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Biofouling 2023is 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...
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 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 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 , and . 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 infections.
Topics: Animals; Quorum Sensing; Biofilms; Aeromonas hydrophila; Anti-Bacterial Agents
PubMed: 37968931
DOI: 10.1080/08927014.2023.2279998 -
Virulence Dec 2023Active flavins derived from riboflavin (vitamin B) are essential for life. Bacteria biosynthesize riboflavin or scavenge it through uptake systems, and both mechanisms...
Active flavins derived from riboflavin (vitamin B) are essential for life. Bacteria biosynthesize riboflavin or scavenge it through uptake systems, and both mechanisms may be present. Because of riboflavin's critical importance, the redundancy of riboflavin biosynthetic pathway (RBP) genes might be present. , the aetiological agent of furunculosis, is a pathogen of freshwater and marine fish, and its riboflavin pathways have not been studied. This study characterized the riboflavin provision pathways. Homology search and transcriptional orchestration analysis showed that has a main riboflavin biosynthetic operon that includes , , , and genes. Outside the main operon, putative duplicated genes , and , and a riboflavin importer encoding gene, were found. Monocistronic mRNA , and encode for their corresponding functional riboflavin biosynthetic enzyme. While the product of conserved the RibB function, it lacked the RibA function. Likewise, encodes a functional riboflavin importer. Transcriptomics analysis indicated that external riboflavin affected the expression of a relatively small number of genes, including a few involved in iron metabolism. was downregulated in response to external riboflavin, suggesting negative feedback. Deletion of , and showed that these genes are required for riboflavin biosynthesis and virulence in Atlantic lumpfish (). riboflavin auxotrophic attenuated mutants conferred low protection to lumpfish against virulent . Overall, has multiple riboflavin endowment forms, and duplicated riboflavin provision genes are critical for infection.
Topics: Animals; Aeromonas salmonicida; Gene Duplication; Virulence; Riboflavin; Fishes; Fish Diseases
PubMed: 36895132
DOI: 10.1080/21505594.2023.2187025 -
Water Research May 2024Free-living (FL) and particulate-associated (PA) communities are distinct bacterioplankton lifestyles with different mobility and dissemination routes. Understanding...
Free-living (FL) and particulate-associated (PA) communities are distinct bacterioplankton lifestyles with different mobility and dissemination routes. Understanding spatio-temporal dynamics of PA and FL fractions will allow improvement to wastewater treatment processes including pathogen and AMR bacteria removal. In this study, PA, FL and sediment community composition and antimicrobial resistance gene (ARG; tetW, ermB, sul1, intI1) dynamics were investigated in a full-scale municipal wastewater free-water surface polishing constructed wetland. Taxonomic composition of PA and FL microbial communities shifted towards less diverse communities (Shannon, Chao1) at the CW effluent but retained a distinct fraction-specific composition. Wastewater treatment plant derived PA communities introduced the bulk of AMR load (70 %) into the CW. However, the FL fraction was responsible for exporting over 60 % of the effluent AMR load given its high mobility and the effective immobilization (1-3 log removal) of PA communities. Strong correlations (r>0.8, p < 0.05) were observed between the FL fraction, tetW and emrB dynamics, and amplicon sequence variants (ASVs) of potentially pathogenic taxa, including Bacteroides, Enterobacteriaceae, Aeromonadaceae, and Lachnospiraceae. This study reveals niche differentiation of microbial communities and associated AMR in CWs and shows that free-living bacteria are a primary escape route of pathogenic and ARG load from CWs under low-flow hydraulic conditions.
Topics: Wetlands; Anti-Bacterial Agents; Drug Resistance, Bacterial; Wastewater; Bacteria; Microbiota; Waste Disposal, Fluid
PubMed: 38442607
DOI: 10.1016/j.watres.2024.121408 -
Fish & Shellfish Immunology Nov 2023The Macrobrachium rosenbergii industry is threatened by various Aeromonas, resulting in high mortality of adult prawns. However, there are few studies on the immune...
