Shrimp Intestine Research Articles

Shrimp Intestinal Microbiota Homeostasis: Dynamic Interplay Between the Microbiota and Host Immunity

ABSTRACTThe shrimp intestine harbors a microbiota that has pivotal roles for host's physiology. Imbalance of shrimp intestinal microbiota has been shown closely related to the occurrence of diseases. The morphological and biological features of the shrimp intestine are considered suboptimal for stable microbial colonization, making the intestinal microbiota composition highly susceptible to the impact of environmental changes or stressors, and particularly unstable. Therefore, the relative unsteadiness of the microbiota composition represents a continuous threat to host survival. Shrimp intestinal microbiota homeostasis is achieved through a dynamic interplay between the microbiota and the host's innate immunity. The shrimp intestine possesses effective innate immune mechanisms that can suppress the uncontrolled proliferation of microbiota components, and simultaneously protect the microbiota from elimination. The mechanism(s) by which the microbial components and the intestinal innate immunity interact with each other to achieve homeostasis represents an interesting interplay between host and microbiota. This review summarizes the current knowledge about intestinal microbiota colonization in shrimp, as well as the intricate mechanisms employed by the intestinal immune system to regulate this microbiota. Moreover, the potential intervention strategies to promote and protect shrimp intestinal homeostasis by modulating the microbiota are also discussed. Thus, this review seeks to comprehensively analyze the current information and contribute to a deeper understanding of the complex interplay between the shrimp intestinal microbiota and innate immunity in maintaining shrimp intestinal homeostasis and overall health. This enhanced understanding may potentially open new avenues for aquaculture management and disease mitigation strategies, ultimately benefiting the shrimp farming industry.

Integrating short- and full-length 16S rRNA gene sequencing to elucidate microbiome profiles in Pacific white shrimp (Litopenaeus vannamei) ponds.

Despite their immense economic value as a key aquaculture species, the production of Pacific white shrimp (Litopenaeus vannamei) faces significant challenges from intensive farming practices and disease outbreaks. Routine microbial profiling for disease surveillance could be a promising approach to anticipate and control disease outbreaks. To achieve this, accuracy in microbial profiling in shrimp ponds is crucial for enabling targeted action and prevention. Extensive documentation emphasizes that, beyond biological factors (related to the host, diet, or health status during the rearing period), technical elements, including sequencing techniques significantly influence bacterial community profiling. This study investigated the influence of short- and long-read sequencing of 16S rRNA genes on the microbial profiles in shrimp intestines, water, and sediments. The origin of the samples (intestine or environmental) in shrimp culture ponds primarily drove the observed differences in core microbial species. The ecological niches accounted for 56% of bacterial community variations in culture ponds. Both sequencing approaches showed consistent results in identifying higher-rank taxa and assessing alpha and beta diversity. However, at the species level, full-length 16S rRNA gene sequences provided better resolution than V3-V4 sequences. For routine microbial profiling in shrimp culture ponds, our study suggests that short-read sequences were sufficient for determining overall bacterial community.IMPORTANCEThis interdisciplinary study investigated the influence of sequencing techniques on bacterial communities profiling within Pacific white shrimp (Litopenaeus vannamei) ponds. By integrating aquaculture, microbiology, and environmental science, we revealed the role of ecological niches and factors like salinity and pH on microbiota diversity and composition in shrimp intestines, pond water, and sediment. Additionally, we compared the taxonomic resolution using partial versus full-length 16S rRNA gene sequences, highlighting the value of longer amplicons for precise identification of key taxa. These findings provide novel insights into microbial dynamics underlying environmental effects in shrimp aquaculture. Comprehensive characterization of the pond microbiome could lead to management strategies that promote shrimp health and productivity. Furthermore, the potential of a multi-omics approach for integrating complementary data streams to elucidate environment-microbiome-host interactions was highlighted.

