Shrimp Muscle Research Articles

The Activation of Endogenous Proteases in Shrimp Muscle Under Water-Free Live Transport

Water-free transportation (WFT) causes shrimp (Penaeus vannamei) flesh quality deterioration. However, the roles of endogenous protease-induced protein hydrolysis have been neglected in the research. In the present study, calpain zymography, gelatinase zymography, the hematoxylin–eosin staining method, and other methods were applied to investigate the response of various endogenous proteases (cathepsin, calpain, and gelatinase), the myofibril fragmentation index (MFI), and the microscopic morphology of shrimp muscle during WFT in comparison with the shrimp under the conventional water transportation strategy (WT). The results showed that the total activity of proteases in shrimp muscle increased significantly (p ≤ 0.05) after simulated transportation. Cathepsins and gelatinases were activated during WFT. No significant (p > 0.05) changes of the activity of caspase-3 and the muscle cell apoptosis rate were detected in shrimp muscle cells after WFT. In addition, the MFI increased and the gap among muscle fiber bundles enlarged after WFT. Compared with WFT, no significant (p > 0.05) effect on the activities of calpain, gelatinase, and caspase-3 in the muscle of shrimp was found after WT, and only the activity of cathepsin L significantly increased (p ≤ 0.05). Based on the findings, we concluded that the activation of various endogenous proteases was induced during WFT.

Morphological and Nutritional Analysis of White Shrimp, Litopenaeus setiferus, Muscle

In response to the growing seafood demand and the environmental impact of traditional aquaculture and fishing methods, this study explored the potential of cellular agriculture for sustainable seafood production. Focusing on shrimp, the most consumed seafood in the United States, our project aimed to establish a comprehensive database of the morphological and physicochemical properties of shrimp muscle. This database is intended to support the development of cell-based seafood by providing a benchmark for texture, color, and nutritional content. To do so, thirty large white shrimp (Litopenaeus setiferus) were analyzed through texture analysis, colorimetry, Hematoxylin and Eosin staining, and proximate analysis. The findings indicated consistent texture profile analysis parameters across the shrimp's surface and cross-section, while colorimetry values showed significant differences. H&E staining revealed similar cellular patterns, affirming the uniformity of shrimp texture. The proximate analysis offers a nutritional target for developing shrimp analogs. The study concludes that while shrimp texture is consistent, addressing color variation is crucial for the development of cell-based shrimp analogs. Future research should include characteristics of cooked shrimp and other seafood products to expand the database for cellular agriculture applications.

Toxicological effect of deltamethrin on enzymatical, apoptosis and immune response, histological morphology in Litopenaeus vannamei

Deltamethrin (DM) use in agricultural production and storage can result in the presence of residues in several feed ingredients, which can then be ingested by aquatic animals, potentially leading to adverse health effects. Although the potential toxicity of the lipophilic deltamethrin has been evaluated in several studies, there is a paucity of comprehensive studies on the negative effects induced by chronic exposure of shrimp to deltamethrin at different dietary lipid levels. A feeding experiment of six weeks was carried out to assess whether alterations in dietary lipid levels have an impact on the toxicity of DM. In a feeding experiment on Litopenaeus vannamei, the effects of dietary fat levels on the toxicity of DM were studied. There were six distinct diets created comprising three levels of DM (0.2 mg⋅kg–1, 1 mg⋅kg–1, 5 mg⋅kg–1), and two lipid levels (6.96 %, 10.88 %). The diets were designated as LF0.2, LF1, LF5, HF0.2, HF1, HF5. The growth performance and whole shrimp body lipid were reduced with the increase of DM addition to the diet, and DM caused abnormal changes in lipoproteins (LDL, HDL, LPS) in shrimp when feeding diets containing high doses of DM. Furthermore, GOT, GPT, AKP, and ACP activities were found to be significantly increased by long-term exposure to DM. Meanwhile, the way that genes linked to the nuclear factor kappa-B immune signaling pathway showed a significant increase in the hepatopancreas (dorsal, imd, pelle, ikkβ), intestine (imd, tube, pelle), and muscle (toll, imd, pelle) of shrimp following exposure to DM. Similarly, cellular autophagy genes in the hepatopancreas (atg9, atg12), muscle (atg3, atg9), and intestine (atg3, atg5, atg9, beclin, atg13) were significantly upregulated in a dose-dependent manner after shrimp chronic exposure to DM. Histopathological damage was also induced in the muscles under DM exposure. In summary, chronic exposure to DM resulted in a slowing of growth performance, disruption of lipoprotein metabolism, impairment of hepatopancreatic, intestinal, and muscle-related immune functions, as well as the promotion of autophagy and damage to shrimp muscle.

