Single and combined genotoxic and cytotoxic effects of two xenobiotics widely used in intensive aquaculture

Algae-Mediated Removal of Prevalent Genotoxic Antibiotics: Molecular Perspective on Algae-Bacteria Consortia and Bioreactor-Based Strategies

Antibiotic pollution poses a potential risk of genotoxicity, as antibiotics released into the environment can induce DNA damage and mutagenesis in various organisms. This pollution, stemming from pharmaceutical manufacturing, agriculture, and improper disposal, can disrupt aquatic ecosystems and potentially impact human health through the consumption of contaminated water and food. The removal of genotoxic antibiotics using algae-mediated approaches has gained considerable attention due to its potential for mitigating the environmental and health risks associated with these compounds. The paper provides an in-depth examination of the molecular aspects concerning algae and bioreactor-driven methodologies utilized for the elimination of deleterious antibiotics. The molecular analysis encompasses diverse facets, encompassing the discernment and profiling of algae species proficient in antibiotic degradation, the explication of enzymatic degradation pathways, and the refinement of bioreactor configurations to augment removal efficacy. Emphasizing the significance of investigating algal approaches for mitigating antibiotic pollution, this paper underscores their potential as a sustainable solution, safeguarding both the environment and human health.

miRNA-seq analysis of liver tissue from largemouth bass (Micropterus salmoides) in response to oxytetracycline and enzyme-treated soy protein

The specific miRNA regulation triggered by enzyme-treated soybean protein in response to well-known stressors, such as the prophylactic use of the antimicrobial oxytetracycline, remains unknown. Hence, this study aimed to evaluate the regulatory changes of hepatic miRNAs induced by oxytetracycline and enzyme-treated soybean protein in largemouth bass dietary formulations. The experiment was designed with three groups: the normal control (NC), the oxytetracycline exposure treatment group (OTC), and the pre-treatment with enzyme-treated soybean protein before oxytetracycline exposure group (ETSP). miRNA sequencing was employed to characterize the differences between these groups. In conclusion, the NC group exhibited up-regulation of 13 host miRNAs and down-regulation of 1 miRNA compared to the OTC group, whereas the ETSP group showed an increasing trend of 36 host miRNAs and a decreasing trend of 13 host miRNAs compared to the OTC group. Nine miRNAs were identified as prudential targets for enzyme-treated soy protein, protecting the largemouth bass liver from oxytetracycline. Furthermore, gene ontology analysis revealed nine key miRNAs that mediate signaling pathways with significant differences. The cellular lipid metabolic process was identified as the most important biological process, and the propanoate metabolism pathway was highlighted as significant. These results will facilitate further exploration of the mechanism by which enzyme-treated soy protein alleviates the effects of oxytetracycline on largemouth bass in water environments.

Atlantic Salmon (Salmo salar) bacterial and viral innate immune responses are not impaired by florfenicol or tetracycline administration

Antibiotics are used to treat bacterial infections in fish aquaculture, and these drugs can interact with immune cells/the immune system and potentially leave fish vulnerable to viral, fungal, parasitic, or other bacterial infections. However, the effects of antibiotics on fish immunity have largely been overlooked by the aquaculture industry. We tested, at 12 and 20 °C, whether tetracycline and florfenicol (the most commonly used antibiotics in commercial aquaculture), affected the Atlantic salmon's capacity to respond to bacterial or viral stimulation. Atlantic salmon were acclimated to 12 or 20 °C and fed with tetracycline or florfenicol (100 and 10 mg kg of body weight^-1 day^-1, respectively) medicated feed for 15 or 10 days, respectively. Thereafter, we evaluated their immune function prior to, and after, an intraperitoneal injection of Forte Micro (containing inactivated cultures of Aeromonas salmonicida, Vibrio anguillarum, Vibrio ordalii and Vibrio salmonicida) or the viral mimic polyriboinosinic polyribocytidylic acid (pIC). We measured the transcript expression levels of 8 anti-bacterial and 8 anti-viral putative biomarker genes, and the innate (leukocyte respiratory burst, plasma lysozyme activity and hemolytic activity of the alternative complement pathway) and cellular (relative number of erythrocytes, lymphocytes and thrombocytes, and granulocytes such as monocytes and neutrophils) responses to these challenges. Overall, we only found a few minor effects of either tetracycline or florfenicol on immune gene expression or function at either temperature. Although several studies have reported that antibiotics may negatively affect fish immune responses, our results show that industry-relevant dietary tetracycline and florfenicol treatments do not substantially impact the salmon's innate immune responses. Currently, this is the most comprehensive study on the effects of antibiotics administrated according to industry protocols on immune function in Atlantic salmon.

