Effects of a co-culture of marine algae and shrimp (Litopenaeus vannamei) on the growth, survival and immune response of shrimp infected with Vibrio parahaemolyticus and white spot virus (WSSV)

Phytochemical screening and antibacterial assessment of two macroalgae Ulva papenfussi and Ulva nematoidea (Chlorophyta) against the bacterium Vibrio parahaemolyticus

This study was conducted to determine whether the macroalgae Ulva papenfussi and Ulva nematoidea could be alternatives for preventing Litopenaeus vannamei vibriosis caused by the bacterium Vibrio parahaemolyticus. Phytochemical screening was performed on methanolic extracts to qualitatively determine the main groups of bioactive compounds, previous to an in vitro antibacterial test against V. parahaemolitycus. Phenols, polyphenols, flavonoids, and the high presence of carbohydrates were found in both macroalgae. U. papenfussi showed more presence of lipids and alkaloids than U. nematoidea. Macroalgae extracts prepared (v:v) with a 1:1 methanol: dichloromethane solvent was used for the in vitro test using the disc diffusion method (MDD). Filter paper discs impregnated with 1.0, 1.5, 2.0, 3.0, and 4.0 mg of the extracts showed antibacterial activity against V. Parahaemolitycus in a dose-dependent manner in both macroalgae. The inhibition zone varied significantly (p < 0.05) from 8.33 ± 0.12 to 11.41 ± 0.73 mm for 1 to 3 mg of extract levels, respectively. In conclusion, both macroalgae have antibacterial activity in their crude extracts against this bacteria. It is suggested to evaluate it as a feed additive for L. vannamei. This study is the first report on a phytochemical screening and antibacterial activity of these macroalgae against V. parahaemolyticus.

Shellfish-algal systems as important components of fisheries carbon sinks: Their contribution and response to climate change

In the context of global climate change, ocean acidification and warming are becoming increasingly serious. Adding carbon sinks in the ocean is an important part of efforts to mitigate climate change. Many researchers have proposed the concept of a fisheries carbon sink. Shellfish-algal systems are among the most important components of fisheries carbon sinks, but there has been limited research on the impact of climate change on shellfish-algal carbon sequestration systems. This review assesses the impact of global climate change on shellfish-algal carbon sequestration systems and provides a rough estimate of the global shellfish-algal carbon sink capacity. This review evaluates the impact of global climate change on shellfish-algal carbon sequestration systems. We review relevant studies that have examined the effects of climate change on such systems from multiple levels, perspectives, and species. There is an urgent need for more realistic and comprehensive studies given expectations about the future climate. Such studies should provide a better understanding of the mechanisms by which the carbon cycle function of marine biological carbon pumps may be affected in realistic future environmental conditions and the patterns of interaction between climate change and ocean carbon sinks.

The role of probiotics in vannamei shrimp aquaculture performance – A review

Vannamei shrimp (Litopenaeus vannamei) is an important food commodity of economic benefit due to its high price, low susceptibility to disease, and popularity for consumption. These advantages have led many farmers to cultivate vannamei shrimp. Efforts are underway to improve the aquaculture performance of this species, including the use of probiotics, which are non-pathogenic bacteria that aid in digestion and help fight disease. Probiotics are usually obtained from the intestines of vannamei shrimp or the culture environment. They are low-cost, non-pathogenic, and largely non-toxic source of antibiotics and are able to synthesize various metabolites that have antibacterial functions and applications. Research on probiotic use has primarily been focused on increasing vannamei shrimp aquaculture production. Bacterial species, such as Lactobacillus or Nitrobacter, can be administered orally, by injection, or as a supplement in aquaculture water. Probiotics help to improve survival rate, water quality, immunity, and disease resistance through space competition with disease-causing bacteria, such as Vibrio spp. An increased number of probiotic bacteria suppresses the growth and presence of pathogenic bacteria, which lowers disease susceptibility. In addition, probiotic bacteria also aid digestion by breaking down complex compounds into simpler substances that the body can absorb more easily. This mechanism improves growth performance in terms of weight, length, and feed conversion ratio. This review aimed to provide information regarding contribution of probiotic to improve vannamei shrimp production in aquaculture. Keywords: application, bacteria, farm, microbiome, shrimp.