Ammonia nitrogen stress induces dysbiosis of the intestinal bacterial community and facilitates the enrichment of pathogenic bacteria in intestines of shrimp

Environmental stress can disrupt the intestinal microbiota of aquatic animals, thereby impacting their health status. In this study, we aimed to elucidate the dynamic changes in the bacterial community within shrimp intestines under short-term ammonia nitrogen stress and investigate the subsequent ecological risks associated with it. Our findings revealed a significant reduction in the Chao1 diversity index within shrimp intestines of the ammonia nitrogen stress group compared to the Control group. Furthermore, distinct disparities in the bacterial community structures were observed between the two groups at 72 h and 120 h post-stress. Additionally, ammonia nitrogen stress significantly altered the abundances of specific bacterial taxa within shrimp intestines. Specifically, the abundance of Bacillus subtilis increased while that of Lactococcus garvieae decreased in the intestine under stress at 72 h. Additionally, Roseivivax jejudonensis exhibited an increase, whereas uncultured_o_Saccharimonadales and Hyphomicrobium sp. showed a decrease at 120 h. Notably, opportunistic pathogens such as Vibrio parahaemolyticus experienced a significant increase at 72 h post-stress, potentially due to a substantial contribution from stochastic processes in shaping the assembly of the intestinal community. Additionally, the intestinal bacterial community of shrimp displayed a noticeable decrease in complexity of bacterial co-association networks under stress conditions. Thus, short-term exposure to ammonia nitrogen disrupts the integrity of shrimp's intestinal community, indicating potential ecological risks within their microhabitat. Confirmatively, we conducted the immersion challenge experiment of V. parahaemolyticus on shrimp post community disturbance under stress, and observed a significantly higher copy numbers of V. parahaemolyticus in host intestines of stressed compared to control shrimp. These findings can provide novel insights into the interactions among ammonia nitrogen stress, intestinal microbiota and host health of aquatic animals, and guide the practices for shrimp healthy culture.

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.

Enhancing shrimp growth and immunity with green algal Caulerpa lentillifera polysaccharides through gut microbiota regulation

The polysaccharides from green algal Caulerpa lentillifera (CLP) have shown strong positive effects on terrestrial animal immunity. However, little is known about their function in aquatic animals. Here, we fed shrimp with diets containing different CLP contents (0, 0.1 %, 0.2 %, and 0.4 %). Our results indicated that the increase of 0.1 % CLP could significantly enhance shrimp growth rate, weight gain, and hepatopancreas index, and all doses of CLP could greatly increase the shrimp crude protein content compared to the control. In addition, 0.1 % CLP significantly enhanced the shrimp phagocytic activity, hepatopancreatic acid phosphatase (ACP) activity, hepatopancreatic alkaline phosphatase (AKP) activity, and plasma superoxide dismutase (SOD) activity, while reducing plasma malondialdehyde (MDA) activity compared to the controlled diet. The 16S rDNA sequence of shrimp intestine microbiota indicated that the intestinal microbiota diversity in shrimp fed with 0.2 % CLP diets was higher than that in the control, including an increase in beneficial microbial groups (Proteobacteria, Actinobacteria, Firmicutes, and TM7) and a decrease in harmful ones (Shewanella and Vibrio). Feeding with CLP could enrich carbohydrate and amino acid metabolism. Correlation analysis indicated that peroxidase (POD) had the widest correlation with communities, being inversely correlated with seven distinct microbial taxa. Moreover, four distinct microbial taxa were significantly associated with weight. These data indicate that CLP is a potential shrimp forage supplement and recommend the optimum dose of CLP inclusion to be 0.1 %–0.2 % in shrimp diets.

