Shrimp Intestine Research Articles

The cellular community in the intestine of the shrimp <i>Penaeus penicillatus</i> and its culture environments

In the present study, bacterial community diversities were investigated in the shrimp intestines, outside seawater and culture-associated environments using clone library analysis. Comparative analyses revealed that the bacterial community in the intestinal contents was most similar to that of the sediment. Bacteria in the phyla Proteobacteria and Firmicutes constituted the dominant components of the intestinal bacteria in the shrimp. The potential pathogens and probiotics were dominant members of the intestine in healthy or diseased shrimp. Intestinal bacterial communities in the healthy shrimp were composed of Bacillales, Rhodobacterales, Vibrionales, and Alteromonadales, whereas fewer bacterial groups were observed in the intestines of diseased shrimp, which were dominated by Vibrionales and Bacillales. Phylogenetic analysis revealed that nearly half of the sequences in the intestines of diseased shrimp were closely related to the potential pathogen Photobacterium damselae and Vibrio harveyi. Obvious differences in microbial diversity were also observed between outside seawater and culture-associated environments. Eukaryotes in the outside seawater were dominated by Skeletonema, Cyclotella, Thalassiosira, Guinardia, and Chaetoceros. The pond water showed less diversity in the eukaryotic community and was dominated by Skeletonema, Thalassiosira, Chaetoceros, and Oithona. The implications of the present study may be significant in the management of shrimp cultivation, as well as the detection of potential pathogens and the application of probiotics.

Characterization of bacterial community in intestinal and rearing water of Penaeus monodon differing growth performances in outdoor and indoor ponds

Penaeus monodon provides a high-quality protein source for humanity, and pond cultured shrimp often presents asynchronous growth. Microbial communities are important for the digestion and immunity of shrimp. Therefore, in this study, we investigated the bacterial characteristics of the intestine and rearing water of asynchronously growing P. monodon that were cultured in outdoor and indoor pond respectively. The results showed that the bacterial community of the rearing water was more complex than that of the intestine; the fast-growing shrimp in the indoor pond had higher intestinal bacterial diversity. Besides, the dominant bacterial composition of the water was more complex than that of the intestinal. Specifically, the abundance of Proteobacteria in the intestine was consistent with the growth performance of shrimp in the outdoor pond, which was exactly the opposite in the indoor pond. At the genus level, two cyanobacteria, Limnothrix and Cyanobium PCC-6307, were dominant in the indoor and outdoor water respectively. In the outdoor pond, Bacillus was dominant in the slow-growing shrimp intestines, while Vibrio was dominant in the fast-growing shrimp. The intestinal microbes of the fast-growing shrimp had higher proteasome metabolic capacity. These results can provide new insights into microbiome characteristics involved in the asynchronous growth of shrimp.

Isolation of Enterococcus faecium with Feeding Attractant Function from Pacific White Shrimp (Litopenaeus vannamei) Intestine

In the present study, we isolated the lactic acid bacterium strain SC-01 from Pacific white shrimp (Litopenaeus vannamei) intestine. Using conventional and molecular methods, we identified the bacterium as Enterococcus faecium, and found it had the function of feeding attractant and could inhibit the development of Vibrioparahaemolyticus (zone of inhibition: 14mm). The attractant effect of its fermentation broth is significantly better than that of the chemical attractant trimethylamine oxide (TMAO) (P <0.05), and is equivalent to that of dimethyl-beta-propiothetin (DMPT) based on the feeding behavior of shrimp. High performance liquid chromatography (HPLC) analysis suggested that inosine-5’-monophosphate (IMP) may be a component of the attractant. A biosecurity evaluation revealed a negative result in hemolytic assays, and no shrimp mortality was resulted from SC-01 fermentation broth challenge. Feeding trials (60 days) indicated that the SC-01 fermentation broth (viable counts: 5.7×109 cfumL−1) could improve feed intake, weight gain rate (WGR) and specific growth rate (SGR), and decrease the count of Vibrio sp. in the intestine of shrimp.