Role of the intestines on the muscle quality of Pacific white shrimp (Litopenaeus vannamei) during chilled storage: Physicochemical and label-free–based peptidomics analyses

The effect of shrimp deveining on the quality of Pacific white shrimp muscle was investigated by analyzing the protein degradation during chilled storage via physicochemical and label-free peptidomics analyses. In this study, shrimp with intact intestines were in the control group (CS), while deveined shrimp (DS) were in the treatment group. The total viability count (TVC), total volatile base nitrogen (TVB-N) content, and trichloroacetic acid (TCA)-soluble peptide content in all of the shrimp groups gradually increased with prolonged chilled storage. However, in the later stages of chilled storage, the DS samples exhibited significantly lower TVB-N, total bacterial, and TCA-soluble peptide contents than the CS samples, indicating that deveining treatment effectively prolonged shrimp quality. The peptidomics analysis revealed varying degrees of protein hydrolysis in the DS and CS samples during chilled storage. A total of 396 differentially abundant peptides (DAPs) were identified in the DS compared with the CS, comprising 98 upregulated and 298 downregulated segments. This suggests that the removal of the intestine effectively inhibits protein hydrolysis. Gene ontology (GO) analysis suggested that the DAPs were mainly involved in catalytic activity, binding, and metabolic processes. The cluster of orthologous groups of protein (COG) analysis showed that the cytoskeleton dynamics of the muscle proteins underwent considerable alterations influenced by the shrimp's intestines during chilled storage.

Accumulation and growth toxicity mechanisms of fluxapyroxad revealed by physiological, hepatopancreas transcriptome, and gut microbiome analysis in Pacific white shrimp (Litopenaeus vannamei)

Fluxapyroxad (FX), a typical succinate dehydrogenase inhibitor fungicide, is causing increased global concerns due to its fungicide effects. However, the accumulation and grow toxicity of FX to Litopenaeus vannamei (L. vannamei) is poorly understand. Therefore, the accumulation pattern of FX in L. vannamei was investigated for the first time in environmental concentrations. FX accumulated rapidly in shrimp muscle. Meanwhile, growth inhibition was observed and the mechanism derived by primarily accelerated glycolipid metabolism and reduced glycolipid content. Moreover, exposure to environmental concentrations of FX induced significant growth inhibition and oxidative stress and inhibited oxidative phosphorylation and TCA cycle in L. vannamei. The endocytosis signaling pathway genes were activated, thereby driving growth toxicity. Oxidative phosphorylation and cytosolic gene expression were further rescued in elimination experiments, demonstrating the mechanism of growth toxicity by FX exposure. The results revealed that FX persistently altered the gut microbiome of L. vannamei using gut microbiome sequencing, particularly with increased Garcinia Purple Pseudoalteromonas luteoviolacea for organic pollutant degradation. This study provided new insights into the potential toxicity of FX to marine organisms, emphasizing the need for further investigation and potential regulatory considerations.

Characterization of gelatin-oxidized riclin cryogels and their applications as reusable ice cubes in shrimp preservation

Traditional ice is usually employed to preserve food freshness and extend shelf life. However, ice cannot bear repeated freeze − thaw cycles during the transportation and retailing process, resulting in microbial cross-contamination and spoilage of foods. Herein, succinoglycan riclin was oxidated (RO) and crosslinked with gelatin (Ge), the Ge-RO cryogels were prepared via Schiff base reaction and three freeze − thaw cycles. The Ge-RO cryogels showed improved storage modulus (G′) and thermal stability compared with pure gelatin hydrogel. The polymer framework of Ge-RO gels exhibited stable properties against ice crystals destructions during nine freeze − thaw treatments. During the storage and repeated freeze − thaw treatments of shrimps, Ge-RO cryogels exhibited a remarkable preservation effect on shrimps, and their freshness was evaluated using an electronic nose technique equipped with ten sensors. The results demonstrated that the shrimp muscle preserved in ice generated off-odors and resulted in high sensor responses. The sensor responses were reduced sharply of shrimps preserved in cryogels. Moreover, 1H NMR-based metabolomics analysis revealed that shrimps in Ge-RO cryogels group reversed the metabolic perturbations compared with the traditional ice group, the metabolic pathways were related to energy metabolism, nucleotide metabolism, and amino acid metabolism, which provide new clues to the freshness of shrimps. Furthermore, RO exhibited superior antimicrobial activity against E. coli and S. aureus microorganisms. Thus, the crosslinked cryogels are potentially applicable to food preservation, offering sustainable and reusable solutions against traditional ice.