Isolation of Lactobacillus plantarum CMT1 from shrimp intestine and its effects on growth and survival of the whiteleg shrimp, Litopeneaus vannamei

Probiotics are widely applied in aquaculture, which can improve the growth, survival and health of aquatic animals. The aim of this study was to isolate and evaluate a Lactobacillus strain from the intestine of healthy whiteleg shrimp, Litopenaeus vannamei. A total of 20 Lactobacillus isolates showed rod-shaped morphology, gram-positive, non-motile, non-spore forming, and catalase and oxidase negative. Among the isolates, strain CMT1 exhibited the highest antibacterial activity against Vibrio parahaemolyticus and extracellular enzyme activity, which was selected and identified as Lactobacillus plantarum CMT1 based on 16S rDNA gene sequencing. This strain was also chosen to evaluate its effects on growth and survival of the whiteleg shrimp as a feed supplement. Four different diets were prepared, including the control (a commercial diet without L. plantarum CMT1) and three different concentrations of L. plantarum CMT1, viz. T1 (106 CFU kg diet-1), T2 (107 CFU kg diet-1), and T3 (108 CFU kg diet-1). After a 56-day feeding trial, the growth parameters in the T3 group had the highest values and showed a significant difference compared to the other groups. The survival rates of shrimp fed T2 and T3 diets were significantly higher than those in the control diet (p < 0.05). The lowest FCR value was recorded in the T3 group and showed a significant difference compared to the control group (p < 0.05). In addition, Lactobacillus counts in T2 and T3 groups increased significantly from day 28, which indicated that L. plantarum CMT1 could sustain its population in the intestine of shrimp. However, the total Vibrio sp. count in the T2 and T3 groups was significantly lower than that in the control group (p < 0.05). In conclusion, L. plantarum CMT1 could be used as a potential probiotic for shrimp aquaculture, and the recommended level of the probiotic strain CMT1 is 108 CFU kg diet-1.

Changes of bacterial communities and bile acid metabolism reveal the potential “intestine-hepatopancreas axis” in shrimp

The interaction between the gut and the liver plays a significant role in individual health and diseases. Mounting evidence supports that bile acids are important metabolites in the bidirectional communication between the gut and the liver. Most of the current studies on the “gut-liver axis” have focused on higher vertebrates, however, few was reported on lower invertebrates such as shrimp with an open circulatory system. Here, microbiomic and metabolomic analyses were conducted to investigate the bacterial composition and bile acid metabolism in intestine, hemolymph and hepatopancreas of Penaeus vannamei fed diets supplemented with octanoic acid and oleic acid. After six days of feeding, the bacterial composition in intestine, hemolymph and hepatopancreas changed at different stages, with significant increases in the relative abundance of several genera such as Pseudomonas and Rheinheimera in intestine and hepatopancreas. Notably, there was a more similar bacterial composition in intestine and hepatopancreas at the genus level, which indicated the close communication between shrimp intestine and hepatopancreas. Meanwhile, higher content of some bile acids such as lithocholic acid (LCA) and α-muricholic acid (α-MCA) in intestine and lower content of some bile acids such as taurohyocholic acids (THCA) and isolithocholic acid (IsoLCA) in hepatopancreas were detected. Furthermore, Spearman correlation analysis revealed a significant correlation between bacterial composition and bile acid metabolism in intestine and hepatopancreas. The microbial source tracking analysis showed that there was a high proportion of intestine and hepatopancreas bacterial community as the source of each other. Collectively, these results showed a strong crosstalk between shrimp intestine and hepatopancreas, which suggests a unique potential “intestine-hepatopancreas axis” in lower invertebrate shrimp with an open circulatory system. Our finding contributed to the understanding of the interplay between shrimp intestine and hepatopancreas in the view of microecology and provided new ideas for shrimp farming and disease control.

Dietary Bacillus velezensis T23 fermented products supplementation improves growth, hepatopancreas and intestine health of Litopenaeus vannamei