Changes of water, sediment, and intestinal bacterial communities in Penaeus japonicus cultivation and their impacts on shrimp physiological health

More and more studies have revealed a close relationship between gut microbial community and human health. However, the mechanism why changes in gut microflora structures affect shrimp health status remains unclear. In this study, we compared the differences of bacterial communities among intestine, water, and sediment collected from mariculture ponds of Penaeus japonicus in the early (30 days) and late (90 days) stage. Simultaneously, the relationship between bacterial communities and water quality indexes as well as shrimp physiological indexes was analyzed, respectively. The results showed that relative abundances of intestinal dominant phyla changed along with rearing times. And according to non-metric multidimensional scaling (NMDS), bacterial communities of shrimp gut had a closer relationship with the water library. By analyzing the relationship between water quality indexes and shrimp pond flora, it was shown that total nitrogen and ammonia nitrogen contents probably had the biggest impacts on bacterial communities of water, so did temperature and chemical oxygen demand on microbial communities of sediments and shrimp intestines. By analyzing the relationship between the dominant genus and physiological health indicators of shrimp, it was found that unidentified_Mitochondria, Photobacterium, and Acinetobacter were more closely associated with shrimp physiological health indicators such as total antioxidant capacity, superoxide dismutase activity, antibacterial activity, lysozyme activity, and agglutinating activity. Overall, these results suggested that intestinal microbiota of Penaeus japonicus has certain connections to ambient microflorae, environmental factors, and shrimp health status. These findings may be conducive to disease prevention and control by regulating gut and ambient microflorae in shrimp farming.

Effects of the glutathione administration via dietary on intestinal microbiota of white shrimp, Penaeus vannamei, under cyclic hypoxia conditions

Environmental stress can impair the survival, growth performance, and intestinal environment of shrimp. The objective of this study was to investigate the effect of glutathione (GSH) on the survival, growth performance, intestinal oxidation, microbiota, and histology of shrimp under hypoxia. Four treatments were used: (1) normoxia, (2) cyclic serious/medium hypoxia (CSMH), (3) CSMH and 75 mg kg−1 GSH, and (4) CSMH and 150 mg kg−1 GSH. White shrimp (Penaeus vannamei) in groups 3 and 4 were fed a commercial diet supplemented with 75 and 150 mg kg−1 GSH for a 28 day period, respectively, and they were cultured under CSMH (0.8 – 3.5 mg L−1 dissolved oxygen) for the last 14 days of the experiment. P. vannamei supplemented with 75 mg kg−1 GSH showed significantly improved survival and growth performance under CSMH compared with the CSMH condition alone. The dose of 75 mg kg−1 GSH completely eliminated overproduction of reactive oxygen species and malondialdehyde to suppress serious histopathological lesions and improve bacterial diversity and the relative abundance of beneficial bacteria, such as Rhodobacteraceae, thereby preventing pathogen (e.g., Vibrio) invasion in the intestine of shrimp under CSMH. However, the dose of 150 mg kg−1 GSH was excessive, as it led to serious impairment of survival and growth. These results indicate that 75 mg kg−1 GSH has the potential to control shrimp mortality and growth inhibition under CSMH in the shrimp farm setting.

A new insight into the intestine of Pacific white shrimp: Regulation of intestinal homeostasis and regeneration in Litopenaeus vannamei during temperature fluctuation

Litopenaeus vannamei (L. vannamei) is an essential aquaculture shrimp throughout the world, but its aquaculture industry is threatened by temperature fluctuation. In this study, our histological results indicated that the shrimp intestine has a self-repairing ability during temperature fluctuation; however the potential mechanisms were still unknown. Therefore, transcriptome profiles of the intestine were collected from shrimp at 28 °C (C28), 13 °C (T13) and 28 °C after their temperature rose back (R28) and were analyzed. A total of 2229 differentially expressed genes (DEGs) (986 up- and 1243 downregulated) were identified in the C28 group, and 1790 DEGs (933 up- and 857 downregulated) were identified in the R28 group when compared to their expression levels in the T13 group. According to the functional annotation using KEGG, we found that the immune system was the most enriched section of organismal systems and that the shrimp can mobilize the body's immune response to regulate organism homeostasis during temperature fluctuation, although cold stress decreased the immunity. Additionally, metabolic inhibition is a strategy to cope with cold stress, and the regulation of lipid metabolism was especially important for shrimp during temperature fluctuation. Remarkably, the Hippo signaling pathway might help the repair of intestinal structure. Our research provides the first histological analysis and transcriptome profiling for the L. vannamei intestine during the temperature fluctuation stage. These results enrich our understanding of the mechanism of intestinal self-repair and homeostasis and could provide guidance for shrimp farming.