Assessing the ecological risk of active principles used currently by freshwater fish farms

The global aquaculture industry has grown exponentially in recent years using to control of infections and diseases, a variety of veterinary drugs (VMP) are used, including antibiotics, antifungals and antiparasitics, which have different routes of emission, environmental persistence and side effects to aquatic organisms, becoming one of the main concerns in its use of veterinary drugs (VMP) and its potential toxicological impact on the environment, in this context, Chile is considered one of the main salmon producers. Ecological risk assessment of active principles used infreshwater fish farms worldwide and in Chile were investigated. We recollect a physical - chemical properties of active principles used by fish farms and we could estimate the relative hazard a priori. Later active principles grouped as antibiotics (n = 6), antiparasitics (n = 5), anesthetics (n = 3), and disinfectants (n = 7) were assessed using a mass balance model based on fugacity was developed for each active principle under treatments via immersion and food administration in fish, while a volumetric model for disinfectants and sodium chloride was used for estimating the predicted environmental concentration (PEC), under a real smolt farming scenario in fish farms. Ecotoxicological data were collected from open literature to predict the no-effect concentration (PNEC). The ecological risk assessment was characterized using a risk quotient (RQ = PEC/PNEC) based in two assessment tiers. Results revealed that 12 active ingredients showed a high risk (RQ ≥ 1), thus indicating that adverse effects could occur and further investigation with measured concentrations in the field are required to reduce exposure in surface waters.

The Impact of Intensive Fish Farming on Pond Sediment Microbiome and Antibiotic Resistance Gene Composition

Aquaculture is a fast-growing animal food sector, and freshwater fish farming is particularly common in Central and Eastern Europe. As the biodiversity of fishery ponds is changed toward fulfilling the industrial needs, precautions should be taken to keep the system sustainable and protect the adjacent environment from possible damage. Due to risk of infectious diseases, antibiotics are used in aquaculture production systems. The constant exposure to antimicrobials can contribute to the rise of antibiotic resistance in aquaculture products and the adjacent ecosystems, with possibility of dissemination to the wider environment as well as between animals and humans. Even though previous studies have found antibiotic resistance genes in the sediments and water of farming ponds, the tendency and direction of spreading is not clear yet. The objective of this project was to evaluate the influence of intensive fish farming on the condition of water bodies used for the aquaculture and the environment, concentrating on the impact of the aquaculture on the surrounding water ecosystems as well as the possibility of transferring the pollutants and antibiotic resistance genes to both environment and the human hosts. Combined measurement of antibiotic and heavy metal contamination, toxicity assessment, microorganism diversity, and the detection of common antibiotic resistance genes was performed in the sediments of one fishery farm ponds as well as sampling points upstream and downstream. All the tested sediment samples did not show significantly elevated heavy metal concentrations and no substantial veterinary antibiotic pollution. From the antibiotic resistance genes tested, the presence of aminoglycoside and β-lactam resistance determinants as well as the presence of integrons could be of concern for the possibility of transfer to humans. However, despite the lack of heavy metal and antibiotic pollution, the sediments showed toxicity, the cause of which should be explored more.

Diversity of Vibrio parahaemolyticus in marine fishes of Bangladesh

AIMS

To determine the occurrence, diversity, antibiotic resistance and biofilm formation of Vibrio parahaemolyticus isolated from marine fishes in Bangladesh.