Emerging Research Topics in the Vibrionaceae and the Squid-Vibrio Symbiosis

The Vibrionaceae encompasses a cosmopolitan group that is mostly aquatic and possesses tremendous metabolic and genetic diversity. Given the importance of this taxon, it deserves continued and deeper research in a multitude of areas. This review outlines emerging topics of interest within the Vibrionaceae. Moreover, previously understudied research areas are highlighted that merit further exploration, including affiliations with marine plants (seagrasses), microbial predators, intracellular niches, and resistance to heavy metal toxicity. Agarases, phototrophy, phage shock protein response, and microbial experimental evolution are also fields discussed. The squid-Vibrio symbiosis is a stellar model system, which can be a useful guiding light on deeper expeditions and voyages traversing these "seas of interest". Where appropriate, the squid-Vibrio mutualism is mentioned in how it has or could facilitate the illumination of these various subjects. Additional research is warranted on the topics specified herein, since they have critical relevance for biomedical science, pharmaceuticals, and health care. There are also practical applications in agriculture, zymology, food science, and culinary use. The tractability of microbial experimental evolution is explained. Examples are given of how microbial selection studies can be used to examine the roles of chance, contingency, and determinism (natural selection) in shaping Earth's natural history.

The fate of antibiotic resistance genes, microbial community, and potential pathogens in the maricultural sediment by live seaweeds and oxytetracycline

Three common seaweeds including Ulva fasciata, Codium cylindricum and Ishige okamurai were used for the remediation of maricultural wastewater and sediment in the presence/absence of trace level of oxytetracycline (OTC) in lab-scale experiments. Higher NO₃^--N and PO₄^3--P removal rates were achieved due to the presence of seaweeds, and trace OTC also had a positive effect on NO₃^--N removal. A slight variation of 2.10-2.15% were observed in the total relative abundances of antibiotic resistance genes (ARGs) of different sediment samples after one-month operation. However, the variation of ARGs profiles by the co-existence of different seaweeds and OTC was in the descending order of Ishige okamurai > Codium cylindricum > Ulva fasciata, which was in accordance with the variation of microbial hosts at genus level. The abundance of dominant tetracycline resistance genes promoted by the co-existence of different seaweeds and OTC in compared with the presence of single seaweed or OTC via metagenomic sequencing and qPCR analysis, and the co-existence of Ishige okamurai and OTC exhibited the largest impact. The potential pathogens were more sensitive to the co-existence of seaweed and OTC than single seaweeds. Meanwhile, a variety of ARGs were enriched in the pathogens, and the dominant pathogenic bacteria of Vibrio had 133 Vibrio species with 28 subtypes of ARGs. The variation of ARGs profiles in the sediment were strongly related with the dominant phyla Proteobacteria, Actinobacteria, Firmicutes, Planctomycetes and Cyanobacteria. Besides, Nitrate level exhibited more significant effect on ∑ARGs, ARGs resistant to vancomycin and streptogramin_a, while phosphate level exhibited more positively significant effect on ARGs resistant to fosmidomycin, ATFBT and cephalosporin.

Seaweeds influence oyster microbiota and disease susceptibility

A growing awareness of role that microbiota can play in mediating the effects of pathogens on hosts has given rise to the concept of the pathobiome. Recently, we demonstrated that the Pacific oyster mortality syndrome affecting Crassostrea gigas oysters is caused by infection with the Ostreid herpesvirus type 1 (OsHV-1) followed by infection with multiple bacterial taxa. Here we extend the concept of this pathobiome beyond the host species and its bacterial microbiota by investigating how seaweed living in association with oysters influences their response to the disease. We hypothesized that by their mere presence in the environment, different species of seaweeds can positively or negatively influence the risk of disease in oysters by shaping their bacterial microbiota and their immune response. Although seaweed and oysters do not have direct ecological interactions, they are connected by seawater and likely share microbes. To test our hypothesis, oysters were acclimated with green, brown or red algae for 2 weeks and then challenged with OsHV-1. We monitored host survival and pathogen proliferation and performed bacterial microbiota and transcriptome analyses. We found that seaweeds can alter the bacterial microbiota of the host and its response to the disease. More particularly, green algae belonging to the genus Ulva spp. induced bacterial microbiota dysbiosis in oyster and modification of its transcriptional immune response leading to increased susceptibility to the disease. This work provides a better understanding of a marine disease and highlights the importance of considering both macrobiotic and microbiotic interactions for conservation, management and exploitation of marine ecosystems and resources.

