Infectious Diseases In Fish Research Articles

The characterization of BCL-xL displays a non-apoptotic role in suppression of NLRP1 inflammasome assembly in common carp (Cyprinus carpio L.)

The NLRP1 inflammasome is a crucial muti-protein complex in the host anti-pathogen immune response. The previous studies have revealed that the anti-apoptotic protein BCL-xL played a non-apoptotic role by impeding the activation of NLRP1 inflammasome in mammals. However, the potential role of BCL-xL in regulating the inflammasome in fish remains unclear. In the present study, the BCL-xL (CcBCL-xL) was cloned from the head kidney of common carp (Cyprinus carpio L.), and its regulatory effect on the NLRP1 inflammasome was explored. It was found that CcBCL-xL predominantly localized in the brain, spleen and head kidney of common carp, and upon stimulation with Aeromonas hydrophila (A. hydrophila), Edwardsiella tarda (E. tarda), or spring viremia of carp virus (SVCV), the expression of CcBCL-xL significantly increased in multiple immune organs. The interaction between CcBCL-xL and CcNLRP1 was confirmed by co-immunoprecipitation and immunofluorescence. Meanwhile, we also found that CcBCL-xL significantly inhibited the assembly of the CcNLRP1 inflammasome, through ASC oligomerization, ASC specks formation and cytotoxicity experiments. Furthermore, our results revealed that CcBCL-xL interacted with the NACHT, LRR, FIIND, and CARD domains of CcNLRP1. Taken together, the results provide a theoretical foundation for further exploring the regulatory mechanism of NLRP1, and for the prevention and treatment of infectious diseases in fish.

The application of plasmid DNA constructs encoding antiviral proteins as potential therapeutics against viral infections in salmonid aquaculture

Treatments to control infectious diseases in aquacultured fish commonly focus on the use of antibiotics (which are ineffective against viruses) and inorganic disinfectants. Currently, antiviral treatments are not available for use in aquaculture. The use of plasmid vectors to overexpress antiviral proteins in fish has been reported, with positive results against viral infections. The aim of this work was to overexpress the antiviral proteins interferon-induced protein with tetratricopeptide repeats 5 (IFIT5) and natural killer enhancing factor (NKEF) using plasmid vectors (pIFIT5 and pNKEF) as novel therapeutic agents against viral infections. The antiviral activity of pIFIT5 against viral hemorrhagic septicemia virus (VHSV) and infectious pancreatic necrosis virus (IPNV) was evaluated in vitro in epithelioma papulosum cyprinid and Chinook salmon embryo cell lines. Moreover, pNKEF antiviral activity against IPNV was also evaluated. Results showed that pIFIT5 had antiviral activity against both viruses, but pNKEF did not protect against IPNV. In addition, we evaluated the use of pIFIT5 and pNKEF constructs as therapeutics in rainbow trout. Biodistribution assays demonstrated systemic distribution of the IFIT5-TFP1 and NKEF-TFP1 proteins in rainbow trout injected with the plasmids, and pIFIT5 and pNKEF triggered an immune response in the injected fish. In a pilot study, we evaluated the level of protection conferred by pIFIT5 and pNKEF against VHSV in rainbow trout, and we observed 10 % survival for pIFIT5 compared to pTFP. Together, these results suggest the potential of pIFIT5 as therapeutic agent in aquaculture.

Fish Welfare – A Case Study: Reviling for the first-time side effects of vaccination in European sea bass (Dicentrarchus labrax) and barramundi (Lates calcarifer) in the Israeli fish farming

Vaccination is an effective way to control many infectious diseases in fish. Israeli fish farming has successfully used two vaccines over the last 30 years and has no problem with the side effects of vaccination. However, after introducing new species, a new problem emerged: these fish, after vaccination, demonstrated peritoneal lesions such as granulomas. At the same time, the fish did not show retarded growth or suffering during the fattening period. This study was conducted to establish the connection between vaccination and the appearance of granulomas. Evidence drawn from this research work and comparing vaccinated and non-vaccinated fish confirms that intraperitoneal granulomas do not impact the growth, performance, or fish fillet quality at harvest.