This study aimed to elucidate the effects of dietary fermented products of Bacillus velezensis T23 on the growth, immune response and gut microbiota in Pacific white shrimp (Litopenaeus vannamei). Shrimp were fed with diets containing fermentation products of B. velezensis T23 at levels of (0, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 g/kg) for 4 weeks, to assess the influence on shrimp growth. The results showed that 0.3 and 0.4 g/kg T23 supplementation improved shrimp growth and feed utilization. Based on these results we selected these three diets (Control, 0.3T23 and 0.4T23) to assess the effect on immune response and gut microbiota of shrimp. Compared with the control, the 0.3T23 and 0.4T23 groups enhanced lipase and α-amylase activities in the gut significantly. Moreover, the 0.4T23 group decreased TAG and MDA levels in hepatopancreas, ALT and AST levels of serum significantly (P < 0.05). In hepatopancreas, CAT and SOD activities were improved observably and the MDA content was reduced markedly in both T23 groups. The expressions of antimicrobial related genes, Cru and peroxinectin in the 0.3T23 group, and proPO and peroxinectin in the 0.4T23 group were up-regulated remarkably (P < 0.05). Moreover, hepatopancreas of shrimp fed with a diet amended with T23 showed a significant down-regulated expression of nf-kb and tnf-α genes, while expressions of tgf-β was considerably up-regulated. Furthermore, serum LPS and LBP contents were reduced markedly in T23 groups. Intestinal SOD and CAT were noteworthy higher in T23 groups (P < 0.05). In the intestine of shrimp fed on the diet enriched with T23 the expression of nf-κb and tnf-α exhibited markedly down-regulated, whereas hif1α was up-regulated (P < 0.05). Besides, in the intestine of shrimp grouped under T23, Cru and peroxinectin genes were markedly up-regulated (P < 0.05). Dietary 0.3 g/kg T23 also upregulated the ratio of Rhodobacteraceae to Vibrionaceae in the gut of the shrimp. Taken together, the inclusion of B. velezensis T23 in the diet of shrimp enhanced the growth and feed utilization, enhanced hepatopancreas and intestine health.

The impacts of low fishmeal diet to the antioxidant capacity, endoplasmic reticulum stress, apoptosis and intestinal health of Litopenaeus vannamei as the went on of the feeding trial

Plant protein sources are the main alternative to fish meal (FM), but excessive substitution can induce inflammatory responses and oxidative stress in aquatic animals. In this study, the antioxidant capacity, endoplasmic reticulum stress (ERS), apoptosis and intestinal health of Litopenaeus vannamei at the different stages of feeding trial were evaluated after replacing FM with soy protein concentrate (SPC). Two diets were designed: HF diet (25% FM) and LF diet (15% FM + 10% soy protein concentrate), respectively. The samples were collected at 7d, 14d, 28d, 42d, 56d of the feeding trial. The results showed that the antioxidant capacity of the hepatopancreas of shrimp fed the LF diet gradually decreased after 28d. The glutathione peroxidase (GSH-PX) activity, superoxide dismutase (T-SOD) activity and total antioxidant capacity (T-AOC) showed a decreasing trend with the went on of the feeding trial and were lower than those of shrimp fed a HF diet. The length of microvilli and height of mucosal folds in shrimp fed the LF diet were significantly lower than those fed the HF diet after 42d (P<0.05), and the endoplasmic reticulum and mitochondria were swollen, and the mitochondrial matrix showed irregular structure and even almost complete dissolution at 56d. The expression of hepatopancreatic endoplasmic reticulum stress (ERS)-related genes was highest at 14d, and the hepatopancreatic endoplasmic reticulum-related genes were overall higher in shrimp fed the LF diet than those fed the HF diet after 28d. The expression of apoptosis-associated genes in hepatopancreatic cells showed an overall decreasing trend. However, the relative expression of intestinal ERS and apoptosis related gene was in the opposite trend. ERS was enhanced and apoptosis was inhibited in shrimp since 7d of the feeding trial when the dietary FM level was reduced. In conclusion, the antioxidant capacity and immune response of shrimp would be reduced as the feeding trial went on, ERS and apoptosis in the intestine of shrimp fed a LF diet would be earlier to be induced compared to those fed the HF diet.