Effect of functional diets on intestinal microbiota and resistance to Vibrio parahaemolyticus causing acute hepatopancreatic necrosis disease (AHPND) of Pacific white shrimp (Penaeus vannamei)

AIMS

The present study evaluated the effect of four functional diets and a reference diet on the survival and intestinal bacterial community of shrimp Penaeus vannamei infected with AHPND.

METHODS AND RESULTS

After 42 days of feeding trail, shrimp were inoculated with a Vibrio parahaemolyticus (CIB-0018-3) carrying the plasmid encoding for the PirAB toxins responsible for AHPND. After 120 h post-infection (hpi), shrimp fed with a diet containing 2% of a mix with Curcuma longa and Lepidium meyenii (TuMa) and a diet containing 0.2% of vitamin C (VitC) showed a significantly higher survival (85%) compared to the remaining treatments (50-55%) (p<0.05). Infected shrimp fed with TuMa diet, showed a significant reduction of Vibrionales; and VitC diet promoted an increase of Alteromonadales.

CONCLUSIONS

Our findings suggest that the TuMa diet conferred protection against AHPND and could be attributed to a combined effect of antibacterial properties against Vibrionales, and promoting a desirable bacterial community in the shrimp intestine, while the VitC diet protection could be attributed to their antioxidant capacity and in a lower proportion to a bacterial modulation in shrimp gut.

SIGNIFICANCE AND IMPACT OF THE STUDY

Acute Hepatopancreatic Necrosis Disease (AHPND) is a devastating disease that significantly affects aquaculture production of shrimps. Therefore, the use of functional diets that promotes resistance to AHPND, represents a valuable tool to reduce the mortality of farmed shrimp.

Anti-vibrio and immune-enhancing activity of medicinal plants in shrimp: A comprehensive review

Disease epidemics in shrimp aquaculture increase apace with the development of aquaculture systems throughout the world. The disease caused by Vibrio spp. (vibriosis) is considered the most devastating, which has made it the most feared bacterial disease in the shrimp sector. In aquaculture, several strategies have already been applied to control Vibrio strains, including chemicals, probiotics, antibiotics, natural products from plants, including plant oils; hence, there has been considerable attention for using plants in shrimp aquaculture to provide sustainable, eco-friendly and safe compounds, such as alkaloids, saponins, terpenoids and flavonoids for replacing chemical compounds and antibiotics in current aquaculture. Medicinal plants may also have immunostimulating activity, increase growth and resistance in shrimps. The present paper aims to review the inhibition of Vibrio spp. in shrimp by medicinal plants, using both in vitro or/and in vivo techniques. Several medicinal plants appear capable of inhibiting growth of Vibrio pathogens outside living shrimp or in the body of shrimp, through enhancing growth and immune capacity when shrimps are fed or injected with them. In the current review Gracilaria spp. (Gracilariaceae family) and Sargassum spp. (family Sargassaceae) have been used most for in vitro and in vivo experiments. Among the terrestrial plants, Eucalyptus camaldulensis, Psidium guajava, Rhodomyrtus tomentosa, and Syzygium cumini (Myrtaceae family) had significant activity against Vibrio.