Computational design of novel chimeric multiepitope vaccine against bacterial and viral disease in tilapia (Oreochromis sp.)

Regarding several infectious diseases in fish, multiple vaccinations are not favorable. The chimeric multiepitope vaccine (CMEV) harboring several antigens for multi-disease prevention would enhance vaccine efficiency in terms of multiple disease prevention. Herein, the immunogens of tilapia’s seven pathogens including E. tarda, F. columnare, F. noatunensis, S. iniae, S. agalactiae, A. hydrophila, and TiLV were used for CMEV design. After shuffling and annotating the B-cell epitopes, 5,040 CMEV primary protein structures were obtained. Secondary and tertiary protein structures were predicted by AlphaFold2 creating 25,200 CMEV. Proper amino acid alignment in the secondary structures was achieved by the Ramachandran plot. In silico determination of physiochemical and other properties including allergenicity, antigenicity, glycosylation, and conformational B-cell epitopes were determined. The selected CMEV (OSLM0467, OSLM2629, and OSLM4294) showed a predicted molecular weight (MW) of 70 kDa, with feasible sites of N- and O-glycosylation, and a number of potentially conformational B-cell epitope residues. Molecular docking, codon optimization, and in-silico cloning were tested to evaluate the possibility of protein expression. Those CMEVs will further elucidate in vitro and in vivo to evaluate the efficacy and specific immune response. This research will highlight the new era of vaccines designed based on in silico structural vaccine design.

A novel cell line established from skin tissue of gibel carp (Carassius gibelio) is susceptible to Carassius auratus herpesvirus infection

Frequent outbreaks of emerging infectious diseases in fish, such as Carassius auratus herpesvirus (CaHV) infection has caused great economic losses in China. However, the lack of a sensitive cell culture system has limited studies of CaHV. In the present study, a new cell line (gibel carp skin cell, GiCS) derived from gibel carp (Carassius gibelio) skin tissue was established to create a valuable tool for research of the virus. The GiCS cells consisted mainly of epithelial-like cells, which grew well at 25 ​°C in L-15 medium supplemented with 10–20% fetal bovine serum. Chromosomal analysis revealed that the skin cell line remained amphitriploid, with most chromosome counts being 156 (54%). The GiCS cells can be efficiently transfected and expressed exogenous genes. In particular, the GiCS cells showed high susceptibility to CaHV infection, which was confirmed by virus infection tests, detection of viral gene expression, and ultrastructural observation. To our knowledge, it is the first cell line that is highly permissive to CaHV infection. In addition, the cells also showed susceptibility to several aquatic animal viruses from different families including Iridoviridae, Rhabdoviridae, and Reoviridae. In conclusion, these results indicated that the establishment of the GiCS cell line is a significant advance that will be beneficial to future studies of CaHV and other aquatic animal viruses.

Determination of Raman spectrum under different culture conditions: preliminary research on bacterial fish pathogens

The intensive labour and time required for conventional methods to identify bacterial fish pathogens have revealed the need to develop alternative methods. Raman spectroscopy has been used in the rapid optical identification of bacterial pathogens in recent years as an alternative method in microbiology. Strains of bacterial fish pathogens (Vibrio anguillarum, Lactococcus garvieae and Yersinia ruckeri) that often cause infectious diseases in fish were here identified and analyzed in terms of their biochemical structures in different media and at different incubation times, and the data were specified by using Raman spectroscopy. The results demonstrated that Raman spectroscopy presents species-specific Raman spectra of each disease-causing bacteria and that it would be more appropriate to choose general microbiological media over selective media for routine studies. Additionally, it was found that species-specific band regions did not differ in 24- and 48-hour cultures, but there could be a difference in peak intensity which may lead to difficult characterization of spectrum. The current study, conducted for the first time with bacterial fish pathogens under different incubation conditions, is believed to provide a basis for the routine use of Raman spectroscopy for quick pathogen identification and the precise determination of the methodology for further research.