Effects of dietary yeast culture on shrimp growth, immune response, intestinal health and disease resistance against Vibrio harveyi

The current study was conducted to evaluate the effects of different levels of yeast culture (YC) supplementation at 0% (YC 0%), 1% (YC 1%), and 2% (YC 2%) on growth, feed conversion ratio, body composition, intestinal morphology, microflora, immune response, and resistance to Vibrio harveyi infection in Litopenaeus vannamei. After 8-weeks feeding trial, the results showed significant improvement (p < .05) in the final weight, weight gain rate, specific growth rate, survival rate and low feed conversion ratio in YC groups than the control. Serum total protein, superoxide dismutase, catalase, alkaline phosphatase, acid phosphatase, lysozyme, and phenol oxidase in shrimps fed diet YC (2%) were significantly higher (p < .05), whereas significantly decreased trend in serum cholesterol, triglyceride, aspartate aminotransferase, and alanine aminotransferase (p < .05) were observed in YC (2%) diet. Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes were the core phylum bacteria found in the shrimp intestines. At the genus level, opportunistic pathogenic bacteria, Vibrio was significantly decreased (p < .05) while beneficial bacteria Pseudoalteromonas was increased in YC (2%) group. Intestinal villus height and width in shrimps fed YC diets were significantly improved than the control diet (p < .05). YC groups challenged test significantly showed (p < .05) improved shrimps immune response against V. harveyi infections with YC (2%) recording the highest percentage survival rate (70%). The present study demonstrated that supplementing YC (2%) can improve growth, intestinal microbiota, intestinal morphology, and immune response against V. harveyi infections in L. vannamei.

Effects of carbon source addition on microbial community and water quality in recirculating aquaculture systems for Litopenaeus vannamei

In order to study the effects of carbon source addition on the bacterial community, water quality and shrimp growth in the recirculating aquaculture system of Litopenaeus vannamei, sucrose with 50% of the daily feed was added daily to the system from the middle stage of culture. The bacterial communities in biofilters, aquaculture waters and shrimp intestines were measured using an Illumina MiSeq platform. The addition of sucrose did not significantly improve the regulation of nitrogen in the water, although there was a tendency to increase shrimp production. The addition of sucrose also had little effect on the bacterial community of water and intestine, but had significant effects on the bacterial community in the biofilter. Carbon addition transformed the dominant bacterial taxa of the biofilter from the Proteobacteria dominated by Rhodobacteraceae to the Planctomycetes dominated by Planctomycetaceae. In this study, the characteristics of the bacterial community and the effects of carbon source addition in the recirculating aquaculture system of L. vannamei are presented, which provides a basis for microbial management in the recirculating aquaculture system of L. vannamei. In view of the unknown role of numerous bacterial groups, the function of the bacterial community needs further study.

Bioprospecting of an Indigeneous Bacillus thuringiensis Strain G5-8-3T02 for Shrimp Culture System

Aim: An indigenous Bacillus thuringiensis strain G5-8-3T02 earlier isolated from healthy shrimp intestine and established to safeguard Penaeus monodon from Vibrio mimicus infection was assessed as a potential candidate bacterium for drug enhancement for shrimp culture systems.&#x0D; Methodology: Optimal temperature, pH and salinity for growth and antibacterial activity of Bacillus thuringiensis against Vibrio mimicus were determined. The effects of enzymes (pepsin, catalase, lipase and α- amylase), pH (2-9), heat (37°C – 121°C) and surfactants (Sodium dodecyl sulphate and Tween 80) on antibacterial activity were also evaluated. Cell growth and antibacterial activity were monitored daily for 5 days via spectrophotometric method at 600 nm and agar well diffusion assay respectively. The metabolite extracted with methanol was analyzed for bioactive compounds using Gas Chromatography-Mass Spectrometry (GC-MS).&#x0D; Results: The optimum temperature, pH and salinity for growth and metabolite production were 35°C, pH 6-7 and 10-15 ppt. respectively. The crude extract did not totally lose its activity when treated with enzymes, various pH values, heat and surfactants. The quantitative composition of the metabolite revealed 15 bioactive compounds. The main compound produced was 2, 6, 10-Trimethyltridecane with peak area of 14.58%.&#x0D; Conclusion: The non-pathogenic, antagonistic, indigenous Bacillus thuringiensis strain G5-8-3T02 could be engaged in the management of vibriosis in shrimp culture since the use of antibiotics in aquaculture for disease control yields objectionable effects. The identified bioactive compounds might be valuable for drug development for shrimp culture system.

