Responses of bacterial and three sub-microeukaryote communities in the water of white shrimp Penaeus vannamei aquaculture ponds in two polyculture models.

Polyculture operations in freshwater aquaculture ponds can disrupt microbial communities. High-throughput sequencing was used to assess the impact of polyculture operations on bacterial and three sub-microeukaryote communities (fungi, zooplankton, and eukaryotic phytoplankton) in Penaeus vannamei aquaculture ponds containing oriental river prawns and giant freshwater prawns, respectively. The results showed that the bacterial community was less sensitive than the microeukaryote communities to both the polyculture activity and environmental variations. The polyculture of giant freshwater prawns rather than oriental river prawns was the primary factor affecting the beta diversity of the three sub-microeukaryote communities. This may be due to the larger biomass of the polyculture varieties of giant freshwater prawns compared with oriental river prawns. The polyculture activity of giant freshwater prawns with a higher density and that of oriental river prawns with a lower density increased the stochasticity of the community assembly of the three sub-microeukaryote communities. It also affected the topological properties of the microbial communities, including greater correlations between ecosystem elements, and reducing the correlations among zooplanktons. The eukaryotic phytoplankton was the only microbial community that could also be explained by nutrient variation (mainly the total nitrogen). This highlights the potential role of the eukaryotic phytoplankton as a suitable indicator of the effects of nutrient input into ecosystems.

Time-dependent gut microbiota analysis of juvenile Oreochromis niloticus by dietary supplementation of resveratrol.

To evaluate the changes in bacterial diversity at various time points under resveratrol supplementation, we aimed to investigate the diversification of gut microbiota and the changes in total genetic diversity. We performed 16S rDNA gene sequencing at different time points (15, 30, and 45 days) to analyze the gut microbiota of tilapia. Fusobacteria, Proteobacteria, and Bacteroidetes (15 days) or Cyanobacteria (30 and 45 days) were found to be the three most abundant phyla. Cyanobacteria (15 and 30 days), Proteobacteria (15 days), Firmicutes and Chlamydiae (30 and 45 days), Planctomycetes (30 days), Bacteroidetes, Actinobacteria, and Fusobacteria (45 days) in the 0.05 g/kg RES group increased as compared to that in the controls. Proteobacteria and Cyanobacteria significantly decreased and increased at 30 and 45 days, respectively, while the reverse pattern was observed at 15 days. The Bacteroidetes:Firmicutes and Proteobacteria:Cyanobacteria ratios were significantly increased (15 and 45 days, P < 0.05) and decreased (30 days, P < 0.05). RES supplementation did not affect the richness and diversity of the gut microbiota in tilapia. Our findings may contribute to the development of strategies for the management of diseases.

Varieties of immunity activities and gut contents in tilapia with seasonal changes.

We performed 16S rDNA sequencing of tilapia fecal samples to analyze changes in tilapia gut contents after cultivation of the fish in the presence of sandwich-like floating beds of Chinese medicinal herbs (5 and 10% planting-areas; 5% Polygonum cuspidatum). The interactive effects between water quality and blood and hepatic pro- and anti-inflammatory concentrations were also assessed. Our results showed that the water quality (i.e., NO3--N, NO2--N, TP removal rates) improved, and the abundance of Chloroflexi and Cyanobacteria increased. The abundance of Bacteroidetes, Verrucomicrobia, Saccharibacteria, and Actinobacteria showed both significant seasonal decreases and increases in the presence of P. cuspidatum (increases in August and decreases in July). Fish blood and hepatic IL-10 and IFN-γ levels (together with fish sampled in September) significantly increased in the P. cuspidatum group sampled in August, while those of TNF-α (10% sandwich-like, P. cuspidatum), IL-1ß (P. cuspidatum), IL-8 (5% sandwich-like in September, S905S) significantly decreased. Heat shock proteins 60 and 70 levels significantly increased in the P. cuspidatum group, and complement C3 and C4 concentrations significantly increased in S905S. This study demonstrated that enhanced immunity through the regulation of pro- and anti-inflammatory proteins was sustained throughout development until harvest, particularly in fish grown with P. cuspidatum.

Reshaping fecal gut microbiota composition by growing with Polygonum cuspidatum, Houttuynia cordata, and Ipomoea aquatica.