JunD functions as a transcription factor of IL-10 to regulate bacterial infectious inflammation in grass carp (Ctenopharyngodon idella)

IL-10 is a key anti-inflammatory mediator ensuring the protection of a host from excessive inflammation in response to pathogen infections, whose transcription or expression levels are tightly linked to the onset and progression of infectious diseases. An AP-1 family member called CiJunD was shown to be a transcription factor of IL-10 in grass carp (Ctenopharyngodon idella) in the current study. CiJunD protein harbored the conserved Jun and bZIP domains. Mutant experiments demonstrated that CiJunD bound to three specific sites on IL-10 promoter, i.e., 5′-ATTATTCATA-3′, 5′-AGATGAGACATCT-3′, and 5′-ATTATTCATC-3′, mainly relying on the bZIP domain, and initiated IL-10 transcription. Expression data from the grass carp spleen infected by Aeromonas hydrophila and lipopolysaccharide (LPS) challenged spleen leukocytes indicated that the expressions of CiJunD and IL-10 were positively correlated, while the expression of pro-inflammatory cytokines, such as IL-1β, IL-6, IL-8, IFN-γ, and TNF-α, showed an overall downward trend when CiJunD and IL-10 peaked. The ability of CiJunD to down-regulate the production of pro-inflammatory cytokines and up-regulate the expression of IL-10, both with and without LPS stimulation, was confirmed by overexpression experiments. Meanwhile, the subcellular fractionation assay revealed that the nuclear translocation of CiJunD was significantly enhanced after the LPS challenge. Moreover, in vivo administration of grass carp with Oxamflatin, a potent agonist of JunD activity, could promote IL-10 but suppress the expression of pro-inflammatory cytokines. Intriguingly, tissue inflammation lesions and the survival rates of grass carp infected with A. hydrophila were also significantly improved by Oxamflatin administration. This work sheds light on the regulation mechanism by JunD of IL-10 expression and bacterial infectious inflammation for the first time, and it may present a viable method for preventing infectious diseases in fish by regulating IL-10 expression and inflammatory response.

Transcriptome analysis reveals the relationship between Spring viremia of carp N protein-induced endoplasmic reticulum stress in Epithelioma papulosum cyprinid (EPC) cells and apoptosis and autophagy

Spring viremia of carp virus(SVCV) is one of the important pathogens of viral infectious diseases in fish, which brings severe economic losses to the aquaculture industry and is familiar and challenging to control viral disease in aquaculture. Currently, studies have shown that SVCV can induce endoplasmic reticulum stress, whereas the relationship between whether the most abundant protein of SVCV-N, can induce endoplasmic reticulum stress, autophagy and apoptosis has not been reported. In this study, the SVCV-N protein was overexpressed in EPC cells. According to transcriptome analysis of gene changes in EPC cells, there were 2290 differentially expressed genes, 1137 up-regulated and 1153 down-regulated genes compared to controls transfected with the empty vector pCS 2 + 8CmCherry. After gene ontology (GO) analysis, they were classified into three categories: biological processes, molecular functions and cellular components. KEGG enrichment analysis showed that 722 differentially expressed genes were enriched in 190 KEGG pathways, most of them were enriched in endoplasmic reticulum processing. Western blotting showed that GRP78, Beclin1 and Lc3-II/Lc3- I protein expression was increased, and p62 protein expression was decreased. Flow cytometry showed an increased rate of apoptosis. Activation inhibition experiments showed that activation of endoplasmic reticulum stress expression by SVCV-N protein promotes autophagy and apoptosis, and vice versa. The qRT-PCR results are consistent with the RNA-Seq, indicating that the transcriptome sequencing data are reliable. This study provides preliminary insight into the pathogenic mechanism of SVCV-N infection and provides data to reveal the mechanism.

