antibacterial-multiresistant microorganisms in unpolluted and farm-impacted sites in Rupanco Lake suggests that use of florfenicol is not a necessary causal condition for the development of elevated frequencies of florfenicol resistance. Otherwise, considering that intrinsic resistance to many antibacterials has been extensively reported for Pseudomonas species, observed levels of resistance to florfenicol could be overestimated by the occurrence of innately resistant bacteria with multiple non-specific resistances. Our results prompt the necessity for maintaining a continuous surveillance of florfenicol resistance in salmon farms, as well as to characterize the molecular elements involved in these resistances to evaluate the feasibility of their dissemination among environmental microbiota. [Copyright &y& Elsevier]

The use of oxytetracycline for preventing and controlling bacterial pathogens in salmon farming is frequent in Chile, yet no studies have been performed to evaluate the ecological impact of its intensive and prolonged use. In this work, the frequency of oxytetracycline-resistant bacteria from water, pelletized feed and fingerlings from four Chilean freshwater Atlantic salmon farms, as well as the level of resistance of selected strains was investigated. Viable bacterial counts were performed by a spread plate method and antibiotic-resistant bacteria were counted in culture media supplemented with the selected antibiotic. Resistance levels of selected strains isolated in media containing antibiotic were determined using an agar plate dilution method. High proportions of low- and high-level oxytetracycline-resistant bacteria (selected in agar plates containing 30 and 100 μg/ml, respectively), mainly from pelletized feed and effluent samples of the fish farms were found. The highest proportions of resistant bacteria were found in the effluent samples, and were significantly higher (P<0.05, Tukey''s test) than those from the other samples studied. On the contrary, influent samples exhibited the lowest proportions of resistant bacteria. One hundred and three resistant Gram-negative isolates, which represented the oxytetracycline-resistant bacterial population, were randomly selected on TSA containing 30 or 100 μg/ml of oxytetracycline, from salmon farms and pellet samples, and streaked for purification on TSA plates without oxytetracycline. A large number of non-fermenting bacteria (77.7%) were identified. Among these, Pseudomonas fluorescens (28.2%), Stenotrophomonas maltophilia (5.8%), Sphingomonas paucimobilis (5.8%), Acinetobacter lwoffii (4.8%), and Pseudomonas putida (4.8%) were the most frequent. Also, an important number of strains of Aeromonas hydrophila (9.7%), Burkholderia cepacia (3.9%), Brevundimonas vesicularis (3.9%), Acinetobacter johnsonii (2.9%), Pantoea sp. (2.9%) and Moraxella sp. (2.9%) were found. P. fluorescens and A. hydrophila predominated in salmon fingerlings, whereas A. lwoffii and S. maltophilia were predominant in pellet samples. Selected strains exhibited high levels of oxytetracycline resistance, with minimum inhibitory concentrations (MICs) ranging from 64 to 2048 μg/ml, whereas MIC90 of oxytetracycline varied between 1024 and 2048 μg/ml. This study shows the presence of an important population of oxytetracycline-resistant bacteria in the microflora of Chilean salmon farms. Therefore, the environment of these farms might play important roles as reservoirs of bacteria carrying genetic determinants for high-level tetracycline resistance, prompting an important risk to public health for workers involved in fish culturing and processing. [Copyright &y& Elsevier]