We carried out sequencing of samples cultivated in floating beds with different Chinese medicinal herbs (Control, Houttuynia cordata Thunb., Polygonum cuspidatum, and a combination of H. cordata with Ipomoea aquatica Forssk.; named groups A, B, C, D, respectively) to analyze changes in the composition of gut microbiota of tilapia feces. Fusobacteria (ranging from 49.0% to 73.3%), Firmicutes (12.3%-37.8%), and Proteobacteria (5.1%-23.0%) were found to be the most dominant phyla present in all samples. The operational taxonomic units and the Ace and Chao1 indices of groups A and D were significantly higher than those of group C. Polygonum cuspidatum decreased the species richness and diversity of microbial communities in tilapia intestinal feces. The phylum WCHB1-60, order Enterobacteriales, and genus Plesiomonas significantly decreased (in group A); the species Plesiomonas shigelloides significantly decreased (in groups B and C); and the genus Leucobacter significantly increased (in group D) when compared with the control. The relative abundance of the class Verrucomicrobiae (groups B vs C) significantly decreased. In the presence of I. aquatica, the phylum Bacteroidetes significantly decreased, while the genera Leucobacter and Pelotomaculum significantly increased. The ratio of Bacteroidetes to Firmicutes was significantly higher in groups B and C relative to the controls, while it decreased significantly in group D. The algae (i.e., Anabaena and Microcystis) and beneficial pathogenic bacteria decreased in groups C and D, respectively. In addition, Enterovibrio decreased in all treatment groups. The present data demonstrate that floating bed cultivation with Chinese medicinal herbs significantly alters the gut microbiota of tilapia, which may enhance its immune activity.

Gut microbiota analysis of juvenile genetically improved farmed tilapia (Oreochromis niloticus) by dietary supplementation of different resveratrol concentrations.

The genetically improved farmed tilapia (GIFT, Oreochromis niloticus) is cultured widely for production of freshwater fish in China, while streptococcosis, likely related to pathogenic infections, occurs frequently in juvenile, mother, and operated GIFT. The gut microbiota plays an important role in nutrient digestibility in animals, and resveratrol (RES) has been used in feed for different freshwater fish species. Therefore, understanding changes in the tilapia gut microbiota across different concentrations of dietary RES supplementation is extremely important. The gut microbiota population in tilapia at 45 d after supplementation with different concentrations (0, 0.025, 0.05, 0.1 g/kg) of dietary RES was assessed by 16S rDNA gene sequencing. A total of 5445 operational taxonomic units were identified from all samples, and 14 phyla and 81 families were identified from all fecal samples. The bacteria of the phylum Firmicutes were significantly enriched in the 0.025 g/kg RES group when compared with the controls. Proteobacteria, Firmicutes and Cyanobacteria were the most dominant three phyla in all samples. With the increasing concentrations, the proportion of beneficial microbial taxa (Acetobacteraceae and Methylobacteriaceae) increased, whereas the proportion of harmful microbial taxa decreased, eg. Streptococcaceae except for 0.1 g/kg RES groups. RES did not affect the richness and diversity in tilapia gut microbiota. These findings provide information on the diversity and differences in GIFT gut microbiota database, and may contribute to developing strategies for management of diseases and long-term sustainability of O. niloticus culture.

Methanogenic community compositions in surface sediment of freshwater aquaculture ponds and the influencing factors.

Aquaculture ponds represent ecologically relevant environments to study the community composition and diversity of methanogenic assemblages, as well as their interactions with cultivated species and chemical indicators. In this study, aquaculture ponds with crab (Eriocheir sinensis), oriental river prawn (Macrobrachium nipponense), perch (Micropterus salmonides) and Wuchang fish (Parabramis pekinensis) were sampled, and Illumina high-throughput sequencing was used to investigate the methanogenic communities. The results revealed that the abundant methanogenic orders in surface sediment were Methanomicrobiales, Methanosarcinales and Methanocellales. The relative abundance of Methanocellales was higher in crab and prawn ponds as compared to other ponds. Methanogenic 16S rRNA gene abundance and beta diversity of the community was affected by the cultivated species. Methanogenic communities in aquaculture ponds with higher contents of total nitrogen and organic matter had decreased species richness, while those with higher contents of ammonia and nitrite had an overall decreased abundance of methanogens and their respective diversities. Overall, in addition to the differences in cultivated species, the consequent differences in farming practices including the types and amounts of feeds used, the contents of total nitrogen, organic matter, ammonia and nitrite could all influence the methanogenic community in surface sediment of aquaculture ponds.

