The use of customised probiotics in the cultivation of western king prawns (Penaeus latisulcatus Kishinouye, 1896)

A Novel Disease (Water Bubble Disease) of the Giant Freshwater Prawn Macrobrachium rosenbergii Caused by Citrobacter freundii: Antibiotic Treatment and Effects on the Antioxidant Enzyme Activity and Immune Responses

The giant freshwater prawn, Macrobrachium rosenbergii, is an important and economical aquaculture species widely farmed in tropical and subtropical areas of the world. A new disease, “water bubble disease (WBD)”, has emerged and resulted in a large loss of M. rosenbergii cultured in China. A water bubble with a diameter of about 7 mm under the carapace represents the main clinical sign of diseased prawns. In the present study, Citrobacter freundii was isolated and identified from the water bubble. The optimum temperature, pH, and salinity of the C. freundii were 32 °C, 6, and 1%, respectively. A challenging experiment showed that C. freundii caused the same typical signs of WBD in prawns. Median lethal dose of the C. freundii to prawn was 104.94 CFU/g. According to the antibiogram tests of C. freundii, florfenicol and ofloxacin were selected to evaluate their therapeutic effects against C. freundii in prawn. After the challenge with C. freundii, 86.67% and 72.22% survival of protective effects against C. freundii were evaluated in the oral florfenicol pellets and oral ofloxacin pellets feding prawns, respectively, whereas the mortality of prawns without fed antibiotics was 93%. After antibiotic treatment and C. freundii infection, the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), malondialdehyde (MDA), acid phosphatase (ACP), alkaline phosphatase (ALP), and lysozyme (LZM) in the hemolymph and hepatopancreas of the prawns and the immune-related gene expression levels of Cu/Zn-SOD, CAT, GPx, GST, LZM, ACP, anti-lipopolysaccharide factor, crustin, cyclophilin A, and C-type lectin in hepatopancreas were all significantly changed, indicating that innate immune responses were induced by C. freundii. These results can be beneficial for the prevention and control of C. freundii in prawns.

Vibrio and major commercially important vibriosis diseases in decapod crustaceans

Bacteria fromthe Vibriogenus are autochthonous to aquatic environments and ubiquitous in aquaculture production systems. Many Vibrio species are non-pathogenic and can be commonly found in healthy farmed aquatic animals. However, some Vibrio species and strains are pathogenic leading to a variety of 'vibriosis' diseases. These diseases can have a significant negative impact on animal production, including farmed crustaceans such as shrimps, lobsters, and crabs. As such, vibriosis can pose a threat to meeting growing food demand and global food security. Preventive management is essential to avoid the onset of vibriosis. This includes a robust health management plan, the use of prophylaxis and treatment measures, and enhancing animal health through nutrition. Furthermore, the use of probiotics, prebiotics, synbiotics, quorum sensing disruption, green water, biofloc, bacteriophages, and immune priming could also play a role in preventing and controlling a vibriosis outbreak. This review aims to inform and update the reader about the current state of knowledge about Vibrio and associated vibriosis in farmed crustaceans (i.e. shrimp, lobster, and crabs). Furthermore, the review will identify potential knowledge gaps in the literature, which serves as a basis for future research priorities.

Probiotics as Means of Diseases Control in Aquaculture, a Review of Current Knowledge and Future Perspectives

Along with the intensification of culture systems to meet the increasing global demands, there was an elevated risk for diseases outbreak and substantial loss for farmers. In view of several drawbacks caused by prophylactic administration of antibiotics, strict regulations have been established to ban or minimize their application in aquaculture. As an alternative to antibiotics, dietary administration of feed additives has received increasing attention during the past three decades. Probiotics, prebiotics, synbiotics and medicinal plants were among the most promising feed supplements for control or treatments of bacterial, viral and parasitic diseases of fish and shellfish. The present review summarizes and discusses the topic of potential application of probiotics as a means of disease control with comprehensive look at the available literature. The possible mode of action of probiotics (Strengthening immune response, competition for binding sites, production of antibacterial substances, and competition for nutrients) in providing protection against diseases is described. Besides, we have classified different pathogens and separately described the effects of probiotics as protective strategy. Furthermore, we have addressed the gaps of existing knowledge as well as the topics that merit further investigations. Overall, the present review paper revealed potential of different probiont to be used as protective agent against various pathogens.

Rhizosphere pseudomonads as probiotics improving plant health

Many root-colonizing microbes are multifaceted in traits that improve plant health. Although isolates designated as biological control agents directly reduce pathogen growth, many exert additional beneficial features that parallel changes induced in animal and other hosts by health-promoting microbes termed probiotics. Both animal and plant probiotics cause direct antagonism of pathogens and induce systemic immunity in the host to pathogens and other stresses. They also alter host development and improve host nutrition. The probiotic root-colonizing pseudomonads are generalists in terms of plant hosts, soil habitats and the array of stress responses that are ameliorated in the plant. This article illustrates how the probiotic pseudomonads, nurtured by the carbon (C) and nitrogen (N) sources released by the plant in root exudates, form protective biofilms on the root surface and produce the metabolites or enzymes to boost plant health. The findings reveal the multifunctional nature of many of the microbial metabolites in the plant-probiotic interplay. The beneficial effects of probiotics on plant function can contribute to sustainable yield and quality in agricultural production.