The Macrobrachium rosenbergii industry is threatened by various Aeromonas, resulting in high mortality of adult prawns. However, there are few studies on the immune response of M. rosenbergii infected with Aeromonas dhakensis. In this study, we observed the hepatopancreas and gills histopathologically, performed a comparative transcriptome analysis of the hepatopancreas, and analyzed the candidate gene expression of immune-related genes in the hemolymph, hepatopancreas, and gills of M. rosenbergii that had been infected with A. dhakensis. Histopathology revealed the hepatopancreas was successively inflamed, followed by cellular vacuolation, lumen deformation, and finally tissue erosion; partial and severe inflammation of the gills occurred successively, and eventually the gill tissue atrophy and the gill filaments detached from the gill arch. Transcriptome analysis showed that a total of 77,742 unigenes and 8664 differentially expressed genes (DEGs), and the immune-related DEGs were mainly enriched in lysosome and phagosome pathways. In addition, 4 immune-related candidate genes (RhoA, CASP9, PKC, and DSCIGN) based on KEGG and PPI analysis were monitored at 6, 12, and 24h post injection (hpi) in hepatopancreas, hemolymph and gills. Their spatio-temporal expression results indicated that A. dhakensis have activated the immune system of M. rosenbergii. The present study may provide new information on the complex immune mechanism of M. rosenbergii.
Topics: Animals; Palaemonidae; Gene Expression Profiling; Transcriptome; Aeromonas; Immunity
PubMed: 37838210
DOI: 10.1016/j.fsi.2023.109151 -
Aquatic Toxicology (Amsterdam,... Nov 2023Large yellow croaker (Larimichthys crocea) is an economically important fish in China, but its aquaculture industry has been threatened by both biotic and abiotic...
Large yellow croaker (Larimichthys crocea) is an economically important fish in China, but its aquaculture industry has been threatened by both biotic and abiotic stressors such as hypoxia and pathogens. In the current study, hsp20 genes were identified and analyzed systematically for the first time from the genome of large yellow croaker, and their roles in hypoxia response and Aeromonas hydrophila, Pseudomonas plecoglossicida infection were investigated. Herein, 11 hsp20 genes were identified and annotated, phylogenetic analysis and selection pressure analysis showed that the hsp20 genes were evolutionarily-constrained and their function was conserved among fishes. Besides, we observed the expression patterns of the hsp20 genes under hypoxia and two pathogens' stress. In brief, seven, four, seven genes responded to hypoxia stress, A. hydrophila infection and P. plecoglossicida challenge, respectively, which indicated that they were involved in hypoxia and disease responses. Furthermore, pathogen- and time-specific pattern was observed after A. hydrophila and P. plecoglossicida infection whereas tissue-specific pattern was observed after hypoxia exposure, revealing that hsp20 genes showed differential functions in response to hypoxia and immune stress. Taken together, these results provided preliminary information for future analysis of the roles of hsp20 genes in both biotic and abiotic stress response in fish.
Topics: Animals; Phylogeny; Water Pollutants, Chemical; Perciformes; Aeromonas hydrophila; Hypoxia; Fish Proteins; Fish Diseases
PubMed: 37837866
DOI: 10.1016/j.aquatox.2023.106700 -
Comparative Biochemistry and... Jun 2024With the development of large-scale intensive feeding, growth performance and animal welfare have attracted more and more attention. Exogenous probiotics can promote the...
With the development of large-scale intensive feeding, growth performance and animal welfare have attracted more and more attention. Exogenous probiotics can promote the growth performance of fish through improving intestinal microbiota; however, it remains unclear whether intestinal microbiota influence physiological biomarkers. Therefore, we performed metagenomic and metabolomic analysis to investigate the effects of a 90-day Lactiplantibacillus plantarum supplementation to a basal diet (1.0 × 10 CFU/g) on the growth performance, intestinal microbiota and their metabolites, and physiological biomarkers in Coilia nasus larvae. The results showed that the probiotic supplementation could significantly increase weight and body length. Moreover, it could also enhance digestive enzymes and tight junctions, and inhibit oxidative stress and inflammation. The metagenomic analysis showed that L. plantarum supplementation could significantly decrease the relative abundance of Proteobacteria and increase the relative abundance of Firmicutes. Additionally, pathogenic bacteria (Aeromonadaceae, Aeromonas, and Enterobacterales) were inhibited and beneficial bacteria (Bacillales) were promoted. The metabolome analysis showed that acetic acid and propanoic acid were significantly elevated, and were associated with Kitasatospora, Seonamhaeicola, and Thauera. A correlation analysis demonstrated that the digestive enzymes, tight junction, oxidative stress, and inflammation effects were significantly associated with the increased acetic acid and propanoic acid levels. These results indicated that L. plantarum supplementation could improve intestinal microbial community structure and function, which could raise acetic acid and propanoic acid levels to protect intestinal health and improve growth performance in C. nasus larvae.