Hepatic transcriptome analysis of juvenile GIFT tilapia (Oreochromis niloticus), fed diets supplemented with different concentrations of resveratrol.

The GIFT (Genetically Improved Farmed Tilapia) tilapia, Oreochromis niloticus, is cultured widely for the production of freshwater fish in China. Streptococcosis, which is related to pathogenic infections, occurs frequently in juvenile and adult female GIFT individuals. Resveratrol (RES) has been used in feed to control these infections in freshwater tilapia. To address the effects of RES on tilapia, we used high-throughput RNA sequencing technology (RNA-Seq, HiSeq. 2500) to explore the global transcriptomic response and specific involvement of hepatic mRNA of juvenile O. niloticus fed with diets containing different concentrations of (0, 0.025, 0.05, and 0.1g/kg) RES. A total of > 24,513,018 clean reads were generated and then assembled into 23,244 unigenes. The unigenes were annotated by comparing them against non-redundant protein sequence (Nr), non-redundant nucleotide (Nt), Swiss-Prot, Pfam, Gene Ontology database (GO), Clusters of Orthologous Groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, and 12,578 unigenes were annotated to the GO database. A total of 1444 (0.025g/kg RES), 1526 (0.05g/kg RES), and 3135 (0.1g/kg RES) genes were detected as significant differentially expressed genes (DEGs), when compared with the controls. A total of 6 (0.025 vs 0.05g/kg RES), 19 (0.025 vs 0.1g/kg RES), and 124 (0.05 vs 0.1g/kg RES) genes were detected as significant DEGs. Six genes, including dnah7x1, sox4, fam46a, hsp90a, ddit4, and nmrk2, were associated with an immune response. These findings provide information on the innate immunity of GIFT and might contribute to the development of strategies for the effective management of diseases and long-term sustainability of O. niloticus culture.

Archaeal community compositions in tilapia pond systems and their influencing factors.

Archaea, like the bacterial communities are gradually being realized as key players in the biogeochemical progress of water ecosystems. In this study, tilapia aquaculture ponds were used for an in-depth understanding of archaeal community compositions in water and surface sediment. Some of the main functions, as well as the communities' response patterns, to time variations, pond differences and some physio-chemical parameters were investigated. The results revealed the dominant phylum in both the water and surface sediment, as Euryarchaeota, while, the most abundant classes were: Halobacteria and Methanomicrobia respectively. Significant differences in the archaeal community compositions in the water and surface sediment, were observed in the early stages of cultivation, which became minimal at the later stage of the GIFT tilapia cultivation. Additionally to the differences in the most abundant classes, more OTUs were observed in water samples than in surface sediment samples. The methane generation could be attributed to the large proportion of methanogens found in both pond water and in the surface sediment. Furthermore, the archaeal community compositions in water and the surface sediment were shaped mainly by temporal variations and pond differences respectively. In the pond water, the archaeal community compositions were highly co-related to the concentration changes of ammonia, sulfate and total nitrogen; while in the surface sediment, the correlation to the content changes was significant in total phosphorus. The archaeal community compositions in surface sediment should be considered as an indicator for future environmental capacity studies in aquaculture.

Dietary risk ranking for residual antibiotics in cultured aquatic products around Tai Lake, China.

Antibiotics are widely used in aquaculture and therefore may be present as a dietary risk in cultured aquatic products. Using the Tai Lake Basin as a study area, we assessed the presence of 15 antibiotics in 5 widely cultured aquatic species using a newly developed dietary risk ranking approach. By assigning scores to each factor involved in the ranking matrices, the scores of dietary risks per antibiotic and per aquatic species were calculated. The results indicated that fluoroquinolone antibiotics posed the highest dietary risk in all aquatic species. Then, the total scores per aquatic species were summed by all 15 antibiotic scores of antibiotics, it was found that Crab (Eriocheir sinensis) had the highest dietary risks. Finally, the most concerned antibiotic category and aquatic species were selected. This study highlighted the importance of dietary risk ranking in the production and consumption of cultured aquatic products around Tai Lake.