First report of white muscle disease caused by Photobacterium damselae subsp. damselae in Kuruma shrimp (Penaeus japonicus)

In August and September 2022, two disease outbreaks were observed in Kuruma shrimp (Penaeus japonicus) farms in Okinawa, Japan. Diseased animals exhibited clinical signs of whitened musculature extending from the abdominal to the distal region. Histopathology revealed degeneration of fibers due to liquified muscle necrosis and haemocytic infiltration. Analysis of nonhost contigs from the assembled unmapped RNA and DNA shotgun sequence reads showed significant taxonomic alignment to bacterial species. This led to the investigation of a bacterium as a possible causative agent by characterizing its population in the diseased shrimp muscle. The majority of the 16S rRNA sequence recombinant clones had their highest homology with Photobacterium sp. (> 99%). The three bacterial isolates from the whitened muscle tissue were identified as Photobacterium damselae subsp. damselae (WMD-P1, WMD-P2 and WMD-P3) by biochemical and molecular assays and were further characterized. The Pdd genomes consisted of two circular chromosomes with varying numbers of plasmid. Its size ranges from 4.47 Mb to 4.60 Mb with an average GC content of 40.8%, with predicted number of coding sequences (CDs) ranging from 3816 to 4031. hlyA and pldA genes encoding for leukocidin pore-forming toxin and phospholipase were identified. Putative virulence genes are involved in adherence, antiphagocytosis, chemotaxis and motility, iron uptake, quorum sensing, secretion system, and immune evasion. The presence of prophages, genomic islands and antimicrobial resistant genes in the Pdd genomes suggests episodes of horizontal gene transfer. Average nucleotide identity (ANI) and pangenome analyses revealed a high genetic relationship of the Pdd strains (>98%) to isolates from other sources. PCR assays validated the presence of two bacterial virulence genes encoding the pore-forming toxin and phospholipase respectively in all isolates. Also, the strains had chitinase, phospholipase, and hemolytic activities. Intramuscular injection at 1 × 108 CFU/ml bacterial concentration produced pathological signs similar to those in naturally infected shrimp after 24 hpi. Lower concentration of 1 × 103 CFU/ml resulted in morbidity after 10 dpi. These results show that P. damselae subsp. damselae (Pdd) is associated with the occurrence of white muscle disease in Kuruma shrimp.

Pharmacokinetics and Withdrawal Times of Cefotaxime in White Leg Shrimp (Litopenaeus vannamei) after Oral Administration

A high-performance liquid chromatography method coupled to tandem mass spectrometry was validated in order to study the pharmacokinetics of cefotaxime in shrimp hepatopancreases and plasma, as well as its withdrawal time related to a maximum residue limit (MRL) in shrimp muscle. Pharmacokinetics parameters were investigated through oral medication at a single dose of 25 mg/kg shrimp body weight and subsequent hepatopancreas and plasma cefotaxime concentration measurements at 0.5, 1, 2, 4, 8, 12 and 24 h after shrimp were fed with medication. The maximum concentration of cefotaxime was observed after one hour in the hepatopancreas (Cmax, 19.45 ± 2.10 mg/kg) and 4 h in plasma (0.184 ± 0.061 mg/L). Based on a minimum inhibitory concentration (MIC) of cefotaxime of 4.13 mg/L against Vibrio parahaemolyticus (known to cause acute hepatopancreatic necrosis disease (AHPND) in white leg shrimp), it was observed that the time during which the hepatopancreas cefotaxime concentration was above the MIC was 23 h. An every 24 h cefotaxime treatment could thus be effective in fighting against this bacterium in shrimp. The withdrawal time of cefotaxime was determined after shrimp were fed with medicated feed once a day and twice a day for three consecutive days. Shrimp muscle was collected on day 1 and day 3 during medication and 1, 3, 7, 14 and 21 days after medication was stopped. Considering an MRL of 50 μg/kg, the withdrawal times were 8.5 degree-days (corresponding to 6.9 h at 29.5 °C) after shrimp were fed with medicated feed once a day for 3 days and 95.5 degree-days (77.7 h at 29.5 °C) after shrimp were fed with medicated feed twice a day for 3 days. Moreover, histological analysis revealed that feeding shrimp with cefotaxime at the given dose in once- or twice-a-day treatments did not negatively impact the shrimp hepatopancreas.

