Summary The gut microbiome of vertebrates plays an integral role in host health by stimulating development of the immune system, aiding in nutrient acquisition and outcompeting opportunistic pathogens. Development of next‐generation sequencing technologies allows researchers to survey complex communities of microorganisms within the microbiome at great depth with minimal costs, resulting in a surge of studies investigating bacterial diversity of fishes. Many of these studies have focused on the microbial structure of economically significant aquaculture species with the goal of manipulating the microbes to increase feed efficiency and decrease disease susceptibility. The unravelling of intricate host–microbe symbioses and identification of core microbiome functions is essential to our ability to use the benefits of a healthy microbiome to our advantage in fish culture, as well as gain deeper understanding of bacterial roles in vertebrate health. This review aims to summarize the available knowledge on fish gastrointestinal communities obtained from metagenomics, including biases from sample processing, factors influencing assemblage structure, intestinal microbiology of important aquaculture species and description of the teleostean core microbiome.
BackgroundThe microbiota plays an essential role in host health, particularly through competition with opportunistic pathogens. Changes in total bacterial load and microbiota structure can indicate early stages of disease, and information on the composition of bacterial communities is essential to understanding fish health. Although Red Snapper (Lutjanus campechanus) is an economically important species in recreational fisheries and a primary aquaculture candidate, no information is available on the microbial communities of this species. The aim of this study was to survey the microbiota of apparently healthy, wild-caught Red Snapper from the Gulf of Mexico. Sampled Red Snapper showed no physical signs of disease. Tissues that are either primary entry routes for pathogens (feces, gill) or essential to disease diagnosis (blood) were sampled. Bacteria were enumerated using culture-based techniques and characterized by pyrosequencing.ResultsAerobic counts of feces and gill samples were 107 and 104 CFU g-1, respectively. All individuals had positive blood cultures with counts up to 23 CFU g-1. Gammaproteobacteria dominated the microbiota of all sample types, including the genera Pseudoalteromonas and Photobacterium in feces and Pseudomonas in blood and gill. Gill samples were also dominated by Vibrio while blood samples had high abundances of Nevskia. High variability in microbiota composition was observed between individuals, with percent differences in community composition ranging from 6 to 76 % in feces, 10 to 58 % in gill, and 52 to 64 % in blood.ConclusionsThis study provides the first characterization of the microbiota of the economically significant Red Snapper via pyrosequencing. Its role in fish health highlights the importance of understanding microbiota composition for future work on disease prevention using microbial manipulation.
The skin-associated microbiota of fish competes against pathogens for space and nutrients, preventing colonization by harmful bacteria encountered during environmental transitions such as those faced during stock enhancement. Thus, alterations in bacterial community structure during release of cultured fish have important implications for health of these individuals. This study investigated microbiota structure during acclimation of juvenile hatchery-reared common snook Centropomus undecimalis to the wild by comparing skin-associated microflora among snook in captivity, after 48 h of acclimation at release sites, and from the wild. After two days of acclimation, the microbiota of hatchery-reared snook mirrored that observed on wild snook. Relative abundances of potential pathogens were higher in captive fish, whereas acclimated and wild fish harbored bacterial taxa influenced by geographical factors and water quality at release sites. Predicted microbiota function of acclimated and wild fish showed higher production of protective amino acids and antimicrobials, identifying a mechanism for microbial supplementation of the immune defense of these fish. The two-day transition to wild-type microbiota suggests a temporal scale of hours associated with bacterial succession indicating that the microbiota, whose structure is vital to fish health, aids in acclimation of fish to new environments during stock enhancement efforts.
