Too young for drugs - Artemia flavoured Yakult for the little ones

Bacterial diseases are a major problem of marine aquaculture. High mortality of marine fish larvae especially, has been frequently attributed to Vibrio infections (esp. Vibrio alginolyticus). The excessive use of antibiotics in the past has led to spreading of resistant strains, and other techniques such as vaccination are not suitable for larval phases. There is therefore a need to find new methods to tackle the problem of diseases. Probiotics are microbial cells provided via the diet or rearing water that benefits the host condition improving the microbial balance of the organism and the resistance to diseases. It might be an interesting alternative to traditional administrations of antibiotics, especially for the more sensitive larvae phase.

Strains of the lactic acid bacteria (LAB) were previously used as effective probiotics in, carps, eel, sea bass, and rainbow trout. Surprisingly most studies using LABs as aquaculture probiotics have employed non-marine strains, although marine strains may actually present the advantage of being adapted to salinity and therefore be able to compete with pathogenic strains in euryaline fish farming and mariculture.  Garcés et al. (2015) assessed the probiotic properties and the protective mode of action of the marine strain Lactobacillus pentosus H16 against V. alginolyticus 03/8525 on Artemia franciscana. Artemia are commonly used as live feeds in fish and crustacean larvae aquaculture and are also important aquatic models to study host-microbial interactions.

The strain L. pentosus H16 was isolated from the intestinal tract of hake (Merluccius hubbsi) collected of the coast of Argentina. Tests of antimicrobial activity indicated that L. pentosus H16 selectively adheres to mucosal surfaces displacing pathogenic strains such as Vibrio alginolyticus 03/8525 and Aeromonas salmonicida subsp. salmonicida ATCC 33658. In addition to its antimicrobial activity, L. pentosus H16 was shown to produce cell-bound bio surfactants, confirming H16`s competitive advantages against pathogens.

Probiotic capability of H16 when bioencapsulated in Artemia was testes in vivo, and experiments confirmed that H16 protects Artemia nauplii of mortality caused by