Shrimp production, the most important diseases that threaten it, and the role of probiotics in confronting these diseases: A review

Prevalence and molecular characterization of Acute hepatopancreatic necrosis disease (AHPND) in cultured white-leg shrimp Litopenaeus vannamei with the fungal bioactive control strategy

Mass mortalities with clinical signs characteristic of acute hepatopancreatic necrosis disease (AHPND) were reported in cultured Litopenaeus vannamei from three Egyptian farms: Wadi-Mariote, Berket Ghalyoun, and Qarun Lake. During 4-month surveillance in 2023, shrimp samples were collected to investigate the prevalence of AHPND-causing Vibrio parahaemolyticus (VpAHPND) based upon phenotypic identification, PCR, and DNA sequencing of pirA genes and pirB toxin genes followed by maximum likelihood phylogenetic analysis. In addition, the pathogenicity of V. parahaemolyticus was evaluated through the injection challenge and histopathological examination. Moreover, the antibacterial activity of marine fungal extracts against identified V. parahaemolyticus was also assessed. Molecular analysis confirmed both pirA (282 bp) and pirB (392 bp) toxin genes in the bacterial isolates. A significant positive correlation (P < 0.05) was found between V. parahaemolyticus levels in shrimp and pond water samples throughout the study period. Injection challenge with 2.7 × 104 CFU bacterial suspension resulted in 63.33 % mortality in challenged shrimp, with typical AHPND clinical signs. The histopathological examination revealed degenerative changes, including atrophy, necrosis, and sloughing of hepatopancreatic tubule epithelial cells, along with loss of functional hepatopancreatic cells. Among 11 fungal isolates screened for anti-vibrio activity, Aspergillus niger HMA9 showed the strongest inhibitory effect against V. parahaemolyticus. This study provides the first genetic confirmation of pirA and pirB toxin genes in VpAHPND as the cause of L. vannamei mass mortalities in Egypt. Further, it demonstrates the potential of fungal bioactive compounds for controlling AHPND in shrimp aquaculture.

Animal welfare risks from commercial practices involving cephalopod molluscs and decapod crustaceans

There is increasing recognition that the welfare needs of cephalopod molluscs and decapod crustaceans are important. Current commercial practices involving these animals include a range of potential threats to their welfare, such as conditions of farming, capture, transport, and slaughter. This article draws from and updates our 2021 review for the UK Government, recommending a range of relatively simple and impactful changes that could benefit welfare while highlighting important research gaps that should be prioritised to facilitate the drafting of guidelines for best-practice.

Alternatives to antibiotics against coccidiosis for poultry production: the relationship between immunity and coccidiosis management – a comprehensive review

Avian coccidiosis is a protozoan infection caused by numerous Eimeria parasitic species and mainly affects the bird’s gastrointestinal tract and results in a reduction of the bird ‘ability to absorb nutrients, slower growth, with a higher mortality rate. According to recent research, immune-based treatments, such as dietary immunomodulating feed additives and recombinant vaccines, can help the hosts protect themselves from intracellular parasites and reduce inflammatory reactions caused by parasites. Coccidiosis control in the post-antiparasitic stage requires thoroughly investigation of the intricate relationships between the parasites, host defense system, enteroendocrine system, and gut microbiome contributing to coccidian infections. To produce a vaccine, it is crucial to explore the defense mechanism of the intestine’s immune machinery and to identify many effector molecules that act against intracellular parasites. Due to the massive usage of chemical anticoccidial drugs, coccidiosis developed resistant against most commonly used anticoccidials; therefore, numerous researches focused on the usage of safe natural anticoccidials such as probiotics, prebiotics, organic acids, and essential oils to counteract such resistance problem. This review describes how host immunity responds to coccidial infection in chickens and the use of some nonantiparasitic safe natural alternative controls to counter the disease. It would throw the light on the possibility of developing effective therapies against Eimeria to alleviate the detrimental effects of avian coccidiosis.

