scholarly journals Live Feeds Used in the Larval Culture of Red Cusk Eel, Genypterus chilensis, Carry High Levels of Antimicrobial-Resistant Bacteria and Antibiotic-Resistance Genes (ARGs)

Animals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 505
Author(s):  
Luz Hurtado ◽  
Claudio D. Miranda ◽  
Rodrigo Rojas ◽  
Félix A. Godoy ◽  
Mark A. Añazco ◽  
...  
Keyword(s):  
Fish Larvae ◽  
Larval Growth ◽  
Survival Rates ◽  
Larval Survival ◽  
Resistant Bacteria ◽  
Rrna Gene ◽  
Live Feed ◽  
Multiresistant Bacteria ◽  
A Priority ◽  
Genypterus Chilensis

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.

The box-balance model: a new tool to assess fish larval survival, applied to field data on two small pelagic fish

2020 ◽  
Vol 650 ◽  
pp. 289-308 ◽  
Author(s):  
V Raya ◽  
J Salat ◽  
A Sabatés
Keyword(s):  
Field Data ◽  
Fish Larvae ◽  
Larval Growth ◽  
Warming Trend ◽  
Mortality Rates ◽  
Larval Survival ◽  
Pelagic Fish ◽  
Balance Model ◽  
Small Pelagic Fish ◽  
Mesoscale Structures

This work develops a new method, the box-balance model (BBM), to assess the role of hydrodynamic structures in the survival of fish larvae. The BBM was applied in the northwest Mediterranean to field data, on 2 small pelagic fish species whose larvae coexist in summer: Engraulis encrasicolus, a dominant species, and Sardinella aurita, which is expanding northwards in relation to sea warming. The BBM allows one to quantify the contribution of circulation, with significant mesoscale activity, to the survival of fish larvae, clearly separating the effect of transport from biological factors. It is based on comparing the larval abundances at age found in local target areas, associated with the mesoscale structures (boxes), to those predicted by the overall mortality rate of the population in the region. The application of the BBM reveals that dispersion/retention by hydrodynamic structures favours the survival of E. encrasicolus larvae. In addition, since larval growth and mortality rates of the species are required parameters for application of the BBM, we present their estimates for S. aurita in the region for the first time. Although growth and mortality rates found for S. aurita are both higher than for E. encrasicolus, their combined effect confers a lower survival to S. aurita larvae. Thus, although the warming trend in the region would contribute to the expansion of the fast-growing species S. aurita, we can confirm that E. encrasicolus is well established, with a better adapted survival strategy.

scholarly journals Changes in the Microbiome of Mariculture Feed Organisms after Treatment with a Potentially Probiotic Strain of Phaeobacter inhibens

2020 ◽  
Vol 86 (14) ◽  
Author(s):  
Karen K. Dittmann ◽  
Bastian Barker Rasmussen ◽  
Jette Melchiorsen ◽  
Eva C. Sonnenschein ◽  
Lone Gram ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Fish Larvae ◽  
Antagonistic Effect ◽  
Rrna Gene ◽  
Fish Pathogens ◽  
Content Type ◽  
Live Feed ◽  
The Impact ◽  
Phaeobacter Inhibens

ABSTRACT The Phaeobacter genus has been explored as probiotics in mariculture as a sustainable strategy for the prevention of bacterial infections. Its antagonistic effect against common fish pathogens is predominantly due to the production of the antibacterial compound tropodithietic acid (TDA), and TDA-producing strains have repeatedly been isolated from mariculture environments. Despite many in vitro trials targeting pathogens, little is known about its impact on host-associated microbiomes in mariculture. Hence, the purpose of this study was to investigate how the addition of a TDA-producing Phaeobacter inhibens strain affects the microbiomes of live feed organisms and fish larvae. We used 16S rRNA gene sequencing to characterize the bacterial diversity associated with live feed microalgae (Tetraselmis suecica), live feed copepod nauplii (Acartia tonsa), and turbot (Scophthalmus maximus) eggs/larvae. The microbial communities were unique to the three organisms investigated, and the addition of the probiotic bacterium had various effects on the diversity and richness of the microbiomes. The structure of the live feed microbiomes was significantly changed, while no effect was seen on the community structure associated with turbot larvae. The changes were seen primarily in particular taxa. The Rhodobacterales order was indigenous to all three microbiomes and decreased in relative abundance when P. inhibens was introduced in the copepod and turbot microbiomes, while it was unaffected in the microalgal microbiome. Altogether, the study demonstrates that the addition of P. inhibens in higher concentrations, as part of a probiotic regime, does not appear to cause major imbalances in the microbiome, but the effects were specific to closely related taxa. IMPORTANCE This work is an essential part of the risk assessment of the application of roseobacters as probiotics in mariculture. It provides insights into the impact of TDA-producing Phaeobacter inhibens on the commensal bacteria related to mariculture live feed and fish larvae. Also, the study provides a sequencing-based characterization of the microbiomes related to mariculture-relevant microalga, copepods, and turbot larvae.