Nitrite nitrogen stress disrupts the intestine bacterial community by altering host-community interactions in shrimp

Environmental stress can disrupt the intricate interactions between the host and intestine microbiota, thereby impacting the host health. In this study, we aimed to elucidate the dynamic changes in the bacterial community within shrimp intestines under nitrite nitrogen (nitrite-N) stress and investigate potential host-related factors influencing these changes. Our results revealed a significant reduction in community diversity within the intestine exposed to nitrite-N compared to control conditions. Furthermore, distinct differences in community structures were observed between these two groups at 72 h and 120 h post-stress induction. Nitrite-N stress also altered the abundances of some bacterial species in the intestine dramatically. It is noteworthy that, in comparison to the 72 h, intestine bacterial community structure of stressed shrimp exhibited a significantly higher degree of dispersion after 120 h of nitrite-N stress when compared to control shrimp, and the relative abundance of numerous bacterial species experienced a substantial decrease or even reached 0 %. Moreover, it led to a reduction in bacterial community interactions and decreased competitiveness within the intestine microbiota. Notably, the influence of bacterial community assemblies in the shrimp intestine shifted from a stochastic process to a deterministic one after 24 h and 72 h of nitrite-N stress, returning to a stochastic process at 120 h. We further observed a close association between this phenomenon and host's response to nitrite-N stress. Expression levels of differentially expressed genes in the intestinal tissue significantly impact the intestine bacterial diversity and abundance of species. In particular, the significant decline in bacterial diversity and abundances of quite a few species in intestine was attributed to the up-regulation of peritrophin-48-like. Overall, nitrite-N stress indeed disrupted the intestine microbiota and changed the host-microbiota interactions of shrimp. This study offered novel insights into environment-host-microbiota interactions and also provided practical guidance for promoting healthy shrimp cultivation practices.

Biochemical, histological and transcriptional response of intestines in Litopenaeus vannamei under chronic zinc exposure

Zinc (Zn) is an essential trace element for the normal physiological function of aquatic organisms, but it could become toxic to organisms when the concentration increased in water. As the first line of defense, the shrimp intestines are the most susceptible organ to environmental stress. In this study, the chronic toxicity of 0 (control, IC), 0.01(IL), 0.1(IM) and 1mg/L (IH) Zn in intestines of Litopenaeus vannamei was investigated from the perspectives of biochemical, histological and transcriptional changes after exposure for 30 days. The results showed that the intestinal tissue basement membrane is swollen in the IM and IH groups and detached in the IH group. The total antioxidant capacities (T-AOC) were reduced while the content of malondialdehyde (MDA) were increased significantly in IM and IH groups. The production of reactive oxygen species (ROS) was increased significantly in IH group. Many differentially expressed genes (DEGs) were identified in IL, IM and IH groups, respectively. GO and KEGG enrichment analyses were conducted on the DEGs to obtain the underlying biological processes and pathways. The gene modules related to the sample were identified by weighted gene co-expression network analysis (WGCNA), and genes in modules highly corelated with IH group were mainly enriched in immune related pathways. Nine DEGs were selected for validation by quantitative real time PCR (qRT-PCR) and the expression profiles of these DEGs kept a well consistent with the high-throughput data, which confirmed reliability of transcriptome results. Additionally, 10 DEGs were screened to detect the changes of expression level in different groups. All these results indicated that Zn exposure could damage the intestinal barrier, provoke oxidative stress, reduce the immune function, increase the susceptibility to bacterial infections of L. vannamei and cause inflammation, ultimately result in cell apoptosis. Our study provides more perspective on the stress response of crustacean under Zn exposure.

Shrimp injection with dsRNA targeting the microsporidian EHP polar tube protein reduces internal and external parasite amplification

The microsporidian Enterocytozoon hepatopenaei (EHP) is a major threat to shrimp health worldwide. Severe EHP infections in shrimp cause growth retardation and increase susceptibility to opportunistic infections. EHP produces spores with a chitin wall that enables them to survive prolonged environmental exposure. Previous studies showed that polar tube extrusion is a prerequisite for EHP infection, such that inhibiting extrusion should prevent infection. Using a proteomic approach, polar tube protein 2 of EHP (EhPTP2) was found abundantly in protein extracts obtained from extruded spores. Using an immunofluorescent antibody against EhPTP2 for immunohistochemistry, extruded spores were found in the shrimp hepatopancreas (HP) and intestine, but not in the stomach. We hypothesized that presence of EhPTP2 might be required for successful EHP spore extrusion. To test this hypothesis, we injected EhPTP2-specific double-stranded RNA (dsRNA) and found that it significantly diminished EHP copy numbers in infected shrimp. This indicated reduced amplification of EHP-infected cells in the HP by spores released from previously infected cells. In addition, injection of the dsRNA into EHP-infected shrimp prior to their use in cohabitation with naïve shrimp significantly (p < 0.05) reduced the rate of EHP transmission to naïve shrimp. The results revealed that EhPTP2 plays a crucial role in the life cycle of EHP and that dsRNA targeting EHP mRNA can effectively reach the parasite developing in host cells. This approach is a model for future investigations to identify critical genes for EHP survival and spread as potential targets for preventative and therapeutic measures in shrimp.