Topics: Animals; Probiotics; Metabolome; Gastrointestinal Microbiome; Larva; Metagenome; Fishes; Intestines
PubMed: 38643745
DOI: 10.1016/j.cbd.2024.101230 -
FEMS Microbiology Ecology Nov 2023Aeromonas hydrophila is a major pathogenic species that causes mass mortality in various freshwater fish species including hybrid tilapia, the main fish species in...
Aeromonas hydrophila is a major pathogenic species that causes mass mortality in various freshwater fish species including hybrid tilapia, the main fish species in Israeli aquaculture. Our hypothesis was that A. hydrophila infection may cause changes in the microbiota composition of fish internal organs, and therefore we aimed to study the effect of A. hydrophila infection by injection or by net handling on the microbiota compositions of fish intestine, spleen, and liver. Significant differences in the microbiota composition were found between the internal organs of the diseased and the healthy fish in both experimental setups. Fusobacteriota was the most dominant phylum in the microbiota of healthy fish (∼70%, liver). Cetobacterium was the most abundant genus and relatively more abundant in healthy, compared to diseased fish. When A. hydrophila was inoculated by injection, it was the only pathogenic genus in the spleen and liver of the diseased fish. However, in the handling experiment, Vibrio was also detected in the diseased fish, demonstrating coinfection interactions. Based on these experiments, we conclude that indeed, A. hydrophila infection in tilapia causes changes in the microbiota composition of fish internal organs, and that fish net handling may trigger bacterial infection in freshwater aquaculture.
Topics: Animals; Tilapia; Fish Diseases; Microbiota; Gram-Negative Bacterial Infections; Aeromonas hydrophila
PubMed: 37881004
DOI: 10.1093/femsec/fiad137 -
PloS One 2024This study aimed to investigate AMR profiles of Aeromonas hydrophila, Salmonella spp., and Vibrio cholerae isolated from Nile tilapia (Oreochromis spp.) (n = 276)...
This study aimed to investigate AMR profiles of Aeromonas hydrophila, Salmonella spp., and Vibrio cholerae isolated from Nile tilapia (Oreochromis spp.) (n = 276) purchased from fresh markets and supermarkets in Bangkok, Thailand. A sample of tilapia was divided into three parts: fish intestine (n = 276), fish meat (n = 276), and liver and kidney (n = 276). The occurrence of A. hydrophila, Salmonella, and V. cholerae was 3.1%, 7.4%, and 8.5%, respectively. A high prevalence of these pathogenic bacteria was observed in fresh market tilapia compared to those from supermarkets (p < 0.05). The predominant Salmonella serovars were Paratyphi B (6.4%), followed by Escanaba (5.7%), and Saintpaul (5.7%). All isolates tested positive for the virulence genes of A. hydrophila (aero and hly), Salmonella (invA), and V. cholerae (hlyA). A. hydrophila (65.4%), Salmonella (31.2%), and V. cholerae (2.9%) showed multidrug resistant isolates. All A. hydrophila isolates (n = 26) exhibited resistant to ampicillin (100.0%) and florfenicol (100.0%), and often carried sul1 (53.8%) and tetA (50.0%). Salmonella isolates were primarily resistant to ampicillin (36.9%), with a high incidence of blaTEM (26.2%) and qnrS (25.5%). For V. cholerae isolates, resistance was observed against ampicillin (48.6%), and they commonly carried qnrS (24.3%) and tetA (22.9%). To identify mutations in the quinolone resistance determining regions (QRDRs), a single C248A point mutation of C248A (Ser-83-Tyr) in the gyrA region was identified in six out of seven isolates of Salmonella isolates. This study highlighted the presence of antimicrobial-resistant pathogenic bacteria in Nile tilapia at a selling point. It is important to rigorously implement strategies for AMR control and prevention.