The influence of diet on the microbiota of live-feed rotifers (Brachionus plicatilis) used in commercial fish larviculture

2020 ◽  
Vol 367 (2) ◽  
Author(s):  
Emre Turgay ◽  
Terje Marken Steinum ◽  
Kamil Mert Eryalçın ◽  
Remziye Eda Yardımcı ◽  
Süheyla Karataş
Keyword(s):  
Brachionus Plicatilis ◽  
Fish Larvae ◽  
Bacterial Species ◽  
Alpha Diversity ◽  
Amplicon Sequencing ◽  
Rrna Gene ◽  
Fish Pathogens ◽  
Study Objective ◽  
Commercial Fish ◽  
Live Feed

ABSTRACT Live-feed is indispensable to commercial fish larviculture. However, high bacterial loads in rotifers could pose a biosecurity risk. While this may be true, live-feed associated bacteria could also be beneficial to fish larvae through improved feed utilization or pathogen inhibition following host microbiota modification. The study objective was to elucidate the largely unexplored microbiota of rotifers propagated on five different diets through bacterial community profiling by 16S rRNA gene amplicon sequencing. Investigated rotifer samples had a median observed alpha-diversity of 338 ± 87 bacterial species. Alpha- and Gamma-Proteobacteria dominated the rotifer microbiota followed by members of classes Flavobacteriia, Cytophagia, Mollicutes, Phycisphaerae and Bacteroidia. Different diets significantly altered the bacterial communities associated with rotifers according to PERMANOVA test results and beta dispersion calculations. A common core rotifer microbiome included 31 bacterial species present in relative abundances over 0.01%. We discuss the functional role of some microbiome members. Our data suggested the presence of several known fish pathogens in stock rotifers. However, we found no evidence for increased loads of these presumptive taxa in propagated live-feed rotifers during this field trial.

scholarly journals Total lipids content and fatty acids composition of the rotifer Brachionus plicatilis using artificial enrichments

2018 ◽  
Vol 68 (2) ◽  
pp. 181 ◽  
Author(s):  
J. A. THEODOROU
Keyword(s):  
Nutritional Value ◽  
Brachionus Plicatilis ◽  
Fish Larvae ◽  
Larval Growth ◽  
Total Lipids ◽  
Pufa Content ◽  
Live Feed ◽  
Significant Toxicity ◽  
Optimal Value ◽  
Rotifer Brachionus Plicatilis

Secondary feeding with commercial lipids enrichments such as the microencapsulated diets Diet A (33.42±3.00%) and Diet B (55.88±3.5%) compared with the marine yeast type product Diet C(8.59±1.0%) as a method of increasing the total lipids and ω-3 PUFA content of rotifers, hence enhancing their nutritional value as live feed prey for fish larvae in hatcheries. The total lipids the rotifers was affected analogous to the levels of these components in the feeds showing its maximum percentage uptake within 4 hours from the enrichment (20.27±3.52, 26.64±3.91, 11.31±2.30 respectively). There was not any significant toxicity to the animals due to the diets during the 16 hours experiment. The DHA/EPA for Diet A(1.31), Diet B(0.42) and Diet C(absent) as well as the DHA/EPA/ARA ratios for Diet A(10.70 ± 1.60 / 8.18 ± 1.10 / 2.08 ± 0.20), Diet B(6.20 ± 2.30 / 14.60 ±1.00 / 1.12 ± 0.40) and Diet C (0 / 5.14 ± 3.40 / 1.30 ± 1.10) indicates that Diet A is closer to the suggested DHA/EPA/ARA optimal value 10/5/1 for marine fish larval growth.