Intestine bacterial community affects the growth of the Pacific white shrimp (Litopenaeus vannamei).

Increasing evidence suggests that intestine microorganisms are closely related to shrimp growth, but there is no existing experiment to prove this hypothesis. Here, we compared the intestine bacterial community of fast- and slow-growing shrimp at the same developmental stage with a marked difference in body size. Our results showed that the intestine bacterial communities of slow-growing shrimp exhibited less diversity but were more heterogeneous than those of fast-growing shrimp. Uncultured_bacterium_g_Candidatus Bacilloplasma, Tamlana agarivorans, Donghicola tyrosinivorans, and uncultured_bacterium_f_Flavobacteriaceae were overrepresented in the intestines of fast-growing shrimp, while Shimia marina, Vibrio sp., and Vibrio campbellii showed the opposite trends. We further found that the bacterial community composition was significantly correlated with shrimp length, and some bacterial species abundances were found to be significantly correlated with shrimp weight and length, including T. agarivorans and V. campbellii, which were chosen as indicators for a reverse gavage experiment. Finally, T. agarivorans was found to significantly promote shrimp growth after the experiment. Collectively, these results suggest that intestine bacterial community could be important factors in determining the growth of shrimp, indicating that specific bacteria could be tested in further studies against shrimp growth retardation. KEY POINTS: • A close relationship between intestine bacterial community and shrimp growth was proven by controllable experiments. • The bacterial signatures of the intestine were markedly different between slow- and fast-growing shrimp, and the relative abundances of some intestine bacterial species were correlated significantly with shrimp body size. • Reverse gavage by Tamlana agarivorans significantly promoted shrimp growth.

Prospection of strains of Bacillus sporogenes in the digestive tract of native crustaceans and characterization of the probiotic potential.

The cultivation of marine shrimp is one of the fastest growing activities in the world. However, the emergence of diseases has resulted in a decrease in production and losses for the sector. Probiotics emerged as an option to the use of antibiotics to control these pathogens. The efficiency of applying this technology depends on the characteristics of the bacterial agents and their bioavailability in the shrimp intestine. The objective is to evaluate the viability and efficiency of bacteria isolated from the digestive tract of healthy crustaceans as probiotic agents in the cultivation of shrimp Litopenaeus vannamei. Eighteen strains of the genus Bacillus belonging to the following species were tested: Bacillus sp., B. cereus, B. thuringiensis, B. circulans, B. megaterium, B. subtilis and B. agaridevorans. Bacterial isolates were subjected to characterization as potential probiotics. The test results were considered satisfactory; thus, the tested strains have potential for use as probiotics in shrimp culture. Treatments that used of the genus Bacillus had reduced growth of the genus Vibrio after infection, both in the intestinal contents and in the intestine. With the results obtained, it can be suggested that further research be carried out on the probiotic potential of Bacillus sp.