Topics: Animals; Anti-Bacterial Agents; Cichlids; Drug Resistance, Bacterial; Thailand; Ampicillin; Aeromonas hydrophila; Salmonella; Foodborne Diseases
PubMed: 38564611
DOI: 10.1371/journal.pone.0299987 -
Food Research International (Ottawa,... Jan 2024Biofilm formation by Aeromonas hydrophila in the food industry poses significant challenges to food safety and quality. Therefore, this comprehensive review aimed to... (Review)
Review
Biofilm formation by Aeromonas hydrophila in the food industry poses significant challenges to food safety and quality. Therefore, this comprehensive review aimed to provide insights into the mechanisms and key factors influencing A. hydrophila biofilm formation. It explores the molecular processes involved in initial attachment, microcolony formation, and biofilm maturation; moreover, it concurrently examines the impact of intrinsic factors, including quorum sensing, cyclic-di-GMP, the efflux pump, and antibiotic resistance, as well as environmental conditions, such as temperature, nutrient availability, and osmotic pressure, on biofilm architecture and resilience. Furthermore, the article highlights the potential of bibliometric analysis as a promising method for conceptualizing the research landscape of and identifying knowledge gaps in A. hydrophila biofilm research. The findings underscore the requirement for focused interventions that prevent biofilm development and raise food sector safety. The consolidation of current information and incorporation of bibliometric analysis enhances existing understanding of A. hydrophila biofilm formation and offers insights for future research and control strategies within a food industry context.
Topics: Aeromonas hydrophila; Biofilms; Quorum Sensing; Bibliometrics; Food Industry
PubMed: 38129021
DOI: 10.1016/j.foodres.2023.113671 -
Fish & Shellfish Immunology Sep 2023C-type lectins, one of the pattern recognition receptors (PRRs), play significant roles in innate immune responses through binding to the pathogen-associated molecular...
C-type lectins, one of the pattern recognition receptors (PRRs), play significant roles in innate immune responses through binding to the pathogen-associated molecular patterns (PAMPs) presented on surfaces of microorganisms. Here, a novel C-type lectin (named as MaCTL) from blunt snout bream (Megalobrama amblycephala) was cloned and characterized. The open reading frame (ORF) of MaCTL is 573 bp long encoding a putative protein of 190 amino acids (aa), which contains a typical feature of signal peptide at 1-23 aa, a characteristic CRD domain at 45-178 aa and a WND/EPN motif that is required for carbohydrates-binding specificity. Phylogenetic analysis indicated that MaCTL is a novel member of CTL family and possessed the highest similarity to that of grass carp (92.11%). The qRT-PCR analysis revealed that MaCTL expressed widely in all examined normal tissues, including heart, liver, spleen, kidney, head-kidney, gill, intestine and muscle, with the higher expression in the spleen, liver and muscle. The expression of MaCTL in spleen was significantly elevated, peaking at 9 h and 6 h after LPS stimulation and Aeromonas hydrophila challenge, respectively, suggesting its association with involvement in innate immune response. The recombinant MaCTL protein (rMaCTL) agglutinated markedly both Gram-positive (Staphylococcus aureus) and Gram-negative bacteria, including Escherichia coli, Vibrio anguillarum, Vibrio vulnificus and Aeromonas hydrophila, in a Ca-dependent manner. Meanwhile, rMaCTL showed the binding effects on the five bacteria and four carbohydrates, such as glucose, surose, LPS and PGN. Moreover, rMaCTL could remarkably inhibit the growth of three types of bacteria in vitro. Overall, the results obtained above demonstrated firmly that MaCTL binds to carbohydrates on the surface of diverse pathogens as a PRR and elicits antimicrobial responses, which shed new light on a better understanding of antibacterial functions of CTLs in teleost fish.
Topics: Animals; Lectins, C-Type; Cyprinidae; Phylogeny; Lipopolysaccharides; Amino Acid Sequence; Fish Proteins; Base Sequence; Immunity, Innate; Cypriniformes; Recombinant Proteins; Aeromonas hydrophila
PubMed: 37482206
DOI: 10.1016/j.fsi.2023.108966