Optimizing color enhancement in dried Penaeus vannamei through high-humidity hot air impingement cooking: Enzyme inactivation, reduced drying time, and Maillard reaction inhibition

This study was aimed to evaluate the potential of high-humidity hot air impingement cooking (HHAIC) on Penaeus vannamei, focusing on its drying characteristics, microstructure, water distribution, enzyme activity, astaxanthin content, antioxidant capacity, color, and Maillard reaction. Results demonstrated that a 3 min HHAIC significantly improved the shrimp's color and optimized astaxanthin content with a notable increase in scavenging capacity based on an in-vitro as antioxidation activity evaluation. Compared to the untreated samples, HHAIC could significantly inactivate polyphenol oxidase by 95.76%. Also, it suppressed the Maillard reaction by decreasing 5-hydroxymethylfurfural content and shortened the drying time by 40%. In addition, the low-field nuclear magnetic resonance and microstructure analysis showed alterations in the shrimp muscle fiber structure and water distribution. This study indicated that HHAIC could elevate quality, enhance appearance, and reduce the processing time of dried shrimp, presenting valuable implications for industry progress.

A Chelex-100-based rapid DNA extraction method and its application in the detection of shrimp pathogens

BackgroundThe Pacific white shrimp is one of the world’s most economically significant aquatic species, being one of the top three species cultured globally. However, the increasing incidence of diseases such as acute hepatopancreatic necrosis disease and hepatopancreatic microsporidia has led to a serious decline in shrimp production and severe economic losses. With the increasing demand for pathogen detection in shrimp farms, rapid DNA extraction technology has become more sophisticated. In this study, a rapid and crude method of extracting genomic DNA from shrimp muscle and hepatopancreas using Chelex-100 was established. ResultsDNA was successfully extracted from muscle and hepatopancreatic tissues using both the Chelex-100 method and commercial kits. The internal reference genes of shrimp were successfully amplified via PCR and real-time PCR using the obtained DNA samples. Moreover, a field assay was successfully conducted using real-time PCR and real-time enzymatic recombinase amplification (real-time ERA), indicating that the quality of the DNA extracted using Chelex-100 is sufficient for use in conjunction with nucleic acid amplification to detect pathogens in shrimps. ConclusionsChelex-100 is an efficient method for extracting DNA from shrimp muscle or hepatopancreas tissues, with a short extraction time, high extraction efficiency, and simple operation, making it appropriate for use in the detection of pathogens in shrimp.How to cite: Yang H, Zhou Q, Hu J, et al. A Chelex-100-based rapid DNA extraction method and its application in the detection of shrimp pathogens. Electron J Biotechnol 2024;70. https://doi.org/10.1016/j.ejbt.2024.04.004.

Developing and field testing sustainable synthetic baits for the blue crab (Callinectes sapidus) fishery

Our aim was to develop for the blue crab fishery a synthetic bait that is effective, economically viable, and made from sustainable products. Our approach was to formulate mixtures of commercially available chemicals that are proven to be feeding stimulants for crustaceans. We tested several artificial mixtures: a 32-component mixture that mimics menhaden (= Menhaden Artificial Mixture), the bait used by crab fishers; and three other artificial mixtures based on shrimp muscle that are demonstrated chemostimulants for other crustacean species. We added these artificial mixtures to a matrix to create synthetic baits that release chemicals at the same rate and duration as does menhaden bait. Laboratory behavioral studies showed that these artificial mixtures, especially Menhaden Artificial Mixture, and extracts of synthetic baits containing the artificial mixtures stimulate alerting and grabbing behaviors by crabs, though less than extracts from menhaden itself. Synthetic baits were also ingested by crabs thus demonstrating that they are palatable. However, when synthetic baits containing these artificial mixtures were tested in trapping studies in the Ogeechee and Altamaha Rivers of Georgia, they caught fewer crabs than menhaden-baited traps and no more than no-bait traps. We offer several hypotheses as to why our synthetic traps with artificial mixtures that stimulate feeding behavior in the laboratory are less effective in the field than in the laboratory.