Occupational health safety in aquaculture: A case study on semi-intensive shrimp farmers of Bangladesh

The study examined health safety issues among semi-intensive shrimp farmers in southwestern Bangladesh. The study assessed semi-intensive shrimp farmers' knowledge, attitudes, and practices (KAP) on health and safety during their farm activities. The KAP model examined working circumstances, exposures, health complaints, diseases, current health status, and job satisfaction. Face-to-face interviews were conducted with 158 semi-intensive shrimp farmers from Bangladesh's Khulna, Satkhira, and Bagerhat districts. Type-based data analysis was done. We used Spearman's rank correlation and multiple linear regression. Only 35% of respondents said that they knew the health safety of chemicals and pesticides used in semi-intensive shrimp farms and that safety training is needed, and all farmers wanted to attend when available. At least 74% of farmers used masks when handling pesticides, fertilizers, and chemicals. 40.50% of farmers used protective clothing, 91% cleansed their hands, legs, and face after each day's work, and 94% felt that sanitization reduces pesticide, fertilizer, and chemical pollution. A significant positive correlation coefficient was established in KAP. Education significantly increased knowledge. Practices varied with health and safety training. Results suggest that attitudes determine practices, where knowledge is significantly associated with attitudes. A comprehensive health safety and hygiene training program for all shrimp farmers should be developed to raise awareness, reduce illness outbreaks, and preserve healthy living.

Effects of Nitrite Stress on the Antioxidant, Immunity, Energy Metabolism, and Microbial Community Status in the Intestine of Litopenaeus vannamei

Nitrite is the main environmental pollutant that endangers shrimp culture. Intestinal health is essential for the disease resistance of shrimp. In this study, Litopenaeus vannamei shrimps were separately exposed to 1 and 5 mg/L of nitrite stress for 48 h, and then the variations in intestinal health were investigated from the aspects of histology, antioxidant, immunity, energy metabolism, and microbial community status. The results showed that nitrite stress damaged intestinal mucosa, and 5 mg/L of nitrite induced more obvious physiological changes than 1 mg/L. Specifically, the relative expression levels of antioxidant (ROMO1, Nrf2, SOD, GPx, and HSP70), ER stress (Bip and XBP1), immunity (proPO, Crus, ALF, and Lys), inflammation (JNK and TNF-α), and apoptosis (Casp-3 and Casp-9) genes were increased. Additionally, intestinal energy metabolism was activated by inducing glucose metabolism (HK, PK, PDH, and LDH), lipid metabolism (AMPK and FAS), tricarboxylic acid cycle (MDH, CS, IDH, SDH, and FH), and electron transfer chain (NDH, CytC, COI, CCO, and AtpH) gene transcription. Further, the homeostasis of intestinal microbiota composition was also disturbed, especially the abundance of some beneficial genera (Clostridium sensu stricto 1, Faecalibacterium, Romboutsia, and Ruminococcaceae UCG-010). These results reveal that nitrite stress could damage the intestinal health of L. vannamei by destroying mucosal integrity, inducing oxidation and ER stress, interfering with physiological homeostasis and energy metabolism, and disrupting the microbial community.

Compound isolation through bioassay-guided fractionation of Tectona grandis leaf extract against Vibrio pathogens in shrimp

Tectona grandis Linn, commonly known as teak, is traditionally used to treat a range of diseases, including the common cold, headaches, bronchitis, scabies, diabetes, inflammation, and others. The present study was conducted with the purpose of isolating and identifying the active compounds in T. grandis leaf against a panel of Vibrio spp., which may induce vibriosis in shrimp, using bioassay-guided purification. The antimicrobial activity was assessed using the microdilution method, followed by the brine shrimp lethality assay to determine toxicity. Following an initial screening with a number of different solvents, it was established that the acetone extract was the most effective. The acetone extract was then exposed to silica gel chromatography followed by reversed-phase HPLC and further UHPLC-orbitrap-ion trap mass spectrometry to identify the active compounds. Three compounds called 1-hydroxy-2,6,8-trimethoxy-9,10-anthraquinone, deoxyanserinone B, and khatmiamycin were identified with substantial anti-microbial action against V. parahaemolyticus, V. alginolyticus, V. harveyi, V. anguillarum, and V. vulnificus. The IC50 values of the three compounds viz. 1-hydroxy-2,6,8-trimethoxy-9,10-anthraquinone, deoxyanserinone B, and khatmiamycin varied between 2 and 28, 7 and 38, and 7 and 56 μg/mL, respectively, which are as good as the standard antibiotics such as amoxicillin and others. The in vivo toxicity test revealed that the compounds were non-toxic to shrimp. The results of the study suggest that T. grandis leaf can be used as a source of bioactive compounds to treat Vibrio species in shrimp farming.

