Shrimp lectin–conjugated copper sulfide nanoparticles enhance immune response and gene expression in Etroplus suratensis infected with Aeromonas hydrophila

Aquaculture International - Lectins are hemagglutinating glycoproteins which act as pathogen recognition receptors that can bind to the pathogen-associated molecular patterns. Shrimp lectin...     

Green fluorescent protein visualization of Vibrio parahaemolyticus infections in Indian white shrimp Fenneropenaeus indicus (H Milne Edwards)

The pathways by which pathogens invade Fenneropenaeus indicus, the potential colonization in various tissues and the disease transmission mechanisms are unclear. The aims of the present study were to visualize the colonization and pathogenesis of GFP‐tagged Vibrio parahaemolyticus, in various tissues of F. indicus to evaluate the pathogen interaction. Among the three strains isolated, a virulent strain VpDAHV2 was tagged with green fluorescent protein (GFP‐VpDAHV2) and validated for both its growth characteristics and its virulence as a genuine model for F. indicus infection. VpDAHV2 was positive for toxR and tlh genes and negative for tdh genes. CLSM images revealed that maximum colonization was observed in the haemolymph of the F. indicus challenged with GFP‐VpDAHV2. The haemolymph was the primary site for the colonization of GFP‐VpDAHV2 in F. indicus. The enteric localization occurred independently of the flagellum or motility of GFP‐VpDAHV2 through the intestinal route. The F. indicus infection model suggests that the haemolymph and the intestine represent the sites of infection by GFP‐VpDAHV2, and hence are the active sites of pathogen interactions. GFP tagging of V. parahaemolyticus is a new and systemic approach to determine the presence of bacteria in vivo for the confirmation of host pathogen interactions in aquaculture studies.     

Antibacterial activity of Allium sativum against multidrug-resistant Vibrioharveyi isolated from black gill–diseased Fenneropenaeus indicus

The present study evaluated the in vitro and in vivo inhibitory effects of Allium sativum extracts against the multidrug-resistant Vibrio harveyi, isolated from the black gill–diseased Fenneropenaeus indicus. Initially, the antibiogram of pathogenic V. harveyi was documented for its resistance towards selected commercial antibiotics. Further, antibacterial activity of A. sativum against Vibrio harveyi was performed by the agar well diffusion method. V. harveyi culture was seeded over the agar plates, and each of the garlic extracts (freshly squeezed garlic extract—FSGE, freeze-dried garlic extract—FDGE and methanolic garlic extract—MGE) was tested at three different concentrations. FSGE showed greater inhibitory activity against V. harveyi than FDGE and MGE. Three diets of standard meal preparation for shrimp containing 0% garlic as a control, 0.5% garlic and 1% garlic treatments were formulated to evaluate the effects of garlic on the experimental infection of shrimp with V. harveyi. The combined results of long- and short-term garlic (1%) extract treatment showed a 75% reduction in cumulative mortality. The present study discusses the advantages of using freshly squeezed garlic extract treatment in shrimp culture that could offer a promising alternative to the use of antibiotics in aquaculture to control disease.     

Inhibitory effects of Bacillus licheniformis (DAB1) and Pseudomonas aeruginosa (DAP1) against Vibrio parahaemolyticus isolated from Fenneropenaeus indicus

In aquaculture industries, there is an urgent need to develop microbial control strategies, to control disease outbreaks. In recent years, probiotics are considered as a valid alternative for the use of antibiotics in aquaculture to prevent high mortality and promote growth. In the present study, seven strains of bacteria such as Bacillus licheniformis (DAB1), Bacillus pumilus (DAB2), Bacillus sp. (DAB3), Pseudomonas aeruginosa (DAP1), Pseudomonas sp. (DAP2), Pseudomonas aeruginosa (DAP3), Pseudomonas aeruginosa (DAP4), and three pathogenic Vibrio parahaemolyticus (DAV1, DAV2, DAV3) were isolated from healthy and diseased Fenneropenaeus indicus collected from the east coast of Tamilnadu, India. The strains were identified by biochemical analysis and 16S rRNA sequence methods. Among the seven probiotic strains tested, the cell-free extract from DAB1 and DAP1 exhibited higher inhibitory activity of V. parahaemolyticus than other isolates under in vitro conditions. The LC₅₀ of DAV1, DAV2, and DAV3 was found to be ～10³ CFU mL^?1. Pathogenicity of three V. parahaemolyticus DAV1, DAV2, and DAV3 showed significant mortalities (40 %) in Artemia nauplii at inoculation densities of 10³ CFU mL^?1 when compared to the controls (unchallenged nauplii). A significant reduction in mortality (P < 0.001) was found by addition of 10⁶ CFU mL^?1 of DAB1 and DAP1 strains in nauplii against the pathogens. In conclusion, the present study result reveals that DAB1 and DAP1 have potential applications for controlling pathogenic V. parahaemolyticus in Artemia culture systems and aquaculture practices.     