The intensive use of antimicrobial agents, mainly oxytetracycline, to prevent and control bacterial pathologies in Chilean salmon culture is a frequent practice. A total of 103 Gram-negative oxytetracycline-resistant bacteria recovered from various sources of 4 Chilean freshwater salmon farms were identified and investigated for their susceptibility patterns to various antibacterial agents, by using an agar disk diffusion method. Antibacterial resistance patterns of isolates were not correlated with bacterial species or strain source. A high number of bacteria resistant to amoxicillin, ampicillin, erythromycin, and furazolidone, as well as an important frequency of bacterial resistance to florfenicol, chloramphenicol, cefotaxime and trimethoprim-sulfamethoxazole was found. On the contrary, the proportion of bacteria resistant to gentamicin, kanamycin, flumequine and enrofloxacin was rather low. Resistant microflora showed a high taxonomic variability and mainly consisted of non-fermenting bacteria (77.7%). These strains mainly belonged to the species Pseudomonas fluorescens (29), Aeromonas hydrophila (10), Stenotrophomonas maltophilia (6), isolated from salmon fingerlings, and Acinetobacter lwoffii (5) isolated from pelletized feed. The occurrence of simultaneous resistance to various antibacterials was frequent. We observe a high frequency of bacteria resistant to 6–10 antibacterials (74 strains), and antibiotic resistance index (ARI) values ranging from 0.38 to 0.48 for the four salmon farms studied. These results suggest that Chilean salmon farms might play a role as reservoirs of antibacterial multiresistant bacteria, thus prompting the necessity for a more restrictive attitude towards the intensive use of antibacterials in salmon farming. [Copyright &y& Elsevier]

Flavobacteriosis, caused by Flavobacterium psychrophilum is considered the most important bacterial disease in Chilean freshwater salmonid farming, and is currently mainly controlled by the use of antimicrobial agents. The aim of this study was to correlate the results obtained by disk diffusion and minimum inhibitory concentration (MIC) assays of antimicrobials used in fish farming using F. psychrophilum isolates recovered from Chilean farmed salmonids. Antimicrobial susceptibility patterns and MIC values of six antibacterial agents against 125 Chilean isolates of F. psychrophilum were tested on Diluted (1:5) Cation-Adjusted Mueller-Hinton (DCAMH) agar using a disk diffusion method and an agar dilution method, respectively. A moderate correlation for antimicrobials amoxicillin and florfenicol was observed (Pearson correlation indices of −0.6894 and −0.5857, respectively), whereas highly significantly high (p <.001) correlations were detected for oxytetracycline, oxolinic acid, flumequine and enrofloxacin (Pearson correlation indices of −0.7901, −0.8386, −0.8151 and −0.7818, respectively), demonstrating that MIC and disk values were tightly associated (R2 ≥ 0.61). When isolates were categorized as fully susceptible Wild-Type or Non Wild-Type, the number of isolates differently categorized using each method varied between 8 and 23 for assayed antibacterials. The use of DCAMH without biological supplements was efficient to perform agar dilution tests with F. psychrophilum but its use to perform disk diffusion assays is questionable, due to some isolates exhibiting poor growth produced inhibition zones that are difficult to read. This study demonstrates that the agar dilution method is a good alternative to determine MIC values when a high number of isolates must be assayed. In contrast, further research is required to advance in the standardization of a disk diffusion procedure for this pathogen. • Disk diffusion and MIC values of oxytetracycline and quinolones of F. psychrophilum were significantly (p <.001) correlated • Lower correlations between disk diffusion and MIC values of amoxicillin and florfenicol of F. psychrophilum were shown. • Diluted Mueller-Hinton without biological supplements is efficient to perform agar dilution tests of Chilean F. psychrophilum. • Agar dilution method is a good alternative to determine MIC values when a high number of F. psychrophilum strains are assayed. [ABSTRACT FROM AUTHOR]