Temperature-dependent larval survival and growth differences among populations of Murray cod (Maccullochella peelii)

2019 ◽  
Vol 70 (4) ◽  
pp. 459
Author(s):  
D. P. Svozil ◽  
R. K. Kopf ◽  
R. J. Watts ◽  
A.O. Nicholls
Keyword(s):  
Standard Length ◽  
Fish Larvae ◽  
Survival Rates ◽  
High Water ◽  
Larval Survival ◽  
Southern Region ◽  
Future Climate Change ◽  
Geographical Differences ◽  
Growth And Survival ◽  
Murray Cod

Different populations of organisms can vary widely in their responses to environmental conditions and this variation is fundamental to the persistence of species. Using a common garden experiment, we examined temperature-specific growth and survival responses of larvae among populations of Murray cod (Maccullochella peelii) from four regions of the Murray–Darling Basin (MDB), Australia. Fish larvae from the four regions differed significantly in their growth and survival responses at high water temperatures ≥26°C. At 30°C, survival rates of larvae by Day 20 ranged from 0% in the Lachlan region to 82% in the southern region. Opposite to the geographical differences in survival, growth of larvae was highest in the Lachlan (14.8–15.4-mm standard length 95% CI) and lowest in the southern region (13.4–13.9-mm standard length 95% CI) at 26°C where sufficient numbers survived for comparison. Geographical differences in growth and survival responses did not follow a consistent latitudinal gradient as observed for other species, but were closely linked with previously described genetic structure. Our results suggest that the upper thermal limit of M. peelii larvae is near common river temperatures in the MDB and that maintaining functional response diversity and underlying genetic diversity will be important for ensuring the resilience of this apex predator under future climate change.

Development of Peptides that Inhibit Aminoglycoside-Modifying Enzymes and β-Lactamases for Control of Resistant Bacteria

2020 ◽  
Vol 21 (10) ◽  
pp. 1011-1026
Author(s):  
Bruna O. Costa ◽  
Marlon H. Cardoso ◽  
Octávio L. Franco
Keyword(s):  
Drug Target ◽  
Bacterial Infections ◽  
Antimicrobial Agents ◽  
Treatment Strategies ◽  
Resistance Mechanisms ◽  
Resistant Bacteria ◽  
Specific Chemical ◽  
Target Interaction ◽  
Multiresistant Bacteria ◽  
Acute Bacterial Infections

: Aminoglycosides and β-lactams are the most commonly used antimicrobial agents in clinical practice. This occurs because they are capable of acting in the treatment of acute bacterial infections. However, the effectiveness of antibiotics has been constantly threatened due to bacterial pathogens producing resistance enzymes. Among them, the aminoglycoside-modifying enzymes (AMEs) and β-lactamase enzymes are the most frequently reported resistance mechanisms. AMEs can inactivate aminoglycosides by adding specific chemical molecules in the compound, whereas β-lactamases hydrolyze the β-lactams ring, preventing drug-target interaction. Thus, these enzymes provide a scenario of multidrug-resistance and a significant threat to public health at a global level. In response to this challenge, in recent decades, several studies have focused on the development of inhibitors that can restore aminoglycosides and β-lactams activity. In this context, peptides appear as a promising approach in the field of inhibitors for future antibacterial therapies, as multiresistant bacteria may be susceptible to these molecules. Therefore, this review focused on the most recent findings related to peptide-based inhibitors that act on AMEs and β-lactamases, and how these molecules could be used for future treatment strategies.

scholarly journals Multiresistant Bacteria Isolated from Intestinal Faeces of Farm Animals in Austria

Antibiotics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 466
Author(s):  
Herbert Galler ◽  
Josefa Luxner ◽  
Christian Petternel ◽  
Franz F. Reinthaler ◽  
Juliana Habib ◽  
...  
Keyword(s):  
Meat Products ◽  
Animal Husbandry ◽  
Multidrug Resistant ◽  
Farm Animals ◽  
Resistant Bacteria ◽  
Antibiotic Resistant Bacteria ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Multiresistant Bacteria ◽  
Vancomycin Resistant

In recent years, antibiotic-resistant bacteria with an impact on human health, such as extended spectrum β-lactamase (ESBL)-containing Enterobacteriaceae, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE), have become more common in food. This is due to the use of antibiotics in animal husbandry, which leads to the promotion of antibiotic resistance and thus also makes food a source of such resistant bacteria. Most studies dealing with this issue usually focus on the animals or processed food products to examine the antibiotic resistant bacteria. This study investigated the intestine as another main habitat besides the skin for multiresistant bacteria. For this purpose, faeces samples were taken directly from the intestines of swine (n = 71) and broiler (n = 100) during the slaughter process and analysed. All samples were from animals fed in Austria and slaughtered in Austrian slaughterhouses for food production. The samples were examined for the presence of ESBL-producing Enterobacteriaceae, MRSA, MRCoNS and VRE. The resistance genes of the isolated bacteria were detected and sequenced by PCR. Phenotypic ESBL-producing Escherichia coli could be isolated in 10% of broiler casings (10 out of 100) and 43.6% of swine casings (31 out of 71). In line with previous studies, the results of this study showed that CTX-M-1 was the dominant ESBL produced by E. coli from swine (n = 25, 83.3%) and SHV-12 from broilers (n = 13, 81.3%). Overall, the frequency of positive samples with multidrug-resistant bacteria was lower than in most comparable studies focusing on meat products.