Changes on the intestinal bacterial community of white shrimp Penaeus vannamei fed with green seaweeds

In recent years, development of sustainable and ecological food production has gained worldwide interest. It seems clear that this phenomenon is causing changes in aquaculture-focused research, with the development of new integration systems. However, it is still necessary to understand different aspects involved in integrated systems, including co-culture systems such as shrimp and seaweed. This study evaluated the effect of green seaweeds as food source on white shrimp Penaeus vannamei intestinal bacterial communities. Shrimp were evaluated after a 4-week experimental trial under different diet treatments: fed with only pellet (P), only Ulva clathrata (UC), U. clathrata + pellet (UCP), only Ulva lactuca (UL), and U. lactuca + pellet (ULP). In terms of growth and survival, no significant differences (P > 0.05) were found between ULP and UCP treatments compared with the control (P). Analysis of the bacterial biota of shrimp intestine revealed significant differences on community composition in ULP, UL, and UC compared with the control (P) (P < 0.05). We found that Proteobacteria is the most abundant phylum in all treatments, followed by Bacteroidetes for UC, UCP, and UL and Actinobacteria for P and ULP treatments. Shrimp fed only with seaweed U. lactuca (UL, ULP) had a significantly higher abundance of Rubritalea, Lysinibacillus, Acinetobacter, and Blastopirellula, and for U. clathrata treatments (UC, UCP), it was Litoreibacter. Relative abundance of Vibrio was higher in the control (P), showing a decrease in UC and UL treatments. Our findings provide a better understanding of integrated aquaculture systems, specifically those utilizing seaweed as natural feed source.

Suppression of white feces syndrome in Pacific white shrimp, Litopenaeus vannamei, using hen egg white lysozyme

White feces syndrome (WFS) is one of the major constrains for shrimp cultivation. Although the pathogen causing WFS remains largely unknown, WFS has been associated with an increase in vibrio abundances in shrimp haemolymph and intestine. We demonstrated that hen egg white lysozyme (HEWL) inhibited in vitro growth of Vibrio spp. including V. alginolyticus, V. harveyi, and V. parahaemolyticus. To alleviate shrimp losses from WFS, HEWL was supplemented into feed at 0.005, 0.025, 0.125, and 0.625 g/kg diet. Supplementation at 0.125 (HEWL0.125) and 0.625 (HEWL0.625) g/kg diet retained the antimicrobial activity under the cultivation water. Both of the supplemental levels also showed a significant antimicrobial activity and reduction in vibrio richness in shrimp gastrointestinal tract. We further analyzed the effect of HEWL supplementation on the expression of immune and antioxidant related genes in hepatopancreas. HEWL0.125 substantially upregulated the expression of prophenoloxidase, serine proteinase, superoxide dismutase, thioredoxin, and ferritin. Growth performance analysis of weight gain, average daily gain (ADG), feed conversion ratio, and survival rate was also determined, but there were no differences in those parameters. When shrimp were challenged with a pathogenic strain of V. harveyi, we observed the greater survival rate in HEWL0.125 than that of the control group (66.67% vs. 16.67%). Importantly, the effect of HEWL0.125 on WFS was evaluated in a shrimp farm. The incidence of WFS was disappeared without recurrence in shrimp fed HEWL0.125. As a result, the survival and ADG were improved significantly. In conclusion, dietary supplementation of HEWL0.125 could inhibit vibrio growth and stimulate immune- and antioxidant-related gene expression leading to resistance against WFS in shrimp.

Digestive microbiota of shrimp Penaeus vannamei and oyster Crassostrea gigas co-cultured in integrated multi-trophic aquaculture system