Effect of methomyl on sex steroid hormone and vitellogenin levels in serum of male tilapia (Oreochromis niloticus) and recovery pattern.

Tilapia were exposed to sub-lethal concentrations of 0, 0.2, 2, 20 or 200 µg/L for 30 days, then transferred to methomyl-free water for 18 days. E2 , T, 11-KTand VTG in serum were examined. There were no significant changes in all the parameters in serum of tilapia exposed to 0.2 µg/L and 2 µg/L methomyl compared to the control. However, 20 µg/L and 200 µg/L have the potential to disrupt the endocrine system of male tilapia, as shown by its ability to increase VTG and E2 and decrease T and 11-KT in serum. Thus it would appear the no observed adverse effect level for sexual steroid hormones of methomyl is lower than 2 µg/L. Recovery data showed that the effects produced by 20µg/L were reversible but not at 200µg/L. Furthermore, the sensitivity of above parameters to methomyl followed the order of VTG>E2 >11-KT>T>GSI, suggesting VTG being the better biomarkers.

Characterizing bacterial communities in tilapia pond surface sediment and their responses to pond differences and temporal variations.

Bacterial community compositions in the surface sediment of tilapia ponds and their responses to pond characteristics or seasonal variations were investigated. For that, three ponds with different stocking densities were selected to collect the samples. And the method of Illumina high-throughput sequencing was used to amplify the bacterial 16S rRNA genes. A total of 662, 876 valid reads and 5649 operational taxonomic units were obtained. Further analysis showed that the dominant phyla in all three ponds were Proteobacteria, Bacteroidetes, Chloroflexi, and Acidobacteria. The phyla Planctomycetes, Firmicutes, Chlorobi, and Spirochaetae were also relatively abundant. Among the eight phyla, the abundances of only Proteobacteria, Bacteroidetes, Firmicutes, and Spirochaetae were affected by seasonal variations, while seven of these (with the exception of Acidobacteria) were affected by pond differences. A comprehensive analysis of the richness and diversity of the bacterial 16S rRNA gene, and of the similarity in bacterial community composition in sediment also showed that the communities in tilapia pond sediment were shaped more by pond differences than by seasonal variations. Linear discriminant analysis further indicated that the influences of pond characteristics on sediment bacterial communities might be related to feed coefficients and stocking densities of genetically improved farmed tilapia (GIFT).

Environment consistently impact on aquaculture: The predominant source of residual pollutants in cultured Chinese mitten crab (Eriocheir sinensis) across China.

Advancements in monitoring and operation of aquaculture environments has minimized the concentrations of some residual pollutants in cultured aquatic products. However, currently most aquatic products are "farmed", and relationships among residual pollutants in tissues of crabs were still unclear. In this study, 64 typical pollutants, including 25 antibiotics, 15 metal, 23 organochlorine pesticides, and one dioxin-like compound inducing hydrocarbon-receptor (AHR) activity were measured in Chinese mitten crab (Eriocheir Sinensis) risks of consumption assessed and ranked. The superposition of properties including severity and relative potency of effects and parameters describing persistence and exposure along with rates of usage and identification of groups most likely to be exposed were assessed in combination to rank likelihood of dietary exposure and probabilities of adverse effects for each contaminant. The results indicated that the total scores per pollutants found that Cadmium (Cd), Heptachlor epoxide (HEPE), dioxin TEQ exhibited the greatest scores and explained the severity of dietary risk, while source analysis found that the three main pollutants resulted from the ambient environment and are not due to specific aquaculture processes. In summary, environment is still the predominant source of residual pollutants in cultured Chinese mitten crab across China.

Assessment of the benefits of essential fatty acids and risks associated with antimicrobial residues in aquatic products: A case study of Chinese mitten crab (Eriocheir sinensis).