Emerging contaminants detected in aquaculture sites in Java, Indonesia

Pharmaceuticals of emerging concern (acetaminophen (ACM), trimethoprim (TMP), oxytetracycline (OTC), and sulfamethoxazole (SMX)) were detected in water samples from aquaculture environments and nonaquaculture sites in four regions located on the northern coast of Central Java. ACM was the most prevalent pharmaceutical, with a mean concentration ranging from not detected (n.d.) to 5.5 ± 1.9 ngL^-1 (Brebes). Among the target antibiotics (TMP, OTC, SMX), OTC was the most ubiquitous, with a mean concentration varying from n.d. to 8.0 ± 3.3 ngL^-1. Correlation analysis demonstrated that there was a significant correlation between TMP and SMX concentrations. Based on ecological risk assessment evaluation, the use of OTC requires serious consideration, as it presented high health risks to algae, while ACM, TMP, and SMX posed an insignificant to moderate risk to algae, invertebrates, and fish. The findings obtained from this study highlight OTC as an emerging contaminant of prominent concern. More attention needs to be given to managing and planning for the sustainable management of shrimp farms, particularly in the northern part of Central Java.

Motility, biofilm formation and associated gene expression in Vibrio parahaemolyticus impaired by co-culture with live Ulva fasciata

AIMS

Vibrio parahaemolyticus is one of the most frequently occurred pathogens in mariculture. This study aimed to explore the mechanism of the impact of Ulva fasciata on the motility and biofilm formation of V. parahaemolyticus.

METHODS AND RESULTS

The inhibitory effect of U. fasciata on a V. parahaemolyticus, isolated from clam maricultural sediment, was examined by co-culture of them. The live U. fasciata significantly inhibited the swimming behaviour, twitching behaviour and biofilm formation of V. parahaemolyticus JF, with inhibition rates range of 2.48%-20.26%, 1.59%-39.18% and 28.3%-94.7% under different nitrate and phosphate levels, respectively. The results of transcriptome sequencing showed that 210 significantly differentially expressed genes (DEGs) were found in strain JF between the presence and absence of U. fasciata, including 90 upregulated genes and 120 downregulated genes. According to GO (Gene Ontology) function enrichment and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis, the downregulated genes of JF were partially enriched in flagella assembly (fliC, fliK, fliG, fliN, fliH, fliI, fliJ and fliA), bacterial chemotaxis (mCP, cheB, cheW and cheY) and biofilm formation (fliA/σ²⁸ and eps), which explained the suppressed motility and biofilm formation of V. parahaemolyticus JF under U. fasciata stress.

CONCLUSIONS

Live U. fasciata significantly impaired the motility and biofilm formation of V. parahaemolyticus, which could occur in niches with either sufficient or inadequate nutrient (nitrate and phosphate) concentrations. The DEGs of V. parahaemolyticus modulated by U. fasciata were enriched mainly in the flagellar assembly, bacterial chemotaxis and biofilm pathways.

SIGNIFICANCE AND IMPACT OF THE STUDY

New information on how V. parahaemolyticus respond to U. fasciata regarding motility and adhesion behaviours, and the mechanism of that was firstly explored in this study. The results suggested that the seaweed U. fasciata has promising prospects as an environmentally friendly preventive measure to treat vibriosis in mariculture.

The Use of Invasive Algae Species as a Source of Secondary Metabolites and Biological Activities: Spain as Case-Study

In the recent decades, algae have proven to be a source of different bioactive compounds with biological activities, which has increased the potential application of these organisms in food, cosmetic, pharmaceutical, animal feed, and other industrial sectors. On the other hand, there is a growing interest in developing effective strategies for control and/or eradication of invasive algae since they have a negative impact on marine ecosystems and in the economy of the affected zones. However, the application of control measures is usually time and resource-consuming and not profitable. Considering this context, the valorization of invasive algae species as a source of bioactive compounds for industrial applications could be a suitable strategy to reduce their population, obtaining both environmental and economic benefits. To carry out this practice, it is necessary to evaluate the chemical and the nutritional composition of the algae as well as the most efficient methods of extracting the compounds of interest. In the case of northwest Spain, five algae species are considered invasive: Asparagopsis armata, Codium fragile, Gracilaria vermiculophylla, Sargassum muticum, and Grateulopia turuturu. This review presents a brief description of their main bioactive compounds, biological activities, and extraction systems employed for their recovery. In addition, evidence of their beneficial properties and the possibility of use them as supplement in diets of aquaculture animals was collected to illustrate one of their possible applications.