Simple Summary: The culture of the marine fish red cusk eel Genypterus chilensis is currently considered a priority for Chilean aquaculture but low larval survival rates have prompted the need for the continuous use of antibiotics, mainly florfenicol. In this study, the role of live prey (rotifers and the brine shrimp Artemia franciscana) used to feed fish larvae as a source of antibacterial-resistant bacteria in a commercial culture of G. chilensis was investigated. Samples of live feeds were collected during the larval growth period and their bacterial contents were determined. High levels of potentially opportunistic pathogens, such as Vibrio spp., as well as florfenicol-resistant bacteria, were detected. Sixty-five florfenicol-resistant isolates were recovered from these cultures and identified as Vibrio (81.5%) and Pseudoalteromonas (15.4%), which exhibited a high incidence of co-resistance to the antibiotics streptomycin, oxytetracycline, co-trimoxazole, and kanamycin. The majority of them carried the florfenicol-resistance encoding genes floR and fexA. The high prevalence of antibiotic-resistant bacteria and the associated genetic elements in live feed administered to reared fish larvae requires the prompt implementation of efficient management strategies to prevent future therapy failures in fish larval cultures and the spread of antibiotic-resistant bacteria to associated aquatic environments. The culture of red cusk eel Genypterus chilensis is currently considered a priority for Chilean aquaculture but low larval survival rates have prompted the need for the continuous use of antibacterials. The main aim of this study was to evaluate the role of live feed as a source of antibacterial-resistant bacteria in a commercial culture of G. chilensis. Samples of rotifer and Artemia cultures used as live feed were collected during the larval growth period and culturable bacterial counts were performed using a spread plate method. Rotifer and Artemia cultures exhibited high levels of resistant bacteria (8.03 × 104 to 1.79 × 107 CFU/g and 1.47 × 106 to 3.50 × 108 CFU/g, respectively). Sixty-five florfenicol-resistant isolates were identified as Vibrio (81.5%) and Pseudoalteromonas (15.4%) using 16S rRNA gene sequence analysis. A high incidence of resistance to streptomycin (93.8%), oxytetracycline (89.2%), co-trimoxazole (84.6%), and kanamycin (73.8%) was exhibited by resistant isolates. A high proportion of isolates (76.9%) carried the florfenicol-resistance encoding genes floR and fexA, as well as plasmid DNA (75.0%). The high prevalence of multiresistant bacteria in live feed increases the incidence of the resistant microbiota in reared fish larvae, thus proper monitoring and management strategies for live feed cultures appear to be a priority for preventing future therapy failures in fish larval cultures. [ABSTRACT FROM AUTHOR]

ABSTRACT Studies on preventing antimicrobial resistance in aquaculture emphasise the need to responsibly and prudently use antimicrobials, selecting those most effective in controlling and/or reducing mortalities caused by vibriosis. In this study, the distribution of the antimicrobial susceptibility of 28 Vibrio anguillarum isolates from Turkish fish farms was determined using the broth microdilution minimum inhibitory concentration (MIC) test according to the Clinical and Laboratory Standards Institute (CLSI) guideline. The epidemiological cut‐off (COWT) values of the V. anguillarum isolates of florfenicol (FLO), tetracycline (TET), doxycycline (DOX), oxolinic acid (OXO), enrofloxacin (ENR) and trimethoprim/sulfamethoxazole (SXT) were calculated using the normalised resistance interpretation (NRI) and ECOFFinder methods. Isolates were categorised as belonging to the fully susceptible wild‐type (WT) or non‐wild‐type (NWT) populations. Calculated COWT values (in μg mL−1) were ≤ 1.0 for FLO and DOX, ≤ 0.5 for TET, ≤ 0.016 for ENR, ≤ 0.032 for OXO, and ≤ 4.0 for SXT using the NRI analysis. Percentages of V. anguillarum isolates categorised as belonging to the NWT population were small for the antimicrobials FLO (10.7%) and SXT (0%), whereas they were higher for the antimicrobials OXO (39.3%) and ENR (39.3%). This is the first study to estimate the local COWT values for antibiotics used in the control of V. anguillarum isolates recovered from farmed fish in Turkey. [ABSTRACT FROM AUTHOR]