Unveiling the biofloc culture potential: Harnessing immune functions for resilience of shrimp and resistance against AHPND -causing Vibrio parahaemolyticus infection

In shrimp aquaculture, disease mitigation may be accomplished by reducing the virulence of the pathogen or by boosting the shrimp's immunity. Biofloc technology is an innovative system that improves the health and resistance of shrimp to microbial infections while providing a viable option for maintaining the quality of culture water through efficient nutrient recycling. This review aimed at demonstrating the efficacy of the biofloc system in boosting the immune responses and protective processes of shrimp against Vibrio parahaemolyticus infection, which is known to cause Acute Hepatopancreatic Necrosis Disease (AHPND). Numerous studies have revealed that the biofloc system promotes the immunological capability of shrimp by raising multiple immune -related genes e.g. prophenoloxidase, serine proteinase gene, ras-related nuclear gene and penaeidinexpression and cellular and humoral responses such as hyperaemia, prophenoloxidase activity, superoxide dismutase activity, phagocytic activity; the protection and survival of shrimp when faced with a challenge from the V. parahaemolyticus strain have been enhanced. Furthermore, the use of the biofloc system improves water quality parameters and potentially bolstering their immune and overall health to effectively resist diseases; hence, promotes the growth of shrimp. The present review suggests that biofloc can serve as an effective therapy for both preventing and supporting the management of probable AHPND infection in shrimp culture. This approach exhibits potential for the progress of sustainable shrimp farming, higher productivity, and improved shrimp health.

White feces syndrome in shrimp: Comprehensive understanding of immune system responses

White feces syndrome (WFS) is a multifactorial disease that affects global shrimp production. The diagnostic approach to identify WFS involves traditional and molecular scientific methods by examining histopathology, bioassays, PCR (polymerase chain reaction), and calorimetric estimation. The pathogenesis of WFS is closely associated with Vibrio spp., intestinal microbiota (IM) dysbiosis, and Enterocytozoon hepatopenaei (EHP). It also has caused over 10-15 % loss in the aquaculture industry and is also known to cause retardation, lethargy and slowly leading to high mortality in shrimp farms. Therefore, it is necessary to understand the molecular mechanisms processed under the association of IM dysbiosis, Vibrio spp., and EHP to analyze the impact of disease on the innate immune system of shrimp. However, only very few reviews have described the molecular pathways involved in WFS. Hence, this review aims to elucidate an in-depth analysis of molecular pathways involved in the innate immune system of shrimp and their response to pathogens. The analysis and understanding of the impact of shrimp's innate immune system on WFS would help in developing treatments to prevent the spread of disease, thereby improving the economic condition of shrimp farms worldwide.

Comprehensive analysis of predominant pathogenic bacteria and viruses in seafood products

Given the growing global demand for seafood, it is imperative to conduct a comprehensive study on the prevalence and persistence patterns of pathogenic bacteria and viruses associated with specific seafood varieties. This assessment thoroughly examines the safety of seafood products, considering the diverse processing methods employed in the industry. The importance of understanding the behavior of foodborne pathogens, such as Salmonella typhimurium, Vibrio parahaemolyticus, Clostridium botulinum, Listeria monocytogenes, human norovirus, and hepatitis A virus, is emphasized by recent cases of gastroenteritis outbreaks linked to contaminated seafood. This analysis examines outbreaks linked to seafood in the United States and globally, with a particular emphasis on the health concerns posed by pathogenic bacteria and viruses to consumers. Ensuring the safety of seafood is crucial since it directly relates to consumer preferences on sustainability, food safety, provenance, and availability. The review focuses on assessing the frequency, growth, and durability of infections that arise during the processing of seafood. It utilizes next-generation sequencing to identify the bacteria responsible for these illnesses. Additionally, it analyzes methods for preventing and intervening of infections while also considering the forthcoming challenges in ensuring the microbiological safety of seafood products. This evaluation emphasizes the significance of the seafood processing industry in promptly responding to evolving consumer preferences by offering current information on seafood hazards and future consumption patterns. To ensure the continuous safety and sustainable future of seafood products, it is crucial to identify and address possible threats.