Overview on the Biosecurity Measures of Salmonid Fish Farms: A Case Study in Italy

Italy is one of the main European producers of trout fish, and the most important producing area is the Autonomous Province of Trento (APT) in the North East. The objective of the study was to obtain a snapshot of the trout farms of the APT by identifying biosecurity factors, objectifying them, and classifying the establishments accordingly. Data from 62 salmonid farms were collected using a national checklist in which biosecurity elements were identified and assessed using the method of expert elicitation. The purpose was to evaluate the levels of biosecurity of a trout farm in order to rank the risk of introduction and spread of infectious fish diseases. The main critical factors identified during this study were as following: (i) cleaning and disinfection of the cargo truck; (ii) regular collection, storage, and disposal of dead fish; (iii) presence of anti-bird nets; (iv) use of dedicated equipment for the different sectors of the farm; and (v) presence of external areas dedicated to the loading of dead fish.

Neem oil against Aeromonas hydrophila infection by disrupting quorum sensing and biofilm formation

Aeromonas hydrophila is an opportunistic pathogen that can cause a number of infectious diseases in fish and is widely distributed in aquatic environments. Antibiotics are the main approach against A. hydrophila infections, while the emergence of resistant bacteria limits the application of antibiotics. Here, quorum-sensing (QS) was defined as the target and the inhibitory effects of neem oil against QS of A. hydrophila was studied. The results showed that neem oil could dose-dependently reduce aerolysin, protease, lipase, acyl-homoserine lactones (AHLs), biofilm and swarming motility at sub-inhibitory concentrations. Results of real-time PCR demonstrated that neem oil could down-regulate the transcription of aerA, ahyI and ahyR. Moreover, neem oil showed significant protections to A549 cells and a fish infection model. Taken together, these results indicated that neem oil could be chosen as a promising candidate for the treatment of A. hydrophila infections.

Synthesis and Characterization of Mithun (Bos frontalis) Urine-Based Antibacterial Copper Oxide Nanoparticles.

The increased prevalence of disease, mortality, and antibiotic resistance among aquatic microorganisms has renewed interest in non-conventional disease prevention and control approaches. Nanoparticles present several benefits in aquaculture and hold significant potential for controlling both human and animal infections. This study reports on the antibacterial properties of green copper oxide nanoparticles (CuO NPs) synthesized from the urine of Mithun (MU) (Bos frontalis). In addition, an array of analytical techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-visible spectroscopy (UV), and Fourier transform infrared spectroscopy (FTIR), were employed to investigate the synthesized MU-CuO nanoparticles. Aeromonas hydrophila and Aeromonas veronii, two bacterial fish pathogens known to cause severe infectious diseases in fish, were tested for their antibacterial efficacy against MU-CuO NPs. At 100 µg/mL, MU-CuO NPs exhibit enhanced antibacterial efficacy against two bacterial pathogens commonly found in fish. Applications in aquaculture may be looked at given that MU-CuO NPs showed greater antibacterial activity.

Phenotypic and genotypic comparison of pathogenic group B Streptococcus isolated from human and cultured tilapia (Oreochromis species) in Malaysia

Group B Streptococcus (GBS) is a major cause of several infectious diseases in humans and fish. This study was conducted to compare human and fish-derived GBS in terms of their antimicrobial susceptibility, serotype, virulence and pili genes and sequence type (ST), and to determine whether there is a potential linkage of zoonotic transmission in Malaysia. GBS isolated from humans and fish had similar phenotypic characteristics and differed in virulence gene profile, antimicrobial susceptibility, serotype and sequence type. Fish GBS isolates had lower genetic diversity and higher antibiotic susceptibility than human isolates. We report a rare detection of the potentially fish-adapted ST283 in human GBS isolates. Both human and fish ST283 shared several phenotypic and genotypic features, including virulence and pilus genes and antimicrobial susceptibility, illustrating the value of monitoring GBS within the One Health scope. In this study, two human GBS ST283 isolates belonging to the variant common in fish hosts were identified, raising awareness of the zoonotic potential between the different species in Malaysia.