METHODS AND RESULTS

A total of 80 marine fishes were obtained from the local markets and examined for the presence of V. parahaemolyticus. All the isolated V. parahaemolyticus were characterized for the presence of virulence markers, thermostable direct hemolysin (TDH) or thermostable direct hemolysin related hemolysin (TRH). Isolates were serotyped and further characterized by enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR) typing to analyse the genetic diversity. Moreover, biofilm formation and antibiotic resistance patterns were also determined. About 63·75% (51/80) of the tested marine fishes were contaminated with V. parahaemolyticus. From the contaminated fishes, 71 representatives V. parahaemolyticus were isolated and none of them harboured tdh and trh virulence genes. Nine different O-groups and seven different K-types were found by serological analysis and the dominant serotype was O5:KUT. In ERIC-PCR analysis, eight clusters (A-H) were found and the most common pattern was A (46·5%). All of the isolates were resistant to ampicillin and 78·9% of isolates were resistant to streptomycin. The highest biofilm formation was found at 37°C compared to 25°C and 4°C.

CONCLUSION

Diverse V. parahaemolyticus are present in marine fishes in the local market of Bangladesh with antibiotic-resistant properties and biofilm formation capacity.

SIGNIFICANCE AND IMPACT OF THE STUDY

The widespread prevalence of diverse V. parahaemolyticus in marine fishes is an issue of serious concern, and it entails careful monitoring to ascertain the safety of seafood consumers.

Variation in microbial populations and antibiotic resistance genes in mariculture sediments in the present of the seaweed Ulva fasciata and under selective pressure of oxytetracycline

The widely distributed seaweed Ulva fasciata has nutrient absorption abilities and can be used in the bioremediation of polluted maricultural environments. This study explored microbial community and antibiotic resistance gene (ARG) variation in mariculture sediments in response to different trace levels (10, 100, and 500 μg L^-1) of oxytetracycline (OTC) and the presence of Ulva fasciata. The increase in OTC level promoted nutrient (NO₃_-N and PO₄^3--P) removal mainly due to Ulva fasciata adsorption. The abundances of the Euryarchaeota and Planctomycetes phyla in sediments were positively related to the increase in OTC stress, while a negative correlation occurred for the Proteobacteria phylum via metagenomic analysis. Compared with the control system, the increase rates of total ARGs were 3.90%, 7.36% and 13.42% at the OTC levels of 10, 100 and 500 μg L^-1, respectively. OTC stress mainly favoured the collateral enrichment of non-corresponding polypeptide and MLS ARGs, mainly due to the enrichment of the phyla Planctomycetes and Euryarchaeota by the synergistic effect of OTC and nutrients. The results of quantitative PCR with tetracycline resistance genes (TRGs) (tetO, tetT, tetPB, tetW and otrA) and a horizontal transfer gene (intl1) demonstrated that all of genes had much higher gene numbers in sediments after 3 months of OTC stress than in those without OTC stress, which was strongly related to the variation in the phyla Bacteroidetes, Gemmatimonadetes and Acidobacteria. The significant correlation between intl1 and the target TRGs is indicative of the important role of the horizontal transfer of integron-resistant genes in the spread of TRGs.

Antibiotic Susceptibility Testing (AST) Reports: A Basis for Environmental/Epidemiological Surveillance and Infection Control Amongst Environmental Vibrio cholerae

Distribution, investigation, surveillance and control (DISC) of cholera outbreaks in endemic/non-endemic regions has been a concerted approach towards the management of the causal pathogen. Relevant organization, government, health systems and the public have implemented several steps towards controlling the menace, yet pathogen continues to occur with diverse phenotypes/genotypes of high clinical and epidemiological relevance. The study determines antibiotic susceptibility/resistance pattern of Vibrio cholerae isolates retrieved from six domestic water sources between March and August 2018. Serological and molecular typing methods (polymerase chain reaction or PCR) were used to confirm the isolates identity. Antibiotic susceptibility testing was conducted using six commonly employed antibiotics of V. cholerae according to the recommendation of Clinical Laboratory Standard and European Committee for Antimicrobial Susceptibility Testing with other relevant antibiotics of investigative epidemiology and infection control, employing both disc diffusion test and PCR gene detection. Samples presumptive counts ranged between 1.10 to 7.91 log10 CFU/mL. Amongst the 759 presumptive isolates retrieved, sixty-one were confirmed as V. cholerae which were further serogrouped as Non-O1/Non-O139 V. cholerae. Various V. cholerae resistant phenotypes/genoytypes were detected vis: carbapenemase (CR-Vc; 31.1%/5.3%). New Delhi Metallobetalactamase (NDM-1-Vc; 23.0%/42.5%), extended spectrum betalactamase (ESBL-Vc; 42.6%/blaTEM:86,7%), chloramphenicol resistance (62.3%/Flor: 46.2%}, tetracycline resistance (70.5%/46.7%), AmpC resistance (21.0 (34.4%/56.7%)) and various other resistant genotypes/phenotypes. It was observed that more than 50% of the confirmed V. cholerae isolates possess resistance to two or more antibiotic classes/groups with multiple antibiotic resistance index (MARI) ranging from 0.031 to 0.5. This observation provides necessary information and updates for surveillance, planning and implementation of control strategies for cholera. It would also encourage decision making, formulation of policy by the government and cholera control authorities.