Inhibitory activity of essential oils from medicinal plants against Pseudomonas sp. isolated from aquatic environments

This study focuses on the evaluation of the antimicrobial activity of essential oils (EOs) from medicinal plants against Pseudomonas sp isolated from aquatic environments, and proves its controlling efficacy on Pseudomonas aeruginosa‐Dahp1 using Confocal Laser scanning Microscopy. Twenty‐seven Pseudomonas spp. (Ps ₁–Ps ₂₇) were isolated using King's B medium and the selected P. aeruginosa‐Dahp1 was confirmed using 16S r‐DNA methods. Antimicrobial activity of 10 EOs was determined using agar well and disc diffusion methods. Ten EOs were extracted with six solvents and the crude extracts were tested against the Pseudomonas spp. through disc diffusion method. Among 10 EOs tested, maximum inhibitory activity was noted in EOs of Wringtia tinctoria against the P. aeruginosa‐Dahp1 in the disc diffusion method. The MIC values (concentrations were expressed in Weight/Volume) of the EOs range from 0.5 to 9.054 mg mL^?1. The EO of W. tinctoria showed the maximum activity at the concentration (w/v) of 2.060 mg mL^?1. The EO of W. tinctoria with chloroform extract showed the maximum inhibition against P. aeruginosa‐Dahp1. The CLSM proves the control and viability of 1 × 10⁵ CFU mL^?1 of P. aeruginosa‐Dahp1 at a lower concentration (2.720 mg) of EOs with chloroform extracts of W. tinctoria. This study pivots for designing of new drugs using EOs of W. tinctoria against Pseudomonades in the aquaculture sites.     

Medicinal plant derivatives as immunostimulants: an alternative to chemotherapeutics and antibiotics in aquaculture

Aquaculture makes a significant contribution in the production of protein-rich food for human consumption. Aquaculture practices encounter many challenges, and one of the most devastating problems is disease outbreaks caused by microbial pathogens. To control disease outbreaks, several chemotherapeutics and antibiotics were used indiscriminately, which in turn leads to residual problems in the surrounding environment affecting higher animals and also humans. Immunostimulants are considered as an alternative for antibiotics, which will boost the immune system of the cultured organism, thus effectively countering the assault of pathogens. The use of plant materials as immunostimulant will be an ecofriendly approach for the control of pathogens. The botanicals present in the plants have a key role in enhancing the fish immunity. This review focuses on the importance of plant material as immunostimulant in the control of diseases in aquaculture.     

Molecular markers and their application in genetic diversity of penaeid shrimp

Penaeidae is a family of shrimp, and it contains many species of economic importance, such as the tiger prawn (Penaeus monodon), white leg shrimp, Atlantic white shrimp and Indian prawn. Identification and population genotype structure of penaeid shrimp have been enhanced by molecular markers that can be classified into three types, namely allozyme, mitochondrial and nuclear markers. The widely used mitochondrial DNA markers are 12S rDNA, 16S rDNA, cytochrome b and control region. Random amplification of polymorphic DNA, amplified fragment length polymorphism, restriction fragment length polymorphism, single-stranded conformational polymorphism and microsatellites are the most commonly used nuclear markers for DNA fingerprinting. Molecular markers play a crucial role in penaeid shrimp to evaluate phenotypic and genetic variation, assess demographic bottleneck, study natural population structure, compare wild and hatchery populations, preserve genetic biodiversity, construct chromosome maps and detect whether genetic tag propagation–assisted rehabilitation programs are effective. Increase in the number of molecular markers, construction of high-density genetic maps and implementation of genomic resources (including genome sequencing) are expected to provide tools for the genetic improvement in these aquaculture species through marker-assisted selection. Molecular markers are versatile tools for the identification of populations with genetic crisis by comparing genetic diversities, which helps to establish management units within these threatened species.     

Phytotherapy and combined nanoformulations as a promising disease management in aquaculture: a review

Aquaculture International - Aquaculture-based foods have enriched nutritional and medicinal value to meet the needs of the global population. Recently, improper maintenance of aquatic organisms in...