Much attention has been given to the safety and quality of aquatic products, including consuming Chinese mitten crab (Eriocheir sinensis), which offers both nutritional benefits and toxicological risks. Eighteen sulfonamides, 9 quinolones and 37 fatty acids were analyzed in 92 crab samples from primary aquaculture provinces in China. Enrofloxacin and ciprofloxacin have been mentioned as typical antimicrobials occurring at the greatest concentrations (>100 µg/kg, wm). By use of an in vitro method, the proportions of enrofloxacin, ciprofloxacin and essential fatty acids (EFAs, DHA and EPA) in ingested nutrients were determined to be 12 %, none and 95 %, respectively. The risk-benefit quotient (HQ) between the adverse effects of antimicrobials and nutritional benefits of EFAs in crabs found that HQs based on data after digestion were significantly less (HQ = 0.0086) than that of the control group where no digestion occurred (HQ = 0.055). This result suggested that (1) there was less risk posed by antimicrobials due to the consumption of crab, and (2) ignoring the bioaccessible fraction of antimicrobials in crabs might overestimate risks to the health of humans due to dietary exposure. Meaning bioaccessibility can improve the accuracy of the risk assessment process. Realistic risk evaluation should be recommended to achieve a quantified assessment of the dietary risks and benefits of aquatic products.

The Gill-Associated Bacterial Community Is More Affected by Exogenous Chlorella pyrenoidosa Addition than the Bacterial Communities of Water and Fish Gut in GIFT Tilapia (Oreochromis niloticus) Aquaculture System.

Microalgae has been widely used in aquaculture to improve both the water environment and fish growth; however, the current understanding of the effects of microalgae addition on the key players involved in regulating the water environment and fish health, such as microorganisms, remains limited. Here, a 50-day mesocosm experiment was set up to simulate the culture of Genetic Improvement of Farmed Tilapia (GIFT, Oreochromis niloticus) with an average weight of 14.18 ± 0.93 g and an average length of 82.77 ± 2.80 mm. Different amounts of Chlorella pyrenoidosa were added into these artificial systems to investigate dynamics of bacterial communities in aquaculture water, fish gill, and gut using amplicon-based high-throughput sequencing technology. Our results showed that Chlorella pyrenoidosa addition increased diversity and network complexity of gill-associated bacterial communities rather than those of the water and gut. Furthermore, more biomarkers in the gill-associated bacterial communities were detected in response to Chlorella pyrenoidosa addition than the water and fish gut samples. These findings highlighted the high sensitivity of gill-associated bacterial communities in response to the Chlorella pyrenoidosa addition, implying Chlorella pyrenoidosa addition could play important roles in regulating the fish mucosal immunity by altering the gill-associated microbiota.

Quantitative benefit and risk assessment of cadmium and nutrient levels in Chinese mitten crab (Eriocheir sinensis).

The use of Chinese mitten crabs for human consumption is controversial due to their uptake of heavy metals, such as cadmium (Cd). We developed a formula for quantification of benefit and risk assessment (hazard quotient) for the intake of a product containing essential polyunsaturated fatty acids versus heavy metals. A total of 70 samples (2100 individuals) of crabs were collected from 6 representative basins in Jiangsu province to determine Cd levels. Cd levels ranged from 0.028 to 5.015 mg kg-1, and the levels among the basin regions were similar (p > 0.05). To determine the nutritional differences between crabs fed with iced trash fish and formulated feed, we conducted a comparative aquaculture experiment. We simulated the cultivation conditions of crabs in China and found that the nutritional content in the trash fish group (28.724 ± 2.301 mg kg-1) was significantly higher than in the formulated food group (19.278 ± 3.556 mg kg-1; p < 0.05). The differences in the hazard quotient of benefit and risk balance between these two diets were not significant (p > 0.05). The average hazard quotient of iced trash fish feed culture was 0.023 ± 0.019, compared with the formulated feed culture (0.034 ± 0.028). Formulated feed and iced trash fish produce similar results as culture food for the Chinese mitten crab. In terms of cadmium exposure risk, the appropriate daily consumption of crabs is less than eight. These data can help justify culture using formulated food and the sustainable development of the Chinese mitten crab industry.

Health risks associated with sulfonamide and quinolone residues in cultured Chinese mitten crab (Eriocheir sinensis) in China.