Antibiotic Resistance and Characteristics of Integrons in Escherichia coli Isolated from Penaeus vannamei at a Freshwater Shrimp Farm in Zhejiang Province, China

Our study was conducted to investigate the antibiotic susceptibility profiles, integrons and their associated gene cassettes (GCs), and insertion sequence common regions of Escherichia coli isolates from Penaeus vannamei collected at a large-scale freshwater shrimp farm in Zhejiang Province, People's Republic of China. A total of 182 E. coli isolates were identified from 200 samples. With the exception of imipenem, isolates were most commonly resistant to β-lactams, followed by tetracylines and sulfonamides. Fifty-two (28.6%) E. coli isolates were classified as multidrug resistant, and the patterns were highly diverse, with 29 types represented. The multiple-antibiotic resistance indices of the isolates were 0.17 to 0.56; 9.3% (17) of the 182 isolates were positive for class 1 integrons, 0.5% (1 isolate) was positive for class 2 integrons, and an insertion sequence common region 1 element was found upstream of the intI1 (integrase) gene in one of the intI1-positive isolates. Four GC arrays were detected in class 1 integrons, and one GC array was detected in class 2 integrons. Although the overall prevalence of antimicrobial-resistant bacteria in P. vannamei was lower than that previously reported for poultry and livestock farms in China, concerns about the inappropriate use of antibiotics and the transmission of antimicrobial-resistant bacteria in aquaculture were raised. Alternative approaches to reducing or replacing the use of antibiotics should be further studied.

Adverse effects of two pharmaceuticals acetaminophen and oxytetracycline on life cycle parameters, oxidative stress, and defensome system in the marine rotifer Brachionus rotundiformis

To investigate the adverse effect of two widely used pharmaceuticals, paracetamol (acetaminophen [APAP]) and oxytetracycline (OTC) on the marine rotifer Brachionus rotundiformis (B. rotundiformis), the animals were exposed to various environmentally-relevant concentrations. Up to date, acetaminophen and oxytetracycline have been considered as toxic, if used above threshold concentration, i.e. overdosed. However, this study demonstrated these two pharmaceuticals even at low concentration (i.e., μg/L scale) elicited oxidative stress through the generation of reactive oxygen species (ROS) along with the increased glutathione S-transferase activity, despite no-observed effect in in-vivo population growth. To validate the adverse effects of the two pharmaceuticals at relatively low concentrations, mRNA expression analysis was performed of the entire set of genes encoding 26 cytochrome P450s (CYPs) of phase I and 19 glutathione S-transferases (GSTs) of phase II of the rotifer B. rotundiformis. The mRNA expression analysis suggested specific genes CYP3045A2 and GSTσ1, GSTσ4, and GSTω1 take part in detoxification of APAP and OTC, resulting in no significant changes in the population growth and undetermined no observed effect concentration (NOEC) in the marine rotifer B. rotundiformis.