scholarly journals Prevalence And Characterization Of Plasmid-Mediated Quinolone Resistance In Various Aquatic Sources

2021 ◽  
Author(s):  
Farhan Yusuf ◽  
Kimberley Gilbride
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Quinolone Resistance ◽  
Resistant Bacteria ◽  
Rrna Gene ◽  
Environmental Isolates ◽  
Topoisomerase Iv ◽  
Phenotypic Resistance ◽  
Ciprofloxacin Resistance

Bacterial isolates found in aquatic ecosystems often carry antibiotic resistance genes (ARGs). These ARGs are often found on plasmids and transposons, which allows them to be proliferate throughout bacterial communities via horizontal gene transfer (HGT) causing dissemination of multidrug resistance. The increase in antibiotic resistance has raised concerns about the ability to continue to use these drugs to fight infectious diseases. Novel synthetic antibiotics like ciprofloxacin that are not naturally found in the environment were developed to prevent resistances. However, ciprofloxacin resistance has occurred through chromosomal gene mutations of type 2 topoisomerases or by the acquisition of plasmid-mediated quinolone resistances (PMQR). A particular PMQR, qnr genes, encoding for pentapeptide repeat proteins that confer low levels of quinolone resistance and protect DNA gyrase and topoisomerase IV from antibacterial activity. These qnr genes have been identified globally in both clinical and environmental isolates. The aim of this study was to determine the prevalence of ciprofloxacin-resistant bacteria in aquatic environments in the Greater Toronto Area and the potential dissemination of ciprofloxacin resistance. With the selective pressure of ciprofloxacin, we hypothesize that ciprofloxacin-resistant bacteria (CipR) in the environment may carry PMQR mechanisms while the sensitive population (CipS) would not carry PMQR genes. Isolates were tested for resistance to an additional 12 different antibiotics and identified using Sanger sequencing PCR products of the 16S rRNA gene. To determine which genes are responsible for ciprofloxacin resistance, multiplex PCR of associated qnr genes, qnrA, qnrB, and qnrS, was carried out on 202 environmental isolates. Our data demonstrate a similar prevalence of qnr genes was found in CipR (19%) and CipS (14%) populations suggesting that the presence of these genes was not necessarily correlated with the phenotypic resistance to the antibiotic. Furthermore, ciprofloxacinresistant bacteria were found in all locations at similar frequencies suggesting that resistance genes are widespread and could possibly arise through HGT events. Overall, determining the underlying cause and prevalence of ciprofloxacin resistance could help re-establish the effectiveness of these antimicrobial compounds.

scholarly journals Red Cusk-Eel (Genypterus chilensis) Gut Microbiota Description of Wild and Aquaculture Specimens

2022 ◽  
Vol 10 (1) ◽  
pp. 105
Author(s):  
Jaime Romero ◽  
Osmán Díaz ◽  
Claudio D. Miranda ◽  
Rodrigo Rojas
Keyword(s):  
Intestinal Microbiota ◽  
High Throughput Sequencing ◽  
Acid Synthesis ◽  
Intestinal Content ◽  
Meat Production ◽  
Rrna Gene ◽  
Potential Contribution ◽  
Ion Torrent ◽  
The 16S Rrna Gene ◽  
Genypterus Chilensis

Chile has promoted the diversification of aquaculture and red cusk-eel (Genypterus chilensis) is one of the prioritized species. However, many aspects of the biology of the species are unknown or have little information available. These include intestinal microbiota, an element that may play an important role in the nutrition and defense of cultured animals for meat production. This study compares the microbiota composition of the intestinal contents of wild and aquaculture fish to explore the microbial communities present and their potential contribution to the host. DNA was extracted from the intestinal content samples and the V4 region of the 16S rRNA gene was amplified and sequenced using the Ion Torrent platform. After the examination of the sequences, strong differences were found in the composition at the level of phylum, being Firmicutes and Tenericutes the most abundant in aquaculture and wild condition, respectively. At the genus level, the Vagococcus (54%) and Mycoplasma (97%) were the most prevalent in the microbial community of aquaculture and wild condition, respectively. The evaluation of predicted metabolic pathways in these metagenomes showed that in wild condition there is an important presence of lipid metabolism belonging to the unsaturated fatty acid synthesis. In the aquaculture condition, the metabolism of terpenoids and polyketides were relevant. To our knowledge, this is the first study to characterize and compare the intestinal microbiota of red cusk-eel (Genypterus chilensis) of wild and aquaculture origin using high-throughput sequencing.

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