The occurrence of 27 antibiotics (18 sulfonamides and 9 quinolones) in 92 samples of cultured Chinese mitten crab (Eriocheir sinensis) from three provinces (Anhui, Jiangsu and Liaoning) was investigated. These 21 antibiotics were detected at least once in crabs from these provinces with detection frequencies of 3.70-90.91%. Sulfonamides were detected in 53.7% of the samples at concentrations of 0.1-10 µg/kg in Jiangsu, while quinolones were detected with 90.9% of samples containing concentrations of 1-100 µg/kg in Liaoning province. Enroflxacin, ciprofloxacin, sulfaquinoxaline, sulfameter, sulfadoxine, and sulfamethoxazole were the mainly used antibiotics and enroflxacin were present at a high concentration (>100 µg/kg). Dietary assessments showed that residual antibiotics in crabs from China were far below the maximum residue limit (MRL) of total sulfonamides and quinolones, and there was almost no risk associated with crab consumption. These results will provide meaningful indications for the safety of crab consumption.

Metagenomics analysis reveals the distribution and communication of antibiotic resistance genes within two different red swamp crayfish Procambarus clarkii cultivation ecosystems.

Antibiotic resistance genes (ARGs) are emerging contaminants that pose a potential risk to human health worldwide. In this study, a metagenomic analysis was performed to investigate the distribution of ARGs in paddy field ecosystems, crayfish monoculture pond ecosystems, and rice-crayfish cultivation field ecosystems. The results showed that MacB and BcrA are two dominant ARGs, and macrolide is the dominant antibiotic not only in the water, but also in the sediment and gut of crayfish, in both the crayfish monoculture and the rice-crayfish cultivation ecosystems. Meanwhile, some lower-abundance ARGs in the water and sediment of crayfish cultivation ecosystems were significantly different in their abundance than those in rice paddy fields, and the ARGs in crayfish culture system and rice paddy fields showed even higher dissimilarities of diversity. Comprehensive analysis with redundancy analysis（RDA）and the distribution of dominant ARGs showed that the dissimilarity was related to the higher concentrations of total nitrogen (TN), total phosphorus (TP), chlorophyll a (Chla), permanganate index (CODMn), and nitrate in the water of rice paddy fields, and was related to the higher contents of N, P, K, and organic matter (OM) in the sediment of rice paddy fields. The source trackers of ARGs within the crayfish cultivation ponds and the rice-crayfish cultivation fields showed that the sediment in crayfish cultivation ponds mainly played the role of the 'sink' for ARGs, and the water and gut of crayfish mutually contributed to the high rates of ARGs. The ARG contribution rates of crayfish gut and sediment decreased and increased, respectively, in rice-crayfish cultivation fields and in crayfish monoculture ponds, which might be related to the lower crayfish biomass and the lower water depth in rice-crayfish cultivation fields.

Metagenomics Analysis Reveals Compositional and Functional Differences in the Gut Microbiota of Red Swamp Crayfish, Procambarus clarkii, Grown on Two Different Culture Environments.

The structure and function of intestinal microorganisms are closely related to host metabolism, development, physiology, and health. The red swamp crayfish, Procambarus clarkii, is an important farmed aquatic species in China, which is grown in aquaculture ponds and rice paddy fields. Since these are two distinct cultivation environments with important differences in nutrient input and ecological community composition, we hypothesized that they may have different effects on the gut microbiota of the crayfish. Here, we sought to examine this hypothesis. To that aim, metagenomics analyses were applied to unveil the taxonomic composition and functional diversity of the microbiota in the intestines of red swamp crayfish grown in aquaculture ponds and rice-crayfish cultivation environments. The results showed that Firmicutes and Proteobacteria were the two most abundant microbial components. In addition, the relative abundance of bacterial and archaeal communities, but not that of fungal and viral communities, significantly differed between the two environments. The abundance of genes involved in pathways related to genetic information processing and human diseases was lower in the guts of red swamp crayfish grown in rice-crayfish cultivation environments. In particular, the abundance of two gene sets, K13730 and K08303, which are related to epithelial cell invasion by Listeria monocytogenes and Helicobacter pylori, respectively, decreased in this culture environment. In addition, the samples from rice-crayfish cultivation environments tended to have lower relative abundance of glycosyltransferases (GTs), which were the most abundant carbohydrate-active enzymes in the samples from both groups, higher abundance of glycoside hydrolases, and lower abundance of GT2.

Effects of fenvalerate concentrations and its chiral isomers on bacterial community structure in the sediment environment of aquaculture ponds.