Investigation of the Genus Flavobacterium as a Reservoir for Fish-Pathogenic Bacterial Species: the Case of Flavobacterium collinsii.

Bacteria of the genus Flavobacterium are recovered from a large variety of environments. Among the described species, Flavobacterium psychrophilum and Flavobacterium columnare cause considerable losses in fish farms. Alongside these well-known fish-pathogenic species, isolates belonging to the same genus recovered from diseased or apparently healthy wild, feral, and farmed fish have been suspected to be pathogenic. Here, we report the identification and genomic characterization of a Flavobacterium collinsii isolate (TRV642) retrieved from rainbow trout spleen. A phylogenetic tree of the genus built by aligning the core genome of 195 Flavobacterium species revealed that F. collinsii stands within a cluster of species associated with diseased fish, the closest one being F. tructae, which was recently confirmed as pathogenic. We evaluated the pathogenicity of F. collinsii TRV642 as well as of Flavobacterium bernardetii F-372T, another recently described species reported as a possible emerging pathogen. Following intramuscular injection challenges in rainbow trout, no clinical signs or mortalities were observed with F. bernardetii. F. collinsii showed very low virulence but was isolated from the internal organs of survivors, indicating that the bacterium is able to survive inside the host and may provoke disease in fish under compromised conditions such as stress and/or wounds. Our results suggest that members of a phylogenetic cluster of fish-associated Flavobacterium species may be opportunistic fish pathogens causing disease under specific circumstances. IMPORTANCE Aquaculture has expanded significantly worldwide in the last decades and accounts for half of human fish consumption. However, infectious fish diseases are a major bottleneck for its sustainable development, and an increasing number of bacterial species from diseased fish raise a great concern. The current study revealed phylogenetic associations with ecological niches among the Flavobacterium species. We also focused on Flavobacterium collinsii, which belongs to a group of putative pathogenic species. The genome contents revealed a versatile metabolic repertoire suggesting the use of diverse nutrient sources, a characteristic of saprophytic or commensal bacteria. In a rainbow trout experimental challenge, the bacterium survived inside the host, likely escaping clearance by the immune system but without provoking massive mortality, suggesting opportunistic pathogenic behavior. This study highlights the importance of experimentally evaluating the pathogenicity of the numerous bacterial species retrieved from diseased fish.

Effects of TLR2/4 signalling pathway in western mosquitofish (Gambusia affinis) after Edwardsiella tarda infection.

Gambusia affinis is regarded as an important animal model. Edwardsiella tarda is one of the most serious pathogens affecting aquaculture. The study explores the effects of TLR2/4 partial signalling pathway in G.affinis of E.tarda infection. The study collected the brain, liver, and intestine after E. tarda LD50 and 0.85% NaCl solution challenge at different times (0h, 3h, 9h, 18 h, 24 h, and 48 h). In these three tissues, the mRNA levels of PI3K, AKT3, IRAK4, TAK1, IKKβ, and IL-1β were substantially enhanced (p < .05) then returned to normal levels. Additionally, Rac1 and MyD88 in liver had different trend with other genes in brain and intestine, which displayed significantly indifference. The overexpression of IKKβ, and IL-1β indicated that E.tarda also caused immune reaction in intestine and liver, which would be consistent with delayed edwardsiellosis, which causes intestinal lesions and liver and kidney necrosis. Additionally, MyD88 plays a smaller role than IRAK4 and TAK1 in this signalling pathways. This study could enrich the understanding of the immune mechanism of the TLR2/4 signalling pathway in fish and might help to prescribe preventive measures against E.tarda to prevent infectious diseases in fish.