A comparative study on the taste quality of whiteleg shrimp (Penaeus vannamei) under two different transportation strategies

The current study comprehensively investigated the impacts of simulated water-based transportation and waterless transportation on the taste attributes and nonvolatile taste components in shrimp muscle. The results of the electronic tongue revealed that the umami sensation increased while the sweetness decreased after transportation. The primary taste components of shrimp muscle from the various transportation groups were identified using two-dimensional correlation spectroscopy, including free amino acids, nucleotides, and organic acids. The highest equivalent umami concentration was observed in the waterless transportation group (18.78 g MSG/100 g), followed by the water-based transportation (15.33 g MSG/100 g) and fresh groups (12.08 g MSG/100 g). The contents of main taste-active compounds, especially umami amino acids, organic acids, Na+, Cl−, and 5′-nucleotides, were higher in the shrimp muscle of the waterless transportation group, which were more likely to be accepted and preferred. This research provided insights into improving shrimp muscle taste quality through the appropriate application of transportation strategies.

Aurantiochytrium sp. and Nannochloropsis spp. meals as substitutes for fish oil in practical diets for Pacific white shrimp Penaeus vannamei

This study aimed to evaluate the use of microalgae meal (Aurantiochytrium sp. and Nannochloropsis spp.) as a substitute for fish oil in the diet of shrimp Penaeus vannamei reared in a clear water system. In the diet of these animals, the concentration of fish oil decreased as microalgae meal was inserted, and these were used in five different substitutions: 0, 25, 50, 75, and 100%. The treatments were carried out in triplicate, and after 49 days of cultivation, the zootechnical parameters and the composition of fatty acids in the animals' muscles were analyzed. In zootechnical performance, the shrimp obtained an average final weight of 16.59 ± 0.3 g, and the growth was approximately 1.89 ± 0.30 g week-1. In addition, feed conversion was, on average, 1.47 ± 0.28, and survival was greater than 97%. However, no significant difference was observed in these parameters. Regardless of the levels of fish oil replacement by microalgae meal, the composition of fatty acids in the shrimp muscle was ensured, as well as their quantity within groups, such as n-3 and n-6 polyunsaturated fatty acids. Thus, with the results obtained in the present study, it is suggested that it is possible to formulate a high-performance diet without any ingredients of marine origin (fish oil or fish meal), contributing to aquaculture's sustainability.

Effects of different thermal sterilization conditions on the quality of ready-to-eat shrimp based on specific sterilization intensity

The effects of different thermal sterilization conditions on the quality and digestibility of ready-to-eat (RTE) shrimp were investigated. Compared with the high-temperature (121 °C) and short-time (6 min and 8 min) sterilization, the low-temperature (110 and 115 °C) and long-time (>20 min) sterilization significantly promoted the Maillard and browning reactions and changed the color of the RTE-shrimp. The high sterilization temperature promoted shrimp protein oxidation, resulting in increased carbonyl group, disulfide bond, and free radical content, while the free sulfhydryl group content decreased. This oxidation and tissue destruction at high temperature led to reduced texture properties and altered water distribution within the shrimp's muscles. However, sterilized shrimp exhibited superior digestive properties in an in vitro simulated digestion experiment. High-temperature and short-time sterilization is more effective in mitigating the quality deterioration of RTE-shrimp compared to low-temperature and long-time sterilization.

Rapid Apta-Chromogenic Detection Method for Nitrofuran Metabolite Determination.

Nitrofuran (NF) contamination in food products is a global problem resulting in the banned utilization and importation of nitrofuran contaminated products. A novel chromogenic detection method using a specific DNA aptamer with high affinity and specificity to nitrofurans was developed. Single-stranded DNA aptamers specific to nitrofuran metabolites, including 3-amino-2-oxazolidinone (AOZ), 3-amino-5-methylmorpholino-2-oxazolidinone (AMOZ), and 1-aminohydantoin (AHD), were isolated using magnetic bead-SELEX. The colorimetric detection of nitrofurans using gold nanoparticles (AuNPs) exhibited an AOZ detection range of 0.01-0.06 ppb with a limit of detection (LOD) of 0.03 ppb. At the same time, this system could detect AMOZ and AHD at a range of 0.06 ppb and 10 ppb, respectively. The fast nitrofuran extraction method was optimized for food, such as fish tissues and honey, adjusted to be completed within 3-6 h. This novel apta-chromogenic detection method could detect NF metabolites with a sensitivity below the minimum required performance limit (MPRL). This analysis will be valuable for screening, with a shortened time of detection for aquaculture products such as shrimp and fish muscle tissues.

