The use of probiotic in aquaculture: an overview

This review encompasses many points which need to be considered when looking into the use of probiotics within aquaculture.

Aquaculture is a huge industry, which in this paper is said to have been expanding at a rate of 9.2% per year since 1970, compared to a 2.8% growth from terrestrial-farmed meat. The most profitable farmed organisms within aquaculture are shrimp. However, with the increase in aquaculture, problems occur which are often difficult to control, such as the increased spreading of diseases. In previous years, antibiotics have been used to control the disease outbreaks. However, the USA and the European Union have restricted the use of antibiotics as they found that they accumulated in fish products and could be harmful to humans. The new restriction has forwarded research in the areas of probiotics, probiotics, phytobiotics and synbiotics as dietary supplements to promote health and growth.

The review summarises and evaluates the current knowledge of the use and action of the probiotic in aquaculture and its further potential.

Defining the probiotics in this review looks back at the first definition by Lilley and Stillwell in 1965; and how many studies have based their definitions around this original idea through the 90’s and into the 21^st century, finalising with a current definition by Gomez et al. in 2007. The authors continue to add their own input to the definition with a summary of all ‘the use of microorganism or their products (microbial cells element or cell free supernatant factors) to tanks and ponds in which animals live, as biological control or their capacity of modified the bacterial composition of aquatic animal’s intestine, water and sediment, or used with feed as health supplement and/or biological control.

The authors discuss how probiotics are selected in aquaculture, detailing that probiotics should have beneficial effects (antagonism to pathogens, ability to produce metabolites and enzymes, colonisation and adhesion properties and finally enhance the immune system) and cause no harm to the host.

Competitive exclusion is covered, explaining in the context of the fish gastrointestinal tract, how an established microflora prevents/ reduces the colonisation of competing bacterial species, which challenge for the same location, therefore giving an understanding of how the probiotics used in aquaculture are expected to change the gut microbiota.

The authors indicate that it is the non-specific immune response which is stimulated by probiotics and elucidate how the change in gastrointestinal microbiota is at the source of this. Furthering the readers understanding of how bacteria colonise the gut, the authors mention the adhesion abilities of the microbiota to the mucosa

The review is ended, by summarising the benefits and downfalls of probiotics and suggests some improvements to previous research and further study which may push the use of probiotics as a dietary supplement in aquaculture forward.

Lara-Flores, M., 2011. The use of probiotic in aquaculture: an overview. International Research Journal of Microbiology. 2 (12), 471-478.