In an aquaponic system, fish and plants are cultivated together in a symbiotic environment where they mutually benefit, using significantly less water than traditional farming methods. The main aim of this study was to investigate the occurrence of antimicrobial resistance in two aquaponic systems implemented in two Chilean high schools using rainbow trout and lettuce cultures. When water samples (fish tank, biofilter, and plant raft) were analyzed over a three-month period, no resistance to oxytetracycline was detected, whereas the occurrence of resistance to florfenicol was rather small, ranging from 0.01% to 3.1% of bacterial culturable counts. Eighteen isolates were recovered from various sources as representatives of the florfenicol-resistant population, and all of them belonged to the Pseudomonas genus, showing a multi-drug-resistance phenotype and exhibiting simultaneous resistance to 7–13 antimicrobials. All isolates exhibited resistance to amoxicillin, chloramphenicol, florfenicol, and furazolidone and susceptibility to meropenem, oxytetracycline, oxolinic acid, flumequine, ciprofloxacin, and enrofloxacin. Five and two isolates carried the amphenicol-resistance-encoding genes floR and cmlA, respectively, whereas no carriage of integrons or the fexA, fexB, pexA, optrA, and cfr genes encoding for florfenicol resistance was detected. Eleven isolates carried plasmids, but only two of them were able to transfer their plasmid content by conjugation. The knowledge of the microbiome associated with aquaponic systems is still scarce, and their role as potential reservoirs of antimicrobial-resistant bacteria and related genes of these systems must be elucidated. [ABSTRACT FROM AUTHOR]

Aquaculture settings present a number of surfaces that can potentially act as a reservoir for Flavobacterium psychrophilum , resulting in a serious threat to the health of farmed salmonids. The aim of this study was to employ the CDC Biofilm Reactor to evaluate the capacity of F. psychrophilum to form biofilms on stainless steel, polystyrene, polyurethane, and polycarbonate. Scanning electron microscopy and confocal laser scanning microscopy were used to assess biofilm formation, while epifluorescence and qPCR methods were effectively used to determine cell contents. After a 72 h incubation period, F. psychrophilum had formed mature biofilms composed by dense, multilayered clusters of short bacilli on stainless steel, polystyrene, and polycarbonate. Nevertheless, biofilms formed on stainless steel presented a significantly higher cell density than those formed on polyurethane. Biofilm growth was poor on polyurethane surfaces. These findings will facilitate the design of appropriate guidelines for more efficiently managing F. psychrophilum and controlling the persistence of this pathogen in fish-farming environments. [ABSTRACT FROM AUTHOR]

Culture of red cusk eel Genypterus chilensis is currently considered a priority for Chilean aquaculture, but low larval survival rates mainly because of bacterial infections, prompted the need of a continuous use of antibacterial agents. It must be noted that use of antibiotics to treat live feed used in fish larval culture is frequent, so it is expected the occurrence of selection and spread of drug-resistant bacteria to reared fish larvae, precluding the success of a high-scale culture. The main aim of the study was to evaluate the role of live feed as source of antibacterial resistant bacteria in a commercial of the red cusk eel Genypterus chilensis larvae. Samples of rotifer and Artemia cultures, currently used as live feed in a commercial hatchery located in northern Chile were collected. Untreated and treated with florfenicol or oxytetracycline live feed cultures were sampled and total and resistant culturable counts were performed by a spread plate method. Rotifer and Artemia cultures exhibited high levels of culturable counts (7.1×10^7 CFU/g to 2.6×10^8 CFU/g, and 8.1×10^6 CFU/g to 6.1×10^7 CFU/g, respectively). Percentages of resistance to florfenicol and oxytetracycline ranged from 1.3% to 9.4% and 4.0 to 38.6%, respectively, in rotifer cultures, whereas in Artemia cultures varied from 5.1% to 19.1% and 22.1 to 43.0%, respectively. A number of 55 and 50 antibacterialresistant strains was isolated from rotifer and Artemia cultures, respectively, and identified by 16S rRNA gene sequence analysis, observing a predominance of the Vibrio (83.6% and 76.0%) and Pseudoalteromonas (14.5% and 20.0%) genera. Isolates exhibited a high incidence of resistance to streptomycin (92%), oxytetracycline (85%), florfenicol (78%), co-trimoxazole (67%) and amoxicillin (52%), whereas resistance to flumequine (33%) and oxolinic acid (36%) were rather low. The high prevalence of multiresistant bacteria in live feed contributes to enrich the resistant microbiota of reared fish larvae, thus proper management strategies appear to be highly necessary to prevent future antibacterial therapy failures. Study supported by grant 1171772 of CONICYT, Chile. [ABSTRACT FROM AUTHOR]