A current practice of marine aquaculture is to integrate different trophic-level organisms to optimise nutrients uptake, improve water quality, and potentially increase economic income. Even though bacterial communities in the intestine of the Pacific white shrimp Penaeus vannamei and in the digestive gland of the Pacific oyster Crassostrea gigas have been studied, the effect of an integrated multi-trophic aquaculture (IMTA) system in the digestive microbiome of both species is unknown. In the present work, we examined the bacterial communities in the intestine of P. vannamei and digestive gland of C. gigas under monoculture and co-culture in IMTA conditions. The results revealed a higher final weight of shrimp in co-culture compared to monoculture (2.73 ± 0.07 g and 2.47 ± 0.13 g, respectively) (P < .1). The total sedimentable particles in water were significantly reduced in co-culture conditions compared to shrimp monoculture (P < .05). Analysis of oyster gut bacterial communities in co-culture with shrimp showed higher diversity compared to oyster from monoculture and shrimp treatments. We found that Proteobacteria is the most abundant phylum in all treatments, followed by Bacteroidetes and Actinobacteria. Higher abundance of Bacteroidetes and abundance variation in Alphaproteobacteria (Sphingomonodales and Rhodobacterales) of oyster from IMTA were attributed to consumption of shrimp waste and consequently reduction of suspended matter in the system. Moreover, shrimp intestine and oyster digestive gland in the co-culture system showed a lower relative abundance of Vibrionaceae compared to monoculture treatments. These results suggest that IMTA system impose digestive microbiome dynamics changes that could improve water management and shrimp productivity.

The effects of water additive Bacillus cereus and Pediococcus acidilactici on water quality, growth performances, economic benefits, immunohematology and bacterial flora of whiteleg shrimp (Penaeus vannamei Boone, 1931) reared in earthen ponds

This study was aimed to investigate the effects of two probiotics, Bacillus cereus and Pediococcus acidilactici, on the water quality, growth performance, the survival ratio, economic benefits, immunohematology and bacterial flora in the intestine of whiteleg shrimp, Litopenaeus vannamei after 110 days. Nine earthen ponds (each one 1.2 hectare) were adjusted as three treatments including control (without adding bacteria), containing P. acidilactici probiotic (106 CFU/mL) and containing B. cereus probiotic (106 CFU/mL). The results showed that the adding B. cereus and P. acidilactici to the water pond positively decreased nitrate, ammonia and biochemical oxygen demand when compared with the control group (p < .05). Regarding growth performance, treating shrimp with B. cereus caused significantly higher weight gain (16.72 g) and survival ratio (94.50%) in comparison with control group (p < .05). Using these probiotics could increase shrimp production (27.30%, 18.42%) and net income (92.94%, 49.20%) as well. Respect to immunity, total hemocyte count (9.00), total protein (8.92 g/dl) and lysozyme activity (21.55 U/ml) in treated whiteleg shrimp with B. cereus were significantly higher than those untreated (p < .05). In conclusion, adding B. cereus (106 CFU/ml) to the earthen pond can be suggested in shrimp farm.

Mitochondrial ATPase inhibitor factor 1, MjATPIF1, is beneficial for WSSV replication in kuruma shrimp (Marsupenaeus japonicus)

ATPase Inhibitory Factor 1 (IF1) is a mitochondrial protein that functions as a physiological inhibitor of F1F0-ATP synthase. In the present study, a mitochondrial ATPase inhibitor factor 1 (MjATPIF1) was identified from kuruma shrimp (Marsupenaeus japonicus), which was demonstrated to participate in the viral immune reaction of white spot syndrome virus (WSSV). MjATPIF1 contained a mitochondrial ATPase inhibitor (IATP) domain, and was widely distributed in hemocytes, heart, hepatopancreas, gills, stomach, and intestine of shrimp. MjATPIF1 transcription was upregulated in hemocytes and intestines by WSSV. WSSV replication decreased after MjATPIF1 knockdown by RNA interference and increased following recombinant MjATPIF1 protein injection. Further study found that MjATPIF1 promoted the production of superoxide and activated the transcription factor nuclear factor kappa B (NF-κB, Dorsal) to induce the transcription of WSSV RNAs. These results demonstrate that MjATPIF1 benefits WSSV replication in kuruma shrimp by inducing superoxide production and NF-κB activation.

Screening of bacterial strains from the gut of Pacific White Shrimp (Litopenaeus vannamei) and their efficiencies in improving the fermentation of soybean meal.