Nanobubble applications in aquaculture industry for improving harvest yield, wastewater treatment, and disease control

The ever-growing demand for aquaculture has led the industry to seek novel approaches for more sustainable practices. These attempts aim to increase aquaculture yield by increasing energy efficiency and decreasing footprint and chemical demand without compromising animal health. For this, emerging nanobubbles (NBs) aeration technology gained attention. NBs are gas-filled pockets suspended as sphere-like cavities (bulk NBs) or attached to surfaces (surface NBs) with diameters of <1 μm. Compared to macro and microbubbles, NBs have demonstrated unique characteristics such as long residence times in water, higher gas mass transfer efficiency, and hydroxyl radical production. This paper focuses on reviewing NB technology in aquaculture systems by summarizing and discussing uses and implications. Three focus areas were targeted to review the applicability and effects of NBs in aquaculture: (i) NBs aeration to improve the aquaculture harvest yield and subsequent wastewater treatment; (ii) NB application for inactivation of harmful microorganisms; and (iii) NBs for reducing oxidative stress and improving animal health. Thus, this study reviews the research studies published in the last 10 years in which air, oxygen, ozone, and hydrogen NBs were tested to improve gas mass transfer, wastewater treatment, and control of pathogenic microorganisms. The experimental results indicated that air and oxygen NBs yield significantly higher productivity, growth rate, total harvest, survival rate, and less oxygen consumption in fish and shrimp farming. Secondly, the application of air and ozone NBs demonstrated the ability of efficient pollutant degradation. Third, NB application demonstrated effective control of infectious bacteria and viruses, and thus increased fish survival, as well as different gene expression patterns that induce immune responses to infections. Reviewed studies lack robust comparative analyses of the efficacy of macro- and microbubble treatments. Also, potential health and safety implications, as well as economic feasibility through factors such as changes in capital infrastructure, routine maintenance and energy consumption need to be considered and evaluated in parallel to applicability. Therefore, even with a promising future, further studies are needed to confirm the benefits of NB treatment versus conventional aquaculture practices.

A comprehensive review on the utilization of probiotics in aquaculture towards sustainable shrimp farming

Probiotics in shrimp aquaculture have gained considerable attention as a potential solution to enhance production efficiency, disease management, and overall sustainability. Probiotics, beneficial microorganisms, have shown promising effects when administered to shrimp as dietary supplements or water additives. Their inclusion has been linked to improved gut health, nutrient absorption, and disease resistance in shrimp. Probiotics also play a crucial role in maintaining a balanced microbial community within the shrimp pond environment, enhancing water quality and reducing pathogen prevalence. This article briefly summarizes the many ways that probiotics are used in shrimp farming and the advantages that come with them. Despite the promising results, challenges such as strain selection, dosage optimization, and environmental conditions are carefully addressed for successful probiotic integration in shrimp aquaculture. The potential of probiotics as a sustainable and ecologically friendly method of promoting shrimp development and health while advancing environmentally friendly shrimp farming techniques is highlighted in this analysis. Further research is required to fully exploit probiotics' benefits and develop practical guidelines for their effective implementation in shrimp aquaculture.

Exploring the role and mechanism of potential probiotics in mitigating the shrimp pathogens

Shrimp aquaculture has rapidly developed into a significant industry worldwide, providing not only financial gain and high-quality food but also tens of thousands of trained and competent workers. Frequent diseases are now regarded as a significant risk factor for shrimp aquaculture, as they have the potential to significantly reduce shrimp production and result in economic losses. Over the years various traditional methods including the use of antibiotics have been followed to control diseases yet unsuccessful. Probiotic is considered potential supplements for shrimps during farming, they may also act beneficially as disease control and increased production. Probiotics are described as a live microbial supplement that benefits the host by modifying the microbial population associated with the host and its ambient. The present state of research about probiotics demonstrates notable impacts on the immune defences of the host's gastrointestinal system, which play a crucial role in safeguarding against diseases and managing inflammation inside the digestive tract. In the past ten years, many studies on probiotics have been published. However, there is a lack of information about the processes by which probiotics exert their effects in aquaculture systems, with only limited elucidations being offered. This study explores the variety of procedures behind the positive effects of probiotics in shrimp culture. These mechanisms include the augmentation of the immune system, control of growth, antagonistic action against pathogens, competitive exclusion, and modification of the gut microbiota. Mechanisms involved in the probiotic mode of action are mostly interlinked. This provides a greater understanding of the importance of probiotics in shrimp culture as an environmentally friendly practice.