The need for sustainable bacterial management approaches in aquaculture is crucial for advancement of the industry. Probiotics are a promising strategy as evidenced by benefits demonstrated in intensive larviculture of various marine fish species. In this study we investigate the effects of a mixed Bacillus species (B. licheniformis and B. amyloliquefaciens) probiotic on rearing of larval common snook (Centropomus undecimalis). Experimental treatments included (1) probiotics supplemented to the water and live feed, (2) probiotics supplemented to the water only, and (3) no probiotic controls. Data from two separate trials indicated up to 2.5 times higher survival with probiotic addition, as well as 20% higher survival 7 days following a transport event. These benefits were not explained by faster growth, measured water quality parameters, or innate immune enzyme activities. Microbiota analysis indicated the importance of system stabilization prior to larval stocking to improve rearing success and probiotic performance. ied Potential probiotic benefits include accelerated gastrointestinal tract development, enhanced immunity, inhibition of opportunistic bacteria, and improvements to water quality parameters. Results suggest this probiotic should be tested in other marine fish species in order to reduce larval rearing bottlenecks.
Abstract:The use of prebiotics in aquaculture aims at increasing the numbers of beneficial microbes in the gastrointestinal tract of fishes. However, the true effect of prebiotics exert on the fish microbiome is for the most part unknown. This study aimed at investigating the effects of the commercial prebiotic Previda® and the feed supplement saponin on Nile tilapia (Oreochromis niloticus L.). We used 454 pyrosequencing to characterize the gut microbiome of fish fed diets containing Previda®, saponin, a combination of both, and a control diet. After data normalization, 98,300 sequence reads were analyzed resulting in 331 unique operational taxonomic units (OTUs). Three phyla were present in all samples: Fusobacteria, Bacteroidetes, and Proteobacteria. Fusobacteria was the predominant phylum in all samples accounting for more than 80% of the OTUs. Within the Fusobacteria, the predominant genus was Cetobacterium with more than 76% of the sequences being ascribed to that species. Barnesiella was the second most common genus with more than 6% of the total sequences. Overall, there was not a significant difference in the composition of the gut microbiomes regardless of the diet. The overwhelming numbers of Cetobacterium sp. present in the gut of Nile tilapia could overshadow the effect of the treatments on other genera.
The Deepwater Horizon (DWH) blowout resulted in the deposition of toxic polycyclic aromatic hydrocarbons (PAHs), in the coastal sediments of the Gulf of Mexico. The immediate effects on an ecosystem from an oil spill are clearly recognizable, however the long-term chronic effects and recovery after a spill are still not well understood. Current methodologies for biomonitoring wild populations are invasive and mostly lethal. Here, two potential nonlethal biomonitoring tools for the assessment of PAH toxicity and induced biological alterations in the field, were identified using laboratoryvalidated methods. In this study, subadult southern flounder (Paralichthys lethostigma) were chronically exposed to DWH surrogate oiled sediments for 35 days; a subset of these exposed flounder were then provided a clean nonexposure period to ascertain the utility of selected biomarkers to monitor recovery post exposure. After chronic exposure, there was an increase in gene expression of cytochrome P450 1A but not glutathione S-transferase. There was also a notable imbalance of oxidants to antioxidants, measured as reduced glutathione, oxidized glutathione, and their ratio in the blood. Evidence of subsequent oxidative damage due to chronic exposure was found through lipid peroxidation and DNA damage assessments of liver, gill, and blood.
Almaco jack (Seriola rivoliana Valenciennes) is an excellent candidate for aquaculture due to its fast growth rate and high market value. While S. rivoliana have adapted well to captivity, survival at early life stages can be improved to increase profitability during production. A wide range of variables cause larval mortalities but high bacterial loads in rearing tanks are often correlated with these losses. The aim of this study was to investigate the effect of egg disinfection on bacterial load and hatch rate of S. rivoliana. Disinfectants tested included formalin (F100 and F200; 100 and 200 mg/L, respectively, for 60 min), hydrogen peroxide (HPO; 300 mg/L for 10 min) and peracetic acid/hydrogen peroxide (PAA/HPO; 15.7 mg/L/39.6 mg/L for 1 min). Concentrations and contact times were determined based on current use in marine aquaculture and preliminary trials. Eggs treated with HPO and F100 had significantly higher hatch rates than the untreated control group. All treatments significantly decreased total Vibrio counts compared to untreated eggs; however, total bacterial counts were only decreased following treatments with PAA/HPO and F200. To prevent egg mortality due to bacterial overgrowth, consideration should be given to the use of surface disinfection using HPO or F100. Future studies should investigate the use of peracetic‐based products at lower doses.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.