The growth, survival and intestinal bacteria in white shrimp (Litopenaeus vannamei) with addition of probiotics, prebiotics and synbiotics in Feeds

White shrimp (Litopenaeus vannamei) aquaculture faces many disease problems. The use of antibiotics to treat diseases leads to the development of antibiotic-resistant bacteria, which can endanger human health. To overcome this problem, probiotics, prebiotics and synbiotics are eco-friendly solutions that can be used in shrimp aquaculture to improve water quality, growth, survival and disease resistance. This study aimed to determine the effect of probiotics, prebiotics, and synbiotics on growth, survival, and intestinal bacteria in white shrimp (L. vannamei). The experiment was conducted using a laboratory experimental method with a completely randomized design consisted of 4 treatments and 4 replications. (K) Without supplementation of probiotics, prebiotics, and synbiotics in feed; (Pro) Supplementation of probiotics in feed; (Pre) Supplementation of prebiotics in feed; and (Syn) Supplementation of synbiotics in feed. The parameters measured were SGR, FCR, SR, total lactic acid bacteria and vibrio dominance. The data were analyzed using One-Way ANOVA with SPSS version 25 and a 95% confidence interval. If the results had a significant effect (P&lt;0,05), Duncan's test was used to determine differences between treatments. The results showed that probiotic and synbiotic treatments gave the best results on SGR, FCR, SR, total lactic acid bacteria and vibrio dominance compared to the control treatment. This study concluded that added probiotics and synbiotics in feed can increase total lactic acid bacteria and reduce the dominance of vibrio in the intestines of white shrimp, as well as increase the growth and survival of white shrimp (L. vannamei).

Dietary administration of yeast (Saccharomyces cerevisiae) hydrolysate from sugar byproducts promotes the growth, survival, immunity, microbial community and disease resistance to VP (AHPND) in Pacific white shrimp (Litopenaeus vannamei)

This study investigated the effects of yeast hydrolysate (YH) from sugar byproducts on various parameters in Pacific white shrimp (Litopenaeus vannamei). The study found no significant differences in water quality parameters across all treatment tanks, ensuring that the observed effects were not due to environmental variations. There were no significant differences in growth parameters between the control group and groups receiving YH at different dosages. However, the group given YH at 10.0 g/kg feed exhibited a notably higher survival rate and higher expression of growth-related genes (IGF-2 and RAP-2A) in various shrimp tissues. YH was associated with enhanced immune responses, including lysozyme activity, NBT dye reduction, bactericidal activity, and phagocytic activity. Notably, the 10.0 g/kg feed group displayed the highest phagocytic index, indicating a dose-dependent immune response. Expression of immune-related genes (ALF, LYZ, ProPO, and SOD) was upregulated in various shrimp tissues. This upregulation was particularly significant in the gills, hepatopancreas, intestine, and hemocytes. While total Vibrio counts remained consistent, a reduction in green Vibrio colonies was observed in the intestine of shrimp treated with YH. YH, especially at 5.0 and 10.0 g/kg feed dosages, significantly increased survival rates and RPS values in response to AHPND infection. The findings of this study suggest that incorporating additives derived from yeast byproducts with possible prebiotic properties obtained from sugar byproducts can lead to positive results in terms of enhancing growth performance, immunity, histological improvements, and resistance to V. parahaemolyticus, the causative agent of acute hepatopancreatic necrosis disease (AHPND).

Tapping Chlorella vulgaris potential for enhanced growth, immunity, digestion, microbiota, and immunometabolism in Litopenaeus vannamei feeding across varied salinities

This study explored the use of Chlorella vulgaris (CHL) in Litopenaeus vannamei under varying salinity conditions. Juvenile L. vannamei (initial weight 0.38 ± 0.01 g) were fed experimental diets for 8 weeks at different salinity levels: low (15‰), moderate (30‰), and high (45‰). The control diet contained 589 g/kg fishmeal (FM) as the sole protein source, while experimental diets included 150 g/kg FM and 492 g/kg CHL as protein sources. Results revealed that shrimp fed with CHL showed a robust survival rate even at higher salinities. Following a Vibrio parahaemolyticus infection challenge, shrimp fed with CHL exhibited higher survival rates than those fed with FM at equivalent salinities. Enzyme activity and gene expression analyses indicated that CHL enhanced immune response and digestion in L. vannamei compared to the FM, even under similar salinity conditions. Additionally, shrimp fed with CHL outperformed those fed with FM under varying salinity stress. Microbiota analysis revealed increased diversity and beneficial bacteria in the intestines of shrimp fed with CHL at the same salinity levels. Transcriptomic sequencing identified genes with differential expression (DEGs) related to immune and metabolic pathways. Furthermore, a combined analysis of microbiota and DEGs revealed that CHL also had a beneficial impact on the composition of the intestinal microbiota and controlled the expression of genes related to immune and metabolic pathways. In summary, CHL as a primary protein source improved survival rate, disease resistance, immune response, and digestion in L. vannamei, positively impacting intestinal microbiota and gene expression, and enhancing adaptability to salinity changes.