Microbial fermentation is an efficient, economical and eco-friendly approach to overcome the limitations in soybean meal replacement of fish meal in aquaculture. However, little research focused on the development of shrimp-derived strains for fermentation of SBM. In this study, Bacillus sanfensis (SQVG18) and Bacillus stratosphericus (SQVG22) were screened from shrimp intestine for fermentation according to the activities of protease, cellulase and phytase. The optimized fermentation conditions of SQVG18 and SQVG22 were as follow: fermentation temperature (40°C vs 35°C), fermentation time (48hboth), inoculation amount [4% both (v/m)], solid-liquid ratio [1:1.2vs 1:1 (g/ml)]. After 48 hfermentation, SQVG18 and SQVG22 increased crude protein content by 6.93% and 5.95%, respectively; degraded most of macromolecular proteins to micromolecular proteins (< 20kDa); improved amino acids profiles, like lysine and methionine in particular; significantly decreased the anti-nutritional factors such as trypsin inhibitor, glycinin and β-conglycinin (P<0.05). In addition, both strains were observed no hemolytic activity, less antibiotic resistance genes and definite inhibition to common shrimp pathogens of Vibrio alginolyticus sp. and Vibrio parahaemolyticus sp. These results indicated that both strains could improve nutrition values of soybean meal effectively and have potential applications in shrimp culture.

Response of intestine microbiota, digestion, and immunity in Pacific white shrimp Litopenaeus vannamei to dietary succinate

Succinate (SA) is the precursor of propionate that influence the intestine physiological function of animals. In this study, we investigated the microbiome, digestive, and immune responses in the intestines of Pacific white shrimp Litopenaeus vannamei fed diets containing different levels of SA: 0 g/kg (Control), 2.5 g/kg (SA1), 5.0 g/kg (SA2), and 10.0 g/kg (SA3) for 56 days. The results showed that dietary SA improved the intestine mucosa morphology, increased the short-chain fatty acids contents, and altered the intestine microbiota composition. Specifically, SA increased the abundances of Proteobacteria and decreased the abundance of Bacteroidetes. The beneficial bacteria including Ruegeria, Lutimonas, Mameliella, and Sphingomonas were enriched in response to dietary SA; these genus might be involved in nutrient metabolism and the degradation of toxic compounds and pollutants. Additionally, dietary SA also improved the activity of digestive enzymes (amylase, lipase, trypsin, and pepsin) and immune enzymes (total antioxidant capacity, phenoloxidase, total nitric oxide synthase, and nitric oxide), and the expression of immune-related genes (prophenoloxidase, anti-lipopolysaccharide factor, lysozyme, heat shock protein 70, thioredoxin, mucin-1, mucin-2, mucin-5 AC, mucin-5B, and mucin-19) in the intestine of the shrimp. These results revealed that dietary SA had a positive effect on the intestine health of L. vannamei by modulating the microbial composition and SCFA contents, and enhancing the digestive and immune response in the shrimp intestine.

Effects of replacing fishmeal with dietary soybean protein concentrate (SPC) on growth, serum biochemical indices, and antioxidative functions for juvenile shrimp Litopenaeus vannamei

This experiment was conducted to assess the possibility of replacing fishmeal (FM) with Soybean Protein Concentrate (SPC) at different levels (Diet 1 (0%), Diet 2 (3.08%), Diet 3 (6.16%), Diet 4 (9.24%), Diet 5 (12.32%), Diet 6 (15.40%), Diet 7 (18.48%)) as well as its effects on growth, serum biochemical indices and antioxidant activities, body composition, histology, intestinal flora and disease resistance in Litopaeneaus vannamei. There were three replicates in each group in the experiment (Initial mean weight = 0.23 ± 0.00 g) and were fed their respective diets for 8 weeks. Growth performance in Diet 6 compared to the Diet 1, significantly increased (P < 0.05) and the survival rate ranged from 90% to 95%. No significant difference was observed among the groups in terms of crude protein, moisture, and ash content. There was an increase in serum acid phosphatase, alkaline phosphatase, High-Density Lipoprotein Cholesterol, Total Antioxidant capacity, Glutathione peroxidase. Significant decreases (P < 0.05) in Glucose and Total Cholesterol were observed in the shrimp. Also, no significant difference was observed in serum Alanine Aminotransferase, and Total protein (P ˃ 0.05). Histology of the intestine showed Villus height and intestinal wall thickness significantly increased (P < 0.05) with increasing inclusion of SPC, 15.40% had the highest value. In intestinal flora, replacement of FM with SPC in the shrimp intestine had positive effects on a number of beneficial bacteria such as Pseudoalteromonadaceae among the treatment groups with 15.40% having the highest value as compared to 0% at the family level. Furthermore, diversity indices and richness estimate increased with increasing SPC levels. Disease resistance was increased in shrimp among treatment groups, 15.40% recording the lowest mortality percentage of 40.22% after the challenge test. In conclusion, with reference to all the parameters, replacement of FM with SPC at 15.40% could be used to cater for shrimps’ dietary needs.