Moving from Histopathology to Molecular Tools in the Diagnosis of Molluscs Diseases of Concern under EU Legislation

One of the main factors limiting molluscs production is the presence of pathogens and diseases. Disease agent transfer via transfers of live molluscs has been a major cause of disease outbreaks and epizootics. Because of that, the European Union has adopted several decisions and directives, the last in 2006 (2006/88/EC) to control movements of marine organisms over the European countries. Once the disease is established in a determined area its eradication is a complicated task because life cycle of pathogens are not completely known and only a good and early diagnosis of the disease could be the most appropriate way to deal with it. Besides, molluscs do not have an adaptive immune response and vaccination strategies are not possible. Molluscs listed diseases under EU legislation are mainly protozoan parasites, that's why histological techniques are recognized for their diagnosis. However, molecular techniques are being increasingly used primarily as confirmatory techniques of the presence of the pathogens but also in disease monitoring programs. Research perspectives are mainly focussed in the optimization, of the already described techniques to gain in sensitivity and sensibility and in the development of new molecular biology techniques (quantitative real time PCRs), that are faster and easier to apply and that allow a positive diagnosis even in early stages of infection. However, molecular tools detect DNA sequences of the pathogen which does not imply that pathogen is viable in the cell host and the infection is established. Consequently, it needs to be validated against other techniques, such as histology or in situ hybridization, so that its reliability can be determined.

Heat-killed whole-cell products of the probiotic Pseudomonas aeruginosa VSG2 strain affect in vitro cytokine expression in head kidney macrophages of Labeo rohita

Present study was undertaken to investigate the efficiency of heat-killed whole-cell products (HKWCPs) of probiotic Pseudomonas aeruginosa VSG2 strain in stimulating the cytokine responses in the head kidney (HK) macrophages of Labeo rohita. The HK macrophages were incubated with HKWCPs or lipopolysaccharide (LPS), and the responses of cytokine genes, namely interleukin-10 (IL-10), IL-1β, IL-p35, IL-12p40, tumour necrosis factor-α (TNF-α), nuclear factor kappa B (NF-κB), cyclooxygenase-2 (COX-2), interferon-alpha (IFN-α), and interferon-gamma (IFN-γ) were assessed by quantitative real-time PCR (qRT-PCR) at 2, 8, 16, 24, 48, 72 h post-stimulation (hps). Among proinflammatory cytokines, significantly higher expression of IL-1β and TNF-α was observed at 8-24 hps, and 2-16 hps with HKWCPs, respectively, as compared to controls. However, COX-2 and NF-κB displayed strong expression (P < 0.05) at 2-8 hps, and 8, 16 and 72 hps with HKWCPs, respectively. Antiviral cytokines IFN-α and IFN-γ displayed strong expression (P < 0.05) at 8-24 hps, and 2, 24 and 48 hps with HKWCPs, respectively. Expressions of cell-mediated immune factor genes (IL-12p35 and IL-12p40) were also significantly upregulated at various time points, except IL-12p40 at 72 hps, in HK macrophages stimulated with HKWCPs. Expression of the anti-inflammatory cytokine IL-10 was upregulated (P < 0.05) at 2-24 hps HKWCPs, compared to controls. Enhanced cellular (phagocytic activity and superoxide anion production) and humoral (lysozyme) immune parameters of treated HK macrophages confirmed the induction of inflammatory response. Thus, our results indicated that HKWCPs of probiotic P. aeruginosa VSG2 had greater potential for stimulating the in vitro expression of cytokines in fish and that these HKWCPs may be used as vaccine adjuvants in aquaculture.

Live and Heat-Killed Lactobacillus rhamnosus ATCC 7469 May Induce Modulatory Cytokines Profiles on Macrophages RAW 264.7

This study aimed to evaluate the capacity of Lactobacillus rhamnosus and/or its products to induce the synthesis of cytokines (TNF-α, IL-1β, IL-4, IL-6, IL-10, and IL-12) by mouse macrophages (RAW 264.7). Three microorganism preparations were used: live L. rhamnosus (LLR) suspension, heat-killed L. rhamnosus (HKLR) suspension, and the supernatant of a heat-killed L. rhamnosus (SHKLR) suspension, which were cultured with macrophages (37°C, 5% CO₂) for 2 h and 30 min. After that, cells were cultured for 16 h. The supernatants were used for the quantitation of cytokines, by ELISA. The results were compared with the synthesis induced by lipopolysaccharide (LPS) and analysed, using ANOVA and Tukey test, 5%. LLR and HKLR groups were able to significantly increase the production of TNF-α, IL-6, and IL-10 (P < 0.05). SHKLR also significantly increased the production of TNF-α and IL-10 (P < 0.05) but not IL-6 (P > 0.05). All the L. rhamnosus suspensions were not able to produce detectable levels of IL-1β or significant levels of IL-4 and IL-12 (P > 0.05). In conclusion, live and heat-killed L. rhamnosus suspensions were able to induce the synthesis of different cytokines with proinflammatory (TNF-α and IL-6) or regulatory (IL-10) functions, suggesting the role of strain L. rhamnosus ATCC 7469 in the modulation or in the stimulation of immune responses.