Integrated Analysis of the Intestinal Microbiota and Transcriptome of Fenneropenaeus chinensis Response to Low-Salinity Stress.

Salinity is an important environmental stress factor in mariculture. Shrimp intestines harbor dense and diverse microbial communities that maintain host health and anti-pathogen capabilities under salinity stress. In this study, 16s amplicon and transcriptome sequencing were used to analyze the intestine of Fenneropenaeus chinensis under low-salinity stress (15 ppt). This study aimed to investigate the response mechanisms of the intestinal microbiota and gene expression to acute low-salinity stress. The intestinal tissues of F. chinensis were analyzed using 16S microbiota and transcriptome sequencing. The microbiota analysis demonstrated that the relative abundances of Photobacterium and Vibrio decreased significantly, whereas Shewanella, Pseudomonas, Lactobacillus, Ralstonia, Colwellia, Cohaesibacter, Fusibacter, and Lachnospiraceae_NK4A136_group became the predominant communities. Transcriptome sequencing identified numerous differentially expressed genes (DEGs). The DEGs were clustered into many Gene Ontology terms and further enriched in some immunity- or metabolism-related Kyoto Encyclopedia of Genes and Genomes pathways, including various types of N-glycan biosynthesis, amino acid sugar and nucleotide sugar metabolism, and lysosome and fatty acid metabolism. Correlation analysis between microbiota and DEGs showed that changes in Pseudomonas, Ralstonia, Colwellia, and Cohaesibacter were positively correlated with immune-related genes such as peritrophin-1-like and mucin-2-like, and negatively correlated with caspase-1-like genes. Low-salinity stress caused changes in intestinal microorganisms and their gene expression, with a close correlation between them.

The shrimp C-type lectins modulate intestinal microbiota homeostasis in microsporidia infection

Enterocytozoon hepatopenaei (EHP) is abundant in the shrimp hepatopancreas and intestines and can be transmitted through the digestive system. But the relationship between EHP and intestines or gut microbiota is still unclear. In this study, the microbiome and proteome of shrimp Penaeus vannamei intestine were used to analyze the changes of the gut microbiome and the immune protein after EHP infection. Our results showed that EHP infection brought about a marked increase in the proportion of pathogenic bacteria, such as Shigella, Aeromonas, Faecalibacterium, and Streptococcus, suggesting that EHP infection would lead to the increasing of pathogenic bacteria. Proteome results indicated showed that down-regulated proteins were mainly concentrated in immune-related domains such as C-type lectins (CTLs), hemoglobin, and glutathione transferase, suggesting that EHP might lead to a weakening of the innate immunity of shrimp. In shrimp, CTLs can involve in innate immunity by regulating the transcription of various antimicrobial peptides, and directly participate in the inhibition of pathogens through binding and agglutination. On this basis, after successfully cloned and recombination expressed, three down-regulated CTLs (perlucin, mannose receptor 1 and c-type lectin domain family 17 with typical CTL domains) were proved to have binding and agglutinin ability against four pathogenic bacteria (Enterococcus faecalis, Shigella castellani, Salmonella enteritidis, Aeromonas hydrophila). These results suggested that EHP infection led to decrease the expression of three CTLs and increase secondary infection caused by pathogenic bacteria. And CTLs played important roles in maintaining the balance of shrimp gut microbiome in microsporidia infection. In a word, these results are helpful for us to better understand the interaction between EHP and intestinal microbiota of P. vannamei and will gain new insights into prevention and control of hepatopancreatic microsporidiosis.