Микробиоценоз кишечника радужной форели в условиях садкового хозяйства

Abstract. The rapid growth of the aquaculture industry using modern intensive farming methods has led to a number of problems related to water quality and the spread of infectious diseases in fish. The intestinal physiological microbiota of fish and the surrounding aquatic environment forming an ecosystem, the balance of which is a key factor in maintaining the health of aquaculture. However, optimizing the microbiota is still a challenging task due to a lack of studies about the dominant microorganisms in aquacultures and the influence of environmental factors on it. The aim of this work was to study the structure and taxonomic composition of the cultivatable bacterial gut community of the rainbow trout Oncorhynchus mykiss under the conditions of the “Yaroslavskaya Trout” cage farm. Methods. To identify the isolated strains and characterize the composition of common bacterial communities were used phenotypic and biochemical characteristics, as well as amplification and sequencing of 16S rRNA gene fragments and subsequent phylogenetic analysis. Scientific novelty. Data on the taxonomic diversity of the cultivated rainbow trout gut microbiome have been obtained. A comparative analysis of fish intestinal microbiocenoses and the surrounding aquatic environment was carried out. Results and practical significance. Gammaproteobacteria was the most abundant bacteria in the structure of the studied microbial communities. Bacteria of the genera Pseudomonas, Stenotrophomonas, and Aeromonas were found in the microbiome of both the rainbow trout intestines and the surrounding aquatic environment, which are opportunistic pathogens and can lead to an outbreak of bacterial infections under stressful conditions. However, studies have shown that the surrounding aquatic microbiome does not always reflect the microbiome of aquatic organisms. A comparative analysis of the freshwater microbiomes and the gut microbiome of rainbow trout revealed the ability of the host organism to concentrate beneficial probiotic microorganisms even under conditions of pathogenic presure. The resulting collection of microorganisms can be further used for screening potential probiotic cultures.

Florfenicol and Florfenicol Amine Quantification in Bull Serum and Seminal Plasma by a Single Validated UHPLC-MS/MS Method.

Florfenicol is a broad-spectrum antibiotic belonging to the amphenicols class that inhibits protein synthesis by binding to bacteria's ribosomal subunits. This drug is commonly used in veterinary medicine to treat bacterial infectious diseases in cattle, swine, poultry, and fish. The proposed method uses a quick protein precipitation with acetonitrile for the extraction of florfenicol and florfenicol amine in serum and seminal plasma, followed by analysis in UHPLC-MS/MS for their simultaneous quantification. A BEH C18 reversed-phase column was chosen for analyte separation, allowing to obtaining sharp and symmetrical peak shapes in a chromatographic run of just 3.5 min under programmed conditions. Two specific transitions were observed for each analyte, and florfenicol-d3 was used as the internal standard. The approach was fully validated in each matrix over ranges suitable for field concentrations of florfenicol and florfenicol amine, showing good linearity during each day of testing (R2 always >0.99). Excellent accuracy and precision were demonstrated, for both analytes, by calculated bias always within ±15% and CV% always below 15% at all QC levels tested. The satisfactory outcomes obtained during recovery, matrix effect, and process efficiency investigations in serum and seminal plasma confirmed the strength of the method for the quantification of target compounds. To our knowledge, this is the first LC-MS/MS-validated approach for the quantification of florfenicol and florfenicol amine in serum and seminal plasma and was successfully applied for the determination of their concentration-time profiles in bulls. This paves the way to understanding the pharmacokinetics of this antibiotic and its active metabolite in bull's seminal plasma, which will enable the design of more appropriate treatment protocols.