Evaluation of the Differential Postbiotic Potential of Shewanella putrefaciens Pdp11 Cultured in Several Growing Conditions

The increased knowledge of functional foods has led to the development of a new generation of health products, including those containing probiotics and products derived from them. Shewanella putrefaciens Pdp11 (SpPdp11) is a strain described as a probiotic that exerts important beneficial effects on several farmed fish. However, the use of live probiotic cells in aquaculture has limitations such as uncertain survival and shelf life, which can limit their efficacy. In addition, its efficacy can vary across species and hosts. When probiotics are administered orally, their activity can be affected by the environment present in the host and by interactions with the intestinal microbiota. Furthermore, live cells can also produce undesired substances that may negatively impact the host as well as the risk of potential virulence reversion acquired such as antibiotic resistance. Therefore, new alternatives emerged such as postbiotics. Currently, there is no knowledge about the postbiotic potential of SpPdp11 in the aquaculture industry. Postbiotic refers to the use of bacterial metabolites, including extracellular products (ECPs), to improve host physiology. However, the production of postbiotic metabolites can be affected by various factors such as cultivation conditions, which can affect bacterial metabolism. Thus, the objective of this study was to evaluate the postbiotic potential of ECPs from SpPdp11 under different cultivation conditions, including culture media, temperature, growth phase, and salinity. We analyzed their hydrolytic, antibacterial, antiviral, and cytotoxic capacity on several fish cell lines. The results obtained have demonstrated how each ECP condition can exert a different hydrolytic profile, reduce the biofilm formation by bacterial pathogens relevant to fish, lower the titer of nervous necrosis virus (NNV), and exert a cytotoxic effect on different fish cell lines. In conclusion, the ECPs obtained from SpPdp11 have different capacities depending on the cultivation conditions used. These conditions must be considered in order to recover the maximum number of beneficial capacities or to choose the appropriate conditions for specific activities.

Functional and genomic characterization of a novel probiotic Lactobacillus johnsonii KD1 against shrimp WSSV infection

White Spot syndrome virus (WSSV) causes rapid shrimp mortality and production loss worldwide. This study demonstrates potential use of Lactobacillus johnsonii KD1 as an anti-WSSV agent for post larva shrimp cultivation and explores some potential mechanisms behind the anti-WSSV properties. Treatment of Penaeus vannamei shrimps with L. johnsonii KD1 prior to oral challenge with WSSV-infected tissues showed a significantly reduced mortality. In addition, WSSV copy numbers were not detected and shrimp immune genes were upregulated. Genomic analysis of L. johnsonii KD1 based on Illumina and Nanopore platforms revealed a 1.87 Mb chromosome and one 15.4 Kb plasmid. Only one antimicrobial resistance gene (ermB) in the chromosome was identified. Phylogenetic analysis comparing L. johnsonii KD1 to other L. johnsonii isolates revealed that L. johnsonii KD1 is closely related to L. johnsonii GHZ10a isolated from wild pigs. Interestingly, L. johnsonii KD1 contains isolate-specific genes such as genes involved in a type I restriction-modification system and CAZymes belonging to the GT8 family. Furthermore, genes coding for probiotic survival and potential antimicrobial/anti-viral metabolites such as a homolog of the bacteriocin helveticin-J were found. Protein-protein docking modelling suggests the helveticin-J homolog may be able to block VP28-PmRab7 interactions and interrupt WSSV infection.