Immune system stimulation by probiotic microorganisms

Probiotic organisms are claimed to offer several functional properties including stimulation of immune system. This review is presented to provide detailed informations about how probiotics stimulate our immune system. Lactobacillus rhamnosus GG, Lactobacillus casei Shirota, Bifidobacterium animalis Bb-12, Lactobacillus johnsonii La1, Bifidobacterium lactis DR10, and Saccharomyces cerevisiae boulardii are the most investigated probiotic cultures for their immunomodulation properties. Probiotics can enhance nonspecific cellular immune response characterized by activation of macrophages, natural killer (NK) cells, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in strain-specific and dose-dependent manner. Mixture and type (gram-positive and gram-negative) of probiotic organisms may induce different cytokine responses. Supplementation of probiotic organisms in infancy could help prevent immune-mediated diseases in childhood, whereas their intervention in pregnancy could affect fetal immune parameters, such as cord blood interferon (IFN)-γ levels, transforming growth factor (TGF)-β1 levels, and breast milk immunoglobulin (Ig)A. Probiotics that can be delivered via fermented milk or yogurt could improve the gut mucosal immune system by increasing the number of IgA(+) cells and cytokine-producing cells in the effector site of the intestine.

Bioactive compound from Pseudomonas synxantha inhibits the growth of Mycobacteria

Tuberculosis is a dreaded disease and the current situation demands new anti-tubercular agent(s) for the management of public health. Towards this direction, we obtained a contaminant organism on a Mycobacterium smegmatis lawn having growth inhibitory activity against the later. In the current study, efforts were targeted to identify this organism and characterize the bioactive compound from this isolate that inhibited the growth of Mycobacteria. The result revealed that the organism is a strain of Pseudomonas synxantha. Biophysical analyses including (1)H and (13)C NMR, ESI-mass spectroscopy, FTIR showed that the bioactive compound is a long chain aliphatic hydrocarbon with a terminal alyl bond and intermediate electronegative atom. The compound exhibited strong growth inhibitory activities against M. smegmatis and Mycobacterium tuberculosis strains H37Ra, H37Rv and BCG. Further experiments showed that both P. synxantha and its secretory metabolites are capable of inducing hemolysis of human blood. Thus the results of this study clearly indicate that the bioactive compound produced by P. Synxantha has biosurfactant activities as well as anti-myco-bacterial properties.

Immunological responses of customised probiotics-fed marron, Cherax tenuimanus, (Smith 1912) when challenged with Vibrio mimicus

A two-phased experiment was conducted to investigate the effects of dietary supplementation of customised probiotics on marron physiology. During the first phase marron were fed probiotic supplemented feed for 70 days, while in phase two the same marron were challenged with Vibrio mimicus and their physiological responses were investigated for 4 days post-challenged. The experiment was carried out in a purpose-built room, designed for aquaculture research, using 18 of 250 L cylindrical plastic tanks. Five species of isolated probiotic bacteria from commercial probiotic products and marron's intestine were tested in this experiment. The probiotic bacteria were (Bacillus sp.); A10 (Bacillus mycoides); A12 (Shewanella sp.); PM3 (Bacillus subtilis); and PM4 (Bacillus sp.), which were added to the formulated basal marron diet (34% crude protein, 8% crude lipid, 6% ash) at a concentration of 10(8) cfu/g of feed. Immune responses of marron fed probiotics were evaluated by investigating organosomatic indices, growth rate, survival, intermoult period, total haemocytes counts (THC), proportion of granular cells (GC), bacteraemia, bacteria load in the intestine and water quality. The results showed that dietary supplementation of probiotics in marron had no significant impact on growth, intermoult period and survival of the marron. However, their supplementation improved the physiological condition of marron in terms of significantly higher tail muscle indices, THC and proportion of granular cells (GC) and reduced bacterial load in the haemolymph. The addition of probiotics in marron diets also increased the bacteria load in the marron intestine. In addition, dietary supplementation of the customised probiotics was effective in improving the resistance of marron against V. mimicus as they had higher THC, higher proportion of GC and lower presence of bacteria in their haemolymph, after marron were challenged with V. mimicus. The results also showed that probiotic Bacillus mycoides (A10) and PM4 are the most beneficial dietary probiotics for marron health.