Intestinal microbiota of white shrimp, Litopenaeus vannamei, fed diets containing Bacillus subtilis E20‐fermented soybean meal (FSBM) or an antimicrobial peptide derived from B. subtilis E20‐FSBM

The purpose of the present study is to profile the microfloral structure in the intestines of the white shrimp, Litopenaeus vannamei, after being fed a control diet, in comparison with the diets containing Bacillus subtilis E20-fermented soybean meal (FSBM) or an antimicrobial peptide (AMP) isolated from B. subtilis E20-FSBM (diets designated FSBMD and AMPD, respectively) for 60 days. Metagenomic data showed detection of eight phyla, 20 classes, 40 orders, 68 families and 96 genera. Despite no statistically significant difference, an evaluation of microbial diversity recorded higher species richness, Shannon–Weaver diversity index and evenness in the AMPD and FSBMD groups, compared to the control diet group. Venn diagrams showed that 58 of the operational taxonomic units (OTUs) were shared among the control, FSBMD and AMPD groups, but additional beneficial microbes were only found in the FSBMD and AMPD groups. In addition to the augmentation of beneficial bacteria in the FSBMD and AMPD groups, the abundance of potential pathogens, Vibrio and Flavobacterium, was lower in the gut of shrimp fed the FSBMD and AMPD. The results clearly suggest that the FSBMD and AMPD have the capability to change the microfloral structure of shrimp intestines and could be used for disease prevention in shrimp aquaculture.

Effects of T-2 toxin on digestive enzyme activity, intestinal histopathology and growth in shrimp Litopenaeus vannamei

T-2 toxin (T-2), a naturally occurring mycotoxin that often accumulates in aquatic animals via contaminated feed, is toxic to animals, including humans. In this study, six groups of shrimp (n = 30 shrimps/group) were given T-2 in feed at concentrations of 0–12.2 mg/kg for 20 days. T-2 accumulation, intestinal histopathology, digestive enzyme activities and subsequent effects on shrimp are reported. Compared to the control, T-2 significantly reduced weight gain, specific growth rate, and survival. The histopathology of shrimp intestine showed concentration-dependent degenerative and necrotic changes in response to dietary T-2. Progressive damage to the microstructures of shrimp intestine occurred with increasing dietary T-2 concentrations, with initial inflammation of the mucosal tissue at T-2 concentrations of 0.5 and 1.2 mg/kg, progressing to disappearance of intestinal villi and degeneration and necrosis of the submucosa at 12.2 mg/kg. Intestinal amylase and protease activities increased at low T-2 concentrations but showed significant inhibition at high concentrations; however, the opposite trend occurred for lipase activity. Collectively, these results indicate that digestive enzyme activities and mucosal structures are markedly affected by exposure to T-2, and these may have contributed to the lower survival rate of shrimp.

A global view of hepatopancreas and intestinal reveals the potential influencing mechanism of aflatoxin B1 on nutrition and metabolism inLitopenaeus vannamei

The present study was to determine the time-dependent alterations in growth performance, histomorphology, digestive enzymes activities and the genes expression related to target of rapamycin (TOR) signalling pathway involved in hepatopancreas and intestine of Litopenaeus vannamei at 3, 6, 12, 18, 24 and 30 days after Aflatoxin B1 (AFB1) challenge. The results manifested that AFB1 could induce a significant decrease in growth performance and visible variations of the hepatopancreas and intestine structures in shrimp. Meanwhile, the digestive enzymes activities and genes expression level were significantly lower in the experimental group than in the control group and showed a time-dependent decrease (p < 0.05). The expression levels of tor and s6k were significantly higher in the experimental group than in the control group from days 6 to 24 and showed a tendency to increase first and then decrease as a whole (p < 0.05). Meanwhile, we analysed candidate pathways involved in hepatopancreas and intestine of shrimp in metabolic response to AFB1. The mainly disturbed pathways related to metabolism in hepatopancreas were involved in pyrimidine, glycosylphosphatidylinositol, glycosaminoglycan, vitamin and amino acid biosynthesis and metabolism, while the mainly disturbed metabolic pathways in intestine were glycosaminoglycan, vitamin and amino acid biosynthesis and metabolism.