The effect of alginate oligosaccharides on intestine barrier function and Vibrio parahaemolyticus infections in the white shrimp Litopenaeus vannamei

The intestine is a host-pathogen interaction site and improved intestinal barrier function help to prevent disease in shrimp. Alginate oligosaccharides (AOS) are derived from resourceful brown algae. The intestine protection properties of AOS were widely recognized, and their benefits in fish have been reported. Nevertheless, there are no reports on AOS in shrimp and other crustaceans. In the present work, we measured the effects of AOS on growth performance and disease resistance in the white shrimp Litopenaeus vannamei and investigated their effects on intestinal health. Shrimps with an initial weight of about 2 g were fed with diets supplemented with 0 (control), 0.07%, 0.2%, 0.6%, or 1.2% of AOS for 56 days and were sampled and challenged with Vibrio parahaemolyticus. Dietary AOS did not significantly influence weight gain or feed utilization (P > 0.05). However, AOS considerably decreased the seven-day cumulative mortality after the challenge at any dose (P < 0.05). Dietary AOS improved the intestinal structure, significantly boosted the intestinal villus height at 0.6% and 1.2% levels, and increased intestinal wall thickness by 0.2%, 0.6%, and 1.2%. The alkaline phosphatase and maltase activities were also increased, suggesting that AOS improved the intestinal condition. Redox homeostasis in intestinal was improved by AOS, as expressed by the enhanced total antioxidant capacity and decreased malonaldehyde content, partly due to the increased superoxide dismutase and catalase activities. Compared with the antioxidant system, AOS's stimulating effects on immunity were more significant. At any level, AOS significantly activated lysozyme activity, the expression of propo and two antimicrobial peptide genes (pen-3 and crusin). However, the lowest concentration of AOS did not stimulate the gene expression of all three assayed pattern recognition receptors (LGBP, Toll, and IMD), and only the highest concentration of AOS increased the expression of imd. These findings suggest that AOS are highly efficient immunostimulants, and various immune pathways in shrimp are differentially sensitive to AOS. Finally, our findings suggest that AOS significantly alter the gut microbiota and their relative abundance at the phylum, family, and genus levels. In conclusion, AOS significantly enhances disease resistance in L. vannamei, possibly attributed to improved intestinal development, increased intestinal immunity and altered microbiota. These findings could provide a basis for future studies on the practical use of AOS and its mechanisms of action.

Epigenetic Modulations for Prevention of Infectious Diseases in Shrimp Aquaculture

Aquaculture assumes a pivotal role in meeting the escalating global food demand, and shrimp farming, in particular, holds a significant role in the global economy and food security, providing a rich source of nutrients for human consumption. Nonetheless, the industry faces formidable challenges, primarily attributed to disease outbreaks and the diminishing efficacy of conventional disease management approaches, such as antibiotic usage. Consequently, there is an urgent imperative to explore alternative strategies to ensure the sustainability of the industry. In this context, the field of epigenetics emerges as a promising avenue for combating infectious diseases in shrimp aquaculture. Epigenetic modulations entail chemical alterations in DNA and proteins, orchestrating gene expression patterns without modifying the underlying DNA sequence through DNA methylation, histone modifications, and non-coding RNA molecules. Utilizing epigenetic mechanisms presents an opportunity to enhance immune gene expression and bolster disease resistance in shrimp, thereby contributing to disease management strategies and optimizing shrimp health and productivity. Additionally, the concept of epigenetic inheritability in marine animals holds immense potential for the future of the shrimp farming industry. To this end, this comprehensive review thoroughly explores the dynamics of epigenetic modulations in shrimp aquaculture, with a particular emphasis on its pivotal role in disease management. It conveys the significance of harnessing advantageous epigenetic changes to ensure the long-term viability of shrimp farming while deliberating on the potential consequences of these interventions. Overall, this appraisal highlights the promising trajectory of epigenetic applications, propelling the field toward strengthening sustainability in shrimp aquaculture.

Therapeutic Potential of Marine Probiotics: A Survey on the Anticancer and Antibacterial Effects of Pseudoalteromonas spp

Due to the increasing limitations and negative impacts of the current options for preventing and managing diseases, including chemotherapeutic drugs and radiation, alternative therapies are needed, especially ones utilizing and maximizing natural products (NPs). NPs abound with diverse bioactive primary and secondary metabolites and compounds with therapeutic properties. Marine probiotics are beneficial microorganisms that inhabit marine environments and can benefit their hosts by improving health, growth, and disease resistance. Several studies have shown they possess potential bioactive and therapeutic actions against diverse disease conditions, thus opening the way for possible exploitation of their benefits through their application. Pseudoalteromonas spp. are a widely distributed heterotrophic, flagellated, non-spore-forming, rod-shaped, and gram-negative marine probiotic bacteria species with reported therapeutic capabilities, including anti-cancer and -bacterial effects. This review discusses the basic concepts of marine probiotics and their therapeutic effects. Additionally, a survey of the anticancer and antibacterial effects of Pseudoalteromonas spp. is presented. Finally, marine probiotic production, advances, prospects, and future perspectives is presented.