Sourcing aliphatic and polycyclic aromatic hydrocarbons (PAHs) in Jinga shrimp (Metapenaeus affinis) muscle tissues and surface sediments (study case: Northwest Persian Gulf).

This study addresses the sources of aliphatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs) in the surface sediments of the northwestern Persian Gulf and the muscle tissues of Jinga shrimp (Metapenaeus affinis), a commercially important aquatic species. In November 2018, 28 Jinga shrimp samples were systematically collected from four key fishing areas in Behrgan and Khormusi: Imam Khomeini Port (S1), Mahshahr Port (S2), Sejafi (S3), and Behrgan Wharf (S4). Additionally, sediment samples were collected from these locations, and AHs and PAHs concentrations were analyzed using gas chromatography-mass spectrometry (GC-MS). The average aliphatic concentration in Jinga shrimp was 4800.32 (μg g-1 DW), exceeding the sediment samples' 2496.69 (μg g-1 DW) estimate. Hydrocarbon component analysis revealed EPA priority list (PAH-16) and measured PAHs (PAH-29) concentrations in Jinga shrimp ranging from 1095.8 to 2698.3 (ng g-1 DW) and in sediments from 653.6 to 1019.5 (ng g-1 DW). Elevated AHs and PAHs in Jinga shrimp, compared to sediments, suggest a petrogenic source, notably at station S4 near Behrgansar and Nowruz oil fields. Low molecular weight (LMW) compounds dominated in both shrimp and sediment PAHs. Aliphatic composition profiles in shrimps closely mirrored sediment profiles, illustrating an even-to-odd carbon dominance gradient. Diagnostic ratio examinations of hydrocarbons indicated pervasive petroleum derivatives in the environment. This study establishes a direct correlation between hydrocarbon concentrations in shrimp and sediment samples and the corresponding aliphatic groups, PAH-16, and PAH-29. The findings underscore the potential of Jinga shrimp as a reliable indicator of hydrocarbon pollution in the northwestern Persian Gulf.

Cloning and expression profile of the alanine aminotransferase gene from kuruma shrimp Penaeus japonicus exposed to different salinities.

Several crustaceans including shrimps change the amount of specific free amino acids to regulate the osmotic pressure in their bodies. Kuruma shrimp Penaeus japonicus also increases the concentration of alanine (Ala) in the abdominal muscle following the increase of environmental salinity. In the present study, to elucidate the mechanisms of changes in Ala accumulation of kuruma shrimp depending on salinity, we cloned the gene encoding alanine aminotransferase (ALT), an enzyme involved in Ala biosynthesis, and examined its expression profile. It was found that the full-length kuruma shrimp ALT1 cDNA consisted of 3,301 bp, encoding 514 amino acids, and that all amino acid residues important for ALT activity were conserved. Phylogenetic analysis also indicated that the ALT gene cloned in this study was classified as ALT1. Moreover, we examined the expression levels of the ALT1 gene in the abdominal muscle and the hepatopancreas of kuruma shrimp acclimated at17‰, 34‰, and 40‰ salinities, resulting that the mRNA levels of the ALT1 genes in both tissues of the shrimp acclimated at 40‰ were significantly higher than those at 17‰ for 12 h(p < 0.05). The mRNA levels of the ALT1 gene in the abdominal muscle of the shrimp acclimated for more than 24 htended to increase following the increase of environmental salinity. These results indicate that ALT1 is responsible for the increase of free Ala concentration in the abdominal muscle of kuruma shrimp to regulate osmotic pressure at high salinity.

Nanopore sequencing for identification and characterization of antimicrobial-resistant Escherichia coli and Salmonella spp. from tilapia and shrimp sold at wet markets in Dhaka, Bangladesh.