Dietary Supplementation of Brown Seaweed and/or Nucleotides Improved Shrimp Performance, Health Status and Cold-Tolerant Gene Expression of Juvenile Whiteleg Shrimp during the Winter Season

This study was aimed to evaluate the efficiency of Sargassumpolycystum and nucleotides- supplemented diets to improve immune response and cold-tolerance of juvenile Litopenaeus vannamei. Four treatments were evaluated: T1, the control, shrimp received only a basal diet; T2, a basal diet with 500 ppm nucleotides; T3, a basal diet with 500 ppm S.polycystum powdered; T4, a basal diet with 500 ppm nucleotides and 500 ppm S.polycystum powdered. Shrimp were fed experimental diets for 56 days. Results revealed shrimp fed T4 diet exhibited the best significant improvement in water quality, survival, growth, and feed utilization indices followed by T2, and T3, while T1 showed the worst values. Additionally, nonspecific immune responses (phagocytosis (%), lysozyme, phenoloxidase, super oxide dismutase (SOD) activity, total nitric oxide) were improved with 1.7-3.2-fold in T4 higher than T1. Histomorphology of hepatopancreas in T4 showed the most increased activation of the hepatic glandular duct system compared with the other treatments. Moreover, nucleotides/seaweed-supplemented diets upregulated relative expression of cMnSOD, Penaeidin4, and heat shock protein70 (HSP70) genes, while translationally controlled tumor protein (TCTP) was downregulated. In conclusion, the synergistic effects of both S. polycystum and nucleotides have many advantages as a growth promoter, immunostimulant, antimicrobial, and cold-tolerant stimulant to L. vannamei.

The role of Ulva fasciata in the evolution of the microbial community and antibiotic resistance genes in maricultural sediments

This study explored changes in the microbial community and antibiotic resistance genes (ARGs) in maricultural clam sediment after 3-month co-culture with different densities (0, 5 and 12 g L^-1) of seaweed Ulva fasciata (U. fasciata). The maximum removal rates of NO₃^--N, PO₄^3--P, and inhibition of Vibrio culturability occurred at presence of 12 g L^-1U. fasciata. A significant decrease by 14.0% of the total ARGs was found in control sediment without U. fasciata after separation from the original niches, while the total ARGs further increased by 5.58%and 4.65% at presence of 5 and 12 g L^-1 of U. fasciata in compared with control sediment, respectively, strongly related with Chloroflexi, Spirochaetes, Proteobacteria and Bacteroidetes hosts. In addition, U. fasciata favored the decline of absolute gene numbers of some tetracycline resistance genes (tetPB, tetW, otrA, tetT, tetO) and class 1 integron-integrase gene.

Effects on development and microbial community of shrimp Litopenaeus vannamei larvae with probiotics treatment

Shrimp production is the second ranked of the most-traded production in these decades and the whiteleg shrimp Litopenaeus vannamei is the sixth most cultured species. Probiotics are alternative strategy for the promotion of growth and prevention of diseases in aquaculture. To confirm the effects of the probiotics on development and microbial community of L. vannamei larvae during different development stages, five kinds of probiotics (10⁸ ~ 10⁹ CFU/g) were added into the rearing environment of shrimp larvae, and the effects of probiotics on bacterial community and water quality, larval growth and immune index were determined from nauplius larval stage to post larval stage. Results suggested that probiotics treated groups showed larger survival rate than the control groups from Z1 stage to P5 stage. Lactobacillus could improve the larvae's survival ability, especially in the larval stages M2, M3, P1, P5 stage. It was confirmed that probiotics could promote the growth and development of shrimp larvae and prevent the incomplete molting in their growing process, particularly for EM-treated group. Results suggested that all the probiotics-treated groups had shown significant decreasing trend in the quantity of vibrios, except for the SA-treated group. And different probiotics could inhibit vibrios during different life periods. Among these probiotics, LA, EM and PB had shown the best effects, including improving survival rate of the larvae, promoting the larval metamorphosis, reducing the quantity of vibrios and NH₄-N and NO₂-N levels, and increasing bacterial diversity.