Discovery on Antibiotic Resistance Patterns of Vibrio parahaemolyticus in Selangor Reveals Carbapenemase Producing Vibrio parahaemolyticus in Marine and Freshwater Fish

Vibrio parahaemolyticus, a Gram-negative halophilic bacterium is often associated with fish and fishery products, thus causing gastroenteritis in humans upon ingestion of contaminated food. V. parahaemolyticus has become a globally well-known pathogen with yearly reported cases in many countries. This study aimed to discover the antibiotic resistance patterns of V. parahaemolyticus as well as detect Carbapenem resistant isolates from marine and freshwater fish in Selangor. A total of 240 freshwater and marine fish samples collected from wet market and supermarket in Selangor were tested for the presence of V. parahaemolyticus. All the fish samples were determined positive for V. parahaemolyticus using conventional microbiological culture-based method. The toxR gene were detected via polymerase chain reaction (PCR) in 165/240 (69%) isolates. The two-virulence factor of V. parahaemolyticus, thermostable direct hemolysin (tdh) and TDH-related hemolysin (trh) was screened via PCR. As such, four isolates were trh+and none were tdh+. Majority of the isolates presented high resistance to ampicillin (88%), amikacin (64%), and kanamycin (50%). In addition, this study identified 19-imipenem resistant isolates isolated from freshwater and marine fish samples. Further analysis of these 19-imipenem resistant isolates revealed that the resistance toward imipenem was plasmid mediated after plasmid curing assay. The multiple antibiotics resistance index was >0.2 for 70% of the isolates. In summary, the results confirm the presence of V. parahaemolyticus in freshwater and marine fish samples in Selangor, Malaysia. To our best knowledge, this is the first report discovering the antibiotic resistant patterns and Carbapenem-resistant isolates of V. parahaemolyticus isolated from marine and freshwater fish samples in Selangor.

Profiling bacterial communities associated with sediment-based aquaculture bioremediation systems under contrasting redox regimes

Deposit-feeding invertebrates are proposed bioremediators in microbial-driven sediment-based aquaculture effluent treatment systems. We elucidate the role of the sediment reduction-oxidation (redox) regime in structuring benthic bacterial communities, having direct implications for bioremediation potential and deposit-feeder nutrition. The sea cucumber Holothuria scabra was cultured on sediments under contrasting redox regimes; fully oxygenated (oxic) and redox stratified (oxic-anoxic). Taxonomically, metabolically and functionally distinct bacterial communities developed between the redox treatments with the oxic treatment supporting the greater diversity; redox regime and dissolved oxygen levels were the main environmental drivers. Oxic sediments were colonised by nitrifying bacteria with the potential to remediate nitrogenous wastes. Percolation of oxygenated water prevented the proliferation of anaerobic sulphate-reducing bacteria, which were prevalent in the oxic-anoxic sediments. At the predictive functional level, bacteria within the oxic treatment were enriched with genes associated with xenobiotics metabolism. Oxic sediments showed the greater bioremediation potential; however, the oxic-anoxic sediments supported a greater sea cucumber biomass. Overall, the results indicate that bacterial communities present in fully oxic sediments may enhance the metabolic capacity and bioremediation potential of deposit-feeder microbial systems. This study highlights the benefits of incorporating deposit-feeding invertebrates into effluent treatment systems, particularly when the sediment is oxygenated.

Pirimicarb-based formulation-induced genotoxicity and cytotoxicity in the freshwater fish Cnesterodon decemmaculatus (Jenyns, 1842) (Pisces, Poeciliidae)

We analyzed the aspects of lethality, genotoxicity, and cytotoxicity in the ten spotted live-bearer exposed under laboratory conditions to the pirimicarb-based formulation Patton Flow® (50% active ingredient (a.i.)). Acute effects were evaluated using different end points for lethality, genotoxicity, and cytotoxicity. Median lethal concentration (LC50) estimation was employed as a bioassay for lethality, whereas micronucleus (MN) induction and alterations in erythrocyte/erythroblast frequency were used as end points for genotoxicity and cytotoxicity, respectively. Results demonstrated an LC5096h value of 88 mg/L. Patton Flow® increased the MN frequency in fish erythrocytes after 48 h of exposure at a concentration of 66 mg/L, whereas a concentration range of 22–66 mg/L was able to exert the same genotoxic effect at 96 h of treatment. Furthermore, cytotoxicity was also observed by alterations in erythrocyte/erythroblast frequencies within the concentration range of 22–66 mg/L, regardless of the exposure time. Our current observations provide evidence that Patton Flow® (50% a.i.) should be considered a clear lethal, cytotoxic, and genotoxic agent on Cnesterodon decemmaculatus. Thus, repeated applications of this carbamic insecticide can enter the aquatic environment and exert deleterious effects on aquatic organisms other than the evaluated species C. decemmaculatus.