Intestinal microbiota has been involved in several processes that benefit the host, such as digestion, nutrient metabolism, resistance to pathogens colonization and immune function. In this study, we investigated the diversity, composition and functional prediction of microbiota of reared Seriolella violacea (palm ruff) in the same cohort sampled at different times (7-, 8- and 9-month-old). Microbial community structure analyses, using 16S rRNA amplicon sequencing, revealed that the intestinal microbiota was dominated by the phyla Firmicutes, Proteobacteria, Fusobacteria and Tenericutes. At the genus level, Candidatus Arthromitus was the most abundant in all sampled timepoints, representing in average 78% of the bacterial community (ranging from 18 to 98%), corresponding to segmented filamentous bacteria, which are interesting because they have been associated with the maturation of immune responses in the gut and protecting the host from bacterial infections. The comparisons of the intestinal microbiota among the three groups showed differences in abundance of bacterial taxa and also in alpha diversity indexes (Shannon and Simpson), as well as beta diversity metrics (weighted and unweighted UniFrac). Potential functions of the intestinal microbiota of palm ruff were retrieved using Philipin and Tax4fun and these analyses revealed high levels of genes for sugar metabolism. To our knowledge, this study represents the first description of the intestinal microbiota of S. violacea. [ABSTRACT FROM AUTHOR]

The interest in and demand for natural dyes has increased significantly in recent years; however, very few natural blue dyes are commercially available, because blue colored compounds in nature are relatively rare. In this study, a blue pigment-producing bacteria from Lake Chungará (Atacama Desert, Chile) was isolated, and its blue pigment was purified and chemically characterized. The pigment-producing strain was identified as Pseudarthrobacter sp. by 16S rRNA gene sequencing. The pigment was separated from the filtered culture medium by column chromatography/solid-phase extraction using different resins (ionic exchange, C-18, size exclusion). The strain produced up to 2.5 g L−1 of blue pigment, which was very soluble in water, partially soluble in methanol and insoluble in other organic solvents. The pigment was analyzed and characterized by analytical HPLC, UV-Vis, FT-IR, and H-NMR, and purified by semi-preparative HPLC. The pigment was non-toxic to brine shrimp (LD50 > 2.3 g L−1) and was stable at pH 6-10 at temperatures below 60 °C. HPLC analysis shows that the pigment is composed of four major blue fractions. The physicochemical properties and structural analysis demonstrate that this pigment belongs to the indochrome isomers, whose properties have yet to have been characterized. The high solubility in water, good stability in neutral and basic pH, and negligible toxicity of the blue pigment make it a good candidate suitable for several industrial and possibly some food applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Our results demonstrated the global spread of the emergent pathogen V. europaeus. • V. europaeus was isolated in Spain, France, and now for first time in Chile and US. • Genome of V. europaeus has been fully resolved for first time. • We also showed that the V. europaeus host range includes A. purpuratus. • This species affected the most important species reared in bivalve hatcheries. Vibrio europaeus is an emergent pathogen affecting the most important bivalve species reared in Spanish and French hatcheries. Using a genomic approach, we identified V. europaeus outside Europe for the first time from massive larval mortalities of scallop (Argopecten purpuratus) in Chile and from seawater near a shellfish hatchery in the US West Coast. Results show the worldwide spreading and potential impact of V. europaeus for aquaculture; these four countries are among the 10 major producers of mollusks. Pathogenicity of V. europaeus was demonstrated for the first time towards scallop, the second most important species for Chilean mariculture. [ABSTRACT FROM AUTHOR]