Reduction of spermatophore melanization in Litopenaeus vannamei shrimp fed Ulva clathrata during a commercial hatchery production

Male broodstock (Litopenaeus vannamei, 36 ± 7 g, n = 600) reproductive performance, spermatophores and reproductive tract melanization, prostaglandin concentrations and biochemical composition were evaluated after including 3.8% Ulva clathrata meal in the diet (dry base) of a commercial hatchery during 45 days. Males fed Ulva had less melanized spermatophores (120 compared with 233, P < 0.01), less bacteria in the ductus deferens (P < 0.01), more sperm cells in testicles (P < 0.05), and increased courtship activity (839 compared with 689, P < 0.01), with no effect on mortality. Ulva-fed males had more arachidonic acid (20:4n-6) in the spermatophores (P < 0.05) but this did not affect the prostaglandin concentrations in response to diet. Males fed Ulva had more carotenoids in the hepatopancreas (0.08 ± 0.02 compared with 0.01 ± 0.01 mg/g, P < 0.05), and phenolic compounds in hepatopancreas (6.1 ± 0.7 compared with 1.8 ± 0.7 mg eq. phloroglucinol/g, P < 0.05) and muscle (0.4 ± 0.3 compared with 0.2 ± 0.1 mg eq. phloroglucinol/g, P < 0.05). Males fed the Ulva also had a lesser carbohydrate content in the hepatopancreas (P < 0.01) and muscle (P < 0.01). In conclusion, supplementing fresh maturation diets with a small dose of dried Ulva allowed for improvement of reproductive performance and to decrease melanization in spermatophores and the male reproductive tract.

Antiviral activity of cathelicidin 5, a peptide from Alligator sinensis, against WSSV in caridean shrimp Exopalaemon modestus

White spot disease caused by white spot syndrome virus (WSSV) is responsible for harming shrimp aquaculture industry and results in a pandemic throughout the world. Cathelicidin 5 treatment enhanced immune parameters including antioxidant enzyme activity and immune-related genes expression in shrimp Exopalaemon modestus. Shrimp treated with cathelicidin 5 and inoculated with white spot syndrome virus (WSSV) exhibited a significantly lower mortality rate and lower viral VP28 amplification and expression than control. This study addresses the role of cathelicidin 5 in immune stimulatory and antiviral activities that could protect E. modestus from WSSV infection.

Survival and immune response of white shrimp Litopenaeus vannamei following single and concurrent infections with WSSV and Vibrio parahaemolyticus

The survival and immune responses of Litopenaeus vannamei were evaluated during white spot syndrome virus (WSSV) or Vibrio parahaemolyticus single and concurrent infections. The mortality, WSSV load, activities of 4 immune enzymes: acid phosphatase (ACP), alkaline phosphatase (AKP), peroxidase (POD) and superoxide dismutase (SOD), and the transcription of Evolutionarily Conserved Signaling Intermediate in Toll pathways of L.vannamei (LvECSIT) were quantified at 0, 3, 6, 12, 24, 48, 72 and 96 h post-infection (pi). The results showed: (i) the cumulative mortality of the co-infection group (WSSV and V. Parahaemolyticus 83%) was significantly lower than the WSSV infection group (97%) (P < 0.05) at 96 hpi; (ii) copies of WSSV in the co-infection group were significantly lower than that of the single infection group from 24 to 96 hpi (P < 0.05); (iii) ACP, AKP,POD and SOD activity in the gills of the co-infection group was higher than that of the WSSV group at12, 48 and 96 hpi (P < 0.05).The expression of LvECSIT mRNA in the co-infection group was significantly higher than in the WSSV infection group from 12 to 72 hpi (P < 0.05).The results indicate that proliferation of WSSV is inhibited by V.parahaemolyticus infection. In addition, infection with WSSV alone causes a significant reduction in some immune responses of shrimp than co-infection with WSSV and V.parahaemolyticus occurs at 26 °C. Third, LvECSIT, an essential member of TLR signaling pathway might play a crucial role in shrimp defense against WSSV - Vibrio co-infection.