Wet markets in low-and middle-income countries are often reported to have inadequate sanitation resulting in fecal contamination of sold produce. Consumption of contaminated wet market-sourced foods has been linked to individual illness and disease outbreaks. This pilot study, conducted in two major wet markets in Dhaka city, Bangladesh during a 4-month period in 2021 aimed to assess the occurrence and characteristics of Escherichia coli and non-typhoidal Salmonella spp. (NTS) from tilapia (Oreochromis niloticus) and shrimp (Penaeus monodon). Fifty-four individuals of each species were collected. The identity of the bacterial isolates was confirmed by PCR and their susceptibility toward 15 antimicrobials was tested by disk diffusion. The whole genome of 15 E. coli and nine Salmonella spp. were sequenced using Oxford Nanopore Technology. E. coli was present in 60-74% of tilapia muscle tissue and 41-44% of shrimp muscle tissue. Salmonella spp. was found in skin (29%) and gills (26%) of tilapia, and occasionally in muscle and intestinal samples of shrimp. The E. coli had several Multilocus sequence typing and serotypes and limited antimicrobial resistance (AMR) determinants, such as point mutations on glpT and pmrB. One E. coli (BD17) from tilapia carried resistance genes for beta-lactams, quinolones, and tetracycline. All the E. coli belonged to commensal phylogroups B1 and A and showed no Shiga-toxin and other virulence genes, confirming their commensal non-pathogenic status. Among the Salmonella isolates, five belonged to Kentucky serovar and had similar AMR genes and phenotypic resistance patterns. Three strains of this serovar were ST198, often associated with human disease, carried the same resistance genes, and were genetically related to strains from the region. The two undetermined sequence types of S. Kentucky were distantly related and positioned in a separate phylogenetic clade. Two Brunei serovar isolates, one Augustenborg isolate, and one Hartford isolate showed different resistance profiles. This study revealed high fecal contamination levels in tilapia and shrimp sold at two main wet markets in Dhaka. Together with the occurrence of Salmonella spp., including S. Kentucky ST198, a well-known human pathogen, these results stress the need to improve hygienic practices and sanitation standards at markets to improve food safety and protect consumer health.

Novel magnetic porous organic polymer containing amino and triazine bifunctional groups for efficient adsorption of nitroimidazoles

In this paper, a novel magnetic hyper-crosslinked polymer with amino and triazine bifunctional groups (M-NH2-THCP) was developed. M-NH2-THCP has strong nitroimidazoles (NDZs) enrichment effect, and therefore it was used as an adsorbent to extract five NDZs from lake water, catfish and shrimp meat prior to HPLC. Polar interaction, π-π stacking interaction, hydrogen bond and Lewis acid-base interaction were attested to be the major adsorption mechanism. The method has a good linearity in the range of 0.1–100 ng mL−1 for lake water, 10–400 ng g−1 for catfish and shrimp muscle with R2 > 0.9964. The limits of detection of NDZs were 0.03–0.04 ng mL−1 for lake water, 1.0–2.0 ng g−1 for catfish and 2.0–2.5 ng g−1 for shrimp, which is superior to most reported method. The method recoveries were 87.6–119 %, and relative standard deviations were less than 8.7 %. M-NH2-THCP holds great application potential in pollutants enrichment, separation and removal.

Mercury content in commercial crustaceans of the Barents Sea

This study aims to identify the total mercury content in the muscle and hepatopancreas of the main commercial crustaceans from the Barents Sea.The material for this study was the samples of red king crab Paralithodes camtschaticus and northern shrimp Pandalus borealis caught during the research cruises conducted by “PINRO” from 2012 to 2022. This study examines the samples of muscle collected from crustaceans, as well as the samples of hepatopancreas collected from the red king crab.Novelty: This study involves abundant data that was used to make the first comparative analysis of the Hg concentration in red king crab and northern shrimp. A significant similarity in the levels of Hg content in the muscle of shrimp and crab at the mean level was shown. The paper provides maps of average Hg content in the studied species for the entire Barents Sea.Methods used: the total mercury content in the samples was estimated by flameless atomic absorption spectroscopy analysis using Shimadzu Cold Vapor Atomic Absorption Spectrophotometer (Japan). Statistical data processing and charting were done using MS Excel and application software package of Statistica 13.Results: The paper shows that the average concentration of Hg in the muscle and hepatopancreas of the studied hydrobionts did not exceed 0.2 mg/kg of wet weight that is the acceptable concentration established by sanitary standards. The content of Hg in the red king crab’ hepatopancreas was about 2 times higher than in the muscle. The paper makes an assumption on the species-specifity of Hg content in the red king crab’ muscle. The Hg content in the muscle of P. borealis is strongly related to its fattiness. The paper suggests calculated background levels of the total Hg concentration in the muscle of P. camtschaticus and P. borealis from the Barents Sea.Practical relevance: The results obtained were used to establish the safety compliance of commercial crustaceans with the requirements adopted in Russia.