Researchers Find Potential for Probiotic in Aquaculture Sector

The use of probiotics in marine aquaculture, as in the case of Senegalese sole, is still in its experimental stage.

Jul 19 2011 --- IEO researchers have demonstrated the benefits of the inclusion of the probiotic Pdp11 Shewanella putrefaciens in the diet of Senegalese sole, which bestow resistance against pasteurellosis, one of the most serious diseases, responsible for significant economic losses in Spanish aquaculture sector, that has led to the closure of many companies in the Mediterranean area.

Researchers at the Spanish Institute of Oceanography (IEO), in collaboration with the universities of Cantabria (UC) and Malaga (UMA) and the Center for Marine Research of Pontevedra (CIMA), just published in the journal Aquaculture Research a study about the influence of the probiotic Pdp11 in growth, body composition and resistance to pseudotuberculosis of the Senegalese sole (Solea senegalensis).

The use of this probiotic, whose specific name is Shewanella putrefaciens, improves significantly the survival against Photobacterium damselae subsp. piscicida (pateurelosis responsible bacteria). In addition, it promotes animal welfare, improves the condition of the fishes, and protects them against the stress of intensive cultivation.

In aquaculture, probiotic means all microbial cells, alive or dead, or even a cellular component, which bestows benefits to the host when is supplied.

For the study, three groups of sole juveniles were used and they were fed with three diets: the first supplemented with fresh probiotic, the second with lyophilized probiotic and the third, the control group, with a standard diet.

The study showed that both probiotic diets significantly improve the survival of the sole copies against to an experimental infection with the bacterium that causes the pseudotuberculosis. In the case of fresh probiotic, the relative survival rates reached 44%.

Regarding the effect on growth, the group fed with fresh probiotic reached higher rates than those fed with standard diet. This effect was not recorded with the lyophilized probiotic.

Also, no significant differences in body composition of muscle were recorded among the different groups. Total percentage of protein, lipid and fatty acid profile showed similar levels in all three groups.

Right now the Senegalese sole is not a consolidated species at an industrial level in aquaculture. This is mainly due to the high incidence of diseases during the fattening stage. The current intensive production systems generate stress in culture specimens, resulting in a lower digestive efficiency, increasing the susceptibility to pathogens and potentiating economic losses in the industry.

Pseudotuberculosis, also known as pasteurellosis, whose appearance is associated with high summer water temperatures of cultivation, is a disease caused by the bacterium Photobacterium damselae subsp. piscicida. This organism, highly infectious, is responsible for the highest mortalities recorded in Spanish aquaculture.

Aquaculture production depends largely on the physiological state of the fishes. To achieve this, is necessary to develop specific commercial feed and management protocol that promote animal welfare and reduce the incidence of infections.

The traditional use of antibiotics in aquaculture has led to the emergence of resistant bacteria. In addition, these types of treatment practices involve a risk for human and environment health.

The use of probiotics in diet has considerably developed over the last 20 years, both as components of dairy products or as part of mixed drinks and infant feeding. Also, probiotics are commonly used in livestock with great success.

Recently, probiotics was being used in salmon culture, and it seems an effective tool for improving the metabolism, reducing deformity and preventing diseases. However, the use of probiotics in marine aquaculture, as in the case of Senegalese sole, is still in its experimental stage.