There is an urgent need in aquaculture to develop microbial control strategies, since disease outbreaks are recognized as important constraints to aquaculture production and trade and since the development of antibiotic resistance has become a matter of growing concern. One of the alternatives to antimicrobials in disease control could be the use of probiotic bacteria as microbial control agents. This review describes the state of the art of probiotic research in the culture of fish, crustaceans, mollusks, and live food, with an evaluation of the results obtained so far. A new definition of probiotics, also applicable to aquatic environments, is proposed, and a detailed description is given of their possible modes of action, i.e., production of compounds that are inhibitory toward pathogens, competition with harmful microorganisms for nutrients and energy, competition with deleterious species for adhesion sites, enhancement of the immune response of the animal, improvement of water quality, and interaction with phytoplankton. A rationale is proposed for the multistep and multidisciplinary process required for the development of effective and safe probiotics for commercial application in aquaculture. Finally, directions for further research are discussed.

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Probiotic Bacteria as Biological Control Agents in Aquaculture

http://mydez.persiangig.com/pdf/The%20use%20of%20probiotics%20in%20aquaculture.pdf

The use of probiotics in aquaculture

The role of probiotics in aquaculture

Probiotics and immunity: a fish perspective.

In performing phenotypic characterization tests, the organisms used for the inoculation of test media should be from fresh transfers and in good physiological condition. The methods described in this chapter are based primarily on methods developed for the characterization and identification of organisms which have usually been isolated on nutrient-rich media. While zoologists may be content to classify all insects or all vertebrates, prokaryote systematics generally deals with all prokaryotes and in an evolutionary context attempts to extend this study back to the origin of life itself. To test for acetamide hydrolysis, streak the surface of an acetamide agar slant with a sample from a dilute suspension. Incubate for up to 7 days. Care should be taken to ensure that the basal medium to which the carbohydrates are added does not contain fermentable or oxidizable sugars, and control media without any added carbohydrates should always be included during testing of cultures. Methanogenic members of the Archaea also fluoresce under UV light. Some facultative anaerobes, such as Escherichia coli and Staphylococcus aureus, grow aerobically by respiration with oxygen and grow anaerobically by fermentation.

Phenotypic Characterization and the Principles of Comparative Systematics

http://www.ssu.ac.ir/fileadmin/templates/fa/daneshkadaha/daneshkadah_pezeshki/goroha/rhienonogy/probiotics/artigo2.pdf

Probiotics in aquaculture: The need, principles and mechanisms of action and screening processes

Probiotic activity of Aeromonas media on the Pacific oyster, Crassostrea gigas, when challenged with Vibrio tubiashii

Bacterial pathogens of Greenshell mussel (GSM) larvae can cause batch losses during hatchery production. Twenty-two isolates were screened using a larval bioassay. Two strains were identified as potential pathogens. Phenotypic identification of these strains revealed two non-reactive Gram-negative, oxidase positive rods. Sequencing of the 16S rRNA gene identified Vibrio splendidus and a V. coralliilyticus/neptunius-like isolate as pathogens of GSM larvae, with an ability to cause 83% and 75% larval mortality in vitro, respectively, at a concentration of 10(2) CFU mL(-1). Histopathology indicated that the route of infection was via the digestive system. Using healthy larvae as target hosts, Koch's postulates were confirmed for the two isolates. This is the first report on pathogens of GSM larvae.

Two pathogens of Greenshell mussel larvae, Perna canaliculus: Vibrio splendidus and a V. coralliilyticus/neptunius-like isolate.

Control of saprolegniosis in the eel Anguilla australis Richardson, by Aeromonas media strain A199

A bacteriocin-like inhibitory substance (BLIS) produced by Aeromonas media strain A199 inhibited the growth of Saprolegnia sp. in vitro, an opportunistic pathogen isolated from affected eels, Anguilla australis (Richardson). The presence of BLIS in solid media inhibited the growth of the vegetative state of the aquatic mould as well as the germination of cysts. Uninhibited growth was, however, observed in the presence of inactive BLIS, suggesting that the in vitro antagonism derived from the BLIS of A199. In four independent in vivo tank observations of fish affected with saprolegniosis, the daily addition of A199 to tank water contributed to the subsequent swift recovery of affected hosts from invasion by this opportunistic pathogen.

L.F. Gibson

Papers

Probiotics in aquaculture: The need, principles and mechanisms of action and screening processes

Probiotic activity of Aeromonas media on the Pacific oyster, Crassostrea gigas, when challenged with Vibrio tubiashii

Two pathogens of Greenshell mussel larvae, Perna canaliculus: Vibrio splendidus and a V. coralliilyticus/neptunius-like isolate.

Control of saprolegniosis in the eel Anguilla australis Richardson, by Aeromonas media strain A199

Antagonistic activity of Aeromonas media strain A199 against Saprolegnia sp., an opportunistic pathogen of the eel, Anguilla australis Richardson