To investigate the effect of chiral pesticide fenvalerate (FV) on the micro-ecological environment of aquaculture pond sediment, we used an indoor static experiment to observe the effects of FV added at different concentrations with different chiral isomers on the changes in the sediment bacterial community. The 16S rDNA high-throughput sequencing technique was used to conduct sequencing and analysis of the bacterial community structure as well as changes in aquaculture pond sediments after 4 weeks of cultivation. The results showed that the microbial alpha diversity indices (Sobs and Shannon indices) of the treated groups were significantly lower than those of the control group after 4 weeks (P < 0.05), and the values in the high-concentration group were significantly lower than those of the low-concentration group (P < 0.05). In terms of bacterial group composition, the proportion of abundance of Proteobacteria and Acidobacteria in the treated groups were greater than in the control group after 4 weeks, while the proportion of abundance of Bacteroidetes and Verrucomicrobia were lower. In the high-concentration FV treatment group, the proportion of abundance of Bacteroidetes, Acidobacteria, Chloroflexi, Nitrospinae, unclassified_k_norank, Ignavibacteriae, and Nitrospirae were significantly different from those of the other groups (P < 0.05). Principal coordinate analysis (PCoA) and ANONISIM/Adonis analysis showed that the cis-enantiomer had a stronger effect on the bacterial community as the concentration of FV increased. In addition, the linear discriminant analysis effect size (LEfSe) and linear discriminant analysis (LDA) results revealed differences in the level of enrichment of bacterial groups caused by FV at different concentrations and isomer levels. Collectively, this study showed that FV residue has a pronounced effect on bacterial communities in sediment, which becomes more significant with increasing exposure concentration. The effects of the cis- and trans-enantiomers of FV on the sediment environment are different; the cis-enantiomer has a stronger effect on the bacterial community.

Transcriptome Analysis of Juvenile Tilapia (Oreochromis niloticus) Blood, Fed With Different Concentrations of Resveratrol.

Oreochromis niloticus (genetically improved farmed tilapia, GIFT) often bites the root of Polygonum cuspidatum when it is used as a floating bed, and resveratrol (RES) is mainly accumulated in the root of P. cuspidatum. Blood acts as a pipeline for the fish immune system. Generating blood transcriptomic resources is crucial for understanding molecular mechanisms underlying blood immune responses. In this study, we determined the effects of RES administration on blood transcriptomic response in GIFT. With increasing RES concentration, 133 (0.025 vs. 0.05 g/kg RES), 155 (0.025 vs. 0.1 g/kg RES), and 123 (0.05 vs. 0.1 g/kg RES) genes were detected as significant differentially expressed genes (DEGs). Three and ninety-five shared significant DEGs were found to be enriched among the three (except 0.1 g/kg RES) and four groups (0, 0.025, 0.05, and 0.1 g/kg RES), respectively. To determine the relationship between mitochondrial regulation and RES supplementation, the results of RNA-Seq were analyzed and nine mitochondria-related genes (ATP synthase or mitochondrial-function-related genes) were verified. The results revealed the same expression pattern: cytochrome c isoform X2 (cox2), katanin p60 ATPase-containing subunit A1 isoform X1 (katna1), plasma membrane calcium-transporting ATPase 1-like (atp2b1) and GTP-binding protein A-like (gtpbpal) showed the highest expression in the 0.1 g/kg RES group, while NADH dehydrogenase [ubiquinone] iron-sulfur protein 2 mitochondrial (nad7), ATP synthase subunit beta, mitochondrial (atpb), ATP synthase subunit alpha, mitochondrial-like (atpal), ATP synthase subunit alpha, mitochondrial (atpa) and ATP-dependent Clp protease proteolytic subunit, mitochondrial (clpp) revealed a dose-dependent expression following RES supplementation. Blood Ca2+-ATPase activity, and malondialdehyde, glutathione, and ATP content were significantly increased in the 0.05 (except Ca2+-ATPase activity), 0.1 g/kg RES group when compared with the controls. Eighty-nine shared DGEs were mainly enriched in antigen processing and presentation, cell adhesion molecules and phagosome pathways, based on the comparison between previous reported hepatic and the present blood transcriptome. Our study demonstrated that RES supplementation might improve the resistance to metabolism dysfunction via mitochondrial energy synthesis and/or the respiratory chain (e.g., ATPase).