ISOLATION AND CHARACTERIZATION OF BACTERIAL PATHOGENIC Bacillus sp. FROM THE Lethrinus lentjanin COASTAL AREA OF INDIA

India stands at the sixth-largest position in the sector of marine and freshwater fisheries and the second-largest in the production of aquaculture. In view of the economic benefits, this highlights the importance of controlling infectious fish diseases that pose threat to the production of aquaculture. It was hypothesized lesions found on the dorsal scales in the Lenthrinus lentjan, could be the reason for the massive morbidity and mortality. Live surface floating fish samples with pathological signs were collected from offshore areas of the Pallam fishing village, located in the Kanyakumari District of Tamil Nadu, India in August 2013. Detailed histological studies confirmed the presence of similar bacterial infections in the tissues adjacent to the lesion sites. The pathogen was isolated and it was subjected to a series of biochemical and 16S RNA sequencing and it was identified the causative bacterial pathogen as Bacillus sp. The pathogen possessed sub-terminal endospore-forming nature and also it has strong hemolytic activities. The organism was named as Bacillus sp. MSU1400. Furtherly, the study was complemented with the Pasteur method, performed on white carp fishes, in vitro, for the confirmation of the pathogen. The pathogen was sensitive to ampicillin, cephalexin, and gentamycin but it was resistant to tetracycline.

An overview of the antimicrobial activity of some essential oils against fish pathogenic bacteria

Plant-derived essential oils as an alternative treatment method for antimicrobial-resistant bacteria have gained interest over the past few decades, particularly in the food and aquaculture industry. Essential oil is considered as a natural, cost-effective compound with a minimum impact on the environment. Studies have suggested the use of essential oils in the treatment and/or prevention of infectious diseases in fish may be a cost-effective alternative to synthetic antimicrobials. In addition to that,hundreds of different chemical profiles have been identified in essential oils. Particularly, in the same essential oil. In contrast to the synthetic antimicrobials that have unique chemical compositions between every product belonging to the same drug, the same essential oil may not perform unique antimicrobial activity every time. Therefore, more studies and concluded data are required for the effective usage of essential oils as an alternative to antimicrobial agents. In this review, we have summarized the studies about the several active essential oils that are known and tested against fish pathogenic bacteria because of their antimicrobial properties

Antimicrobial Activity of Lactic Acid Bacteria (Lab) Isolated from Yoghurt and Fish against Pathogenic Bacteria Isolated from Fish in Ethiopia

Pathogenic bacteria are causative agent of infectious diseases in fish. Antimicrobials are widely applied in fish products for prevention of fish-borne diseases. The global concern of antimicrobial resistance of bacteria raises attentiveness of the different ways of using antimicrobial peptides (AMPs). The aim of the present study was to detect the antimicrobial activity of the AMPs from Lactic acid bacteria (LAB) against the growth of pathogenic bacteria isolated from fish in Ethiopia. Cell Free Supernatants (CFSs) from 4 strains of LAB consisting of lactobacillus paracasei sub.paracasei, lactobacillus casei LC2W, Pediococcus acidilactici and lactobacillus plantarum were tested against pathogenic bacteria of Aeromonas hydrophila, Aeromonas veronii, Edwardsiella tarda, Escherichia coli, Proteus mirabilis, Pseudomonas fluorescens and Shigella flexneri via using agar well diffusion assay. All tested CFSs revealed antimicrobial activity against the tested fish pathogenic isolates at different extents. CFSs of lactobacillus plantarum, Lb. casei LC2W and lactobacillus paracasei sub.paracasei showed strong antibacterial activity against Edwardsiella tarda (19 mm), Aeromonas hydrophila (18 mm) and Pseudomonas fluorescens (18 mm) respectively, with the well diffusion assay. The study shows the antimicrobial activity of the 4 strains of LAB CFSs against the bacterial fish pathogens and indicates the application opportunities as fish product bio preservative.

Оценка эпизоотического благополучия и ветеринарно-санитарной безопасности водных биологических ресурсов Прибайкалья

The anatomical and morphological features of the main species of the whitefish family have been studied. The color of the back of the omul varies from brown to green, the sides are silvery. Peled has a dark gray color with a metallic sheen, while the back of the fish is almost black. Monitoring for infectious diseases of fish showed only isolated cases of deviations. When conducting chemical and toxicological studies of fish, compliance with the requirements of sanitary standards in terms of safety indicators in all reservoirs of the region was noted.