An effective white spot syndrome virus challenge test for cultured shrimp using different biomass of the infected papilla

White spot syndrome virus (WSSV) is one of the most virulent pathogens of cultured penaeid shrimp. Several control strategies are used commonly to mitigate the economic losses caused by the pathogen, such as application of antiviral products at farm level. One of the most practical method for the screening of potential anti-WSSV products is through challenge tests. Therefore, it is essential to develop simple, reproducible and effective bioassays able to simulate specific mortality levels. The purpose of this study was to develop a simple and reproducible bioassay that simulate different mortality levels by varying the proportion of WSSV-infected and noninfected shrimp tissues administered to susceptible shrimp during a per os challenge test. This method mimics one of the natural transmission routes of WSSV infection in shrimp and could be applied to identify potential antiviral products to different cultured shrimp species susceptible to WSSV. Here we report: •A simple and economic method to evaluate therapeutic antiviral products against WSSV through a challenge test, that uses different biomass amounts of WSSV-infected papilla.•Allows to simulate a wide and reproducible range of mortalities observed in shrimp farms.•A challenge test that simulates one mode of natural WSSV infection in shrimp.

Response of hemocytes profile in the black tiger shrimp (Penaeus monodon) against Vibrio harveyi induced by Xylocarpus granatum leaves extract

Aim:

The present study investigated hemocytes profile of black tiger shrimp (Penaeus monodon) induced with Xylocarpus granatum leaves extract to protect against Vibrio harveyi infection.

Materials and Methods:

X. granatum leaves were chopped into small size, air-dried, and extracted with one of the following solvents: Ethanol, distilled water, and seawater, whereas each solvent was given in three different concentrations (750 ppm, 1.000 ppm, and 1.250 ppm, respectively). Extracts were induced to 60 post-larvae shrimp in each treatment (three replicates, 20 shrimp for each) by immersing method and subsequently challenged with V. harveyi.

Results:

This study demonstrated different effectiveness among solvents used to extract X. granatum leaves, in which distilled water showed the most effective solvent as can be seen from the lowest percentage on anorexia, lethargic, and weakened reflex of shrimp compared with another solvent, positive and negative controls. Pathological symptoms for shrimp induced by X. granatum leaves extract were minimum with the highest survival rate compared with those of positive and negative control. Total hemocyte cells and its cell constituents such as semi-granular, granular, and hyaline cells on treatment group at 1.250 ppm were higher than controls.

Conclusion:

Leaves extract of X. granatum extract effectively inhibited V. harveyi infection, increased survival rate, and hemocytes cell of the experimental shrimp. Distilled water extract of X. granatum at 1.250 ppm demonstrated the highest protective effect toward V. harveyi infection on P. monodon.

Microalgae species as potential inhibitors of the bioactivity of Vibrio parahaemolyticus in shrimps

Vibrio parahaemolyticus is a Gram-negative motile bacteria belonging to Vibrionaceae family causing cytotoxicity in cultured cells and enterotoxicity in animal models. Similarly, this bacterium is a major foodborne pathogen that causes life-threatening diseases in human, including gastroenteritis and septicemia, via consumption of contaminated seafood. Based on the increasing interest in developing novel environmental friendly solutions for the inhibition of the bioactivity of V. parahaemolyticus, microalgae species have emerged as potential candidates due to the microbiota associated with microalgae cultures, oxygen radicals produced during the photosynthetic process and the production of secondary metabolites, useful for antibacterial properties. In the present review, conventional treatments concerning V. parahaemolyticus bioactivity have been presented. However, in terms of effectiveness, numerous studies explaining the use of microalgae species for antibacterial activity against V. parahaemolyticus have been detailed suggesting that microalgae-based treatment are considerably better. Finally, we presented a proposed microalgae-based solution that can act as an inhibitor of V. parahaemolyticus bioactivity and therefore can be applied in the aquaculture industrial field to improve productivity and reduce costs.