Effect of Clostridium butyricum on intestinal microbiota and resistance to Vibrio alginolyticus of Penaeus vannamei

In order to evaluate the effect of Clostridium butyricum (C. butyricum) feeding on intestinal microorganisms and protection against infection by Vibrio alginolyticus (V. alginolyticus) in Penaeus vannamei (P. vannamei). We set up two groups, CG30 (fed normal feed) and CB30 (fed feed supplemented with C. butyricum), for the 30d C. butyricum feeding test, and four groups, CG (CG30 group injected with PBS), CB (CB30 group injected with PBS), VACG (CG30 group injected with V. alginolyticus), and VACB (CB30 group injected with V. alginolyticus), for the 24h infection test. The protective effect of C. butyricum against acute V. alginolyticus infection in P. vannamei was explained in terms of survival, histopathology, changes in enzyme activity, transcriptome analysis, and immune-related genes. We found that feeding C. butyricum significantly altered intestinal microbial populations' abundance and significantly reduced Vibrio spp. In the V. alginolyticus stress test, C. butyricum improved the survival rate and alleviated pathological changes in hepatopancreatic tissues, alleviated the reduction of superoxide dismutase (SOD) and phenoloxidase (PO) activity caused by infection, and increased the lysozyme content in P. vannamei. VACB group compared with the VACG group, 1730 up-regulated differentially expressed genes (DEGs) and 2029 down-regulated DEGs were screened. Quantitative real-time PCR (qRT-PCR) showed that dietary supplementation with C. butyricum suppressed the upregulation of alkaline phosphatase (AKP) transcription factors and the downregulation of prophenoloxidase (proPO), alpha-2-macroglobulin (A2M), and anti-lipopolysaccharide factor (ALF) induced by V. alginolyticus infection. In conclusion, feed supplementation with C. butyricum changed P. vannamei's population ratio of intestinal microorganisms. Moreover, C. butyricum has the potential to act as an inhibitor of V. alginolyticus infection and enhance the resistance of P. vannamei to V. alginolyticus infection.

Investigation of the effects of cup plant (Silphium perfoliatum L.) on the growth, immunity, gut microbiota and disease resistance of Penaeus vannamei

To investigate the effects of adding different concentrations of cup plant (Silphium perfoliatum L.) to the feed on the growth performance, hepatopancreas and intestinal microstructure, gene expression, enzyme activity, as well as intestinal microorganisms and resistance to Vibrio parahaemolyticus E1 and White spot syndrome virus (WSSV) infection of the shrimp, cup plant was added to the basal feed at 1%, 3%, 5% and 7% respectively, and fed the shrimp for 6 weeks. It was found that the addition of different concentrations of cup plant could significantly improve the specific growth rate and survival rate of shrimp, reduce the feed conversion rate, and improve the resistance to V. parahaemolyticus E1 and WSSV in shrimp, with the best effect of 5% addition. The tissue sections observations showed that the addition of cup plant significantly improved the hepatopancreas and intestinal tissues of shrimp, especially in alleviating the tissue damage caused by V. parahaemolyticus E1 and WSSV infection, but too high an addition (7%) could also cause side effects on the shrimp intestinal tract. Meantime, the addition of cup plant can also increase the activity of immunodigestive-related enzymes in the hepatopancreas and intestinal tissues of shrimp, and can significantly induce the up-regulation of immune-related genes expression, and it is positively correlated with the amount of addition in a certain range. In addition, it was found that the addition of cup plant has a significant regulating effect on the intestinal flora of shrimp, which can significantly promote the growth of beneficial bacteria such as Haloferula sp., Algoriphagus sp. and Coccinimonas sp., and inhibit pathogenic bacteria Vibrio sp., such as the number of Vibrionaceae_Vibrio and Pseudoalteromonadaceae_Vibrio in the experimental group were significantly reduced, and the lowest level in the 5% addition group. In summary, the study shows that cup plant can promote the growth of shrimp, improve the resistance of shrimp to disease, and is a potential green environmental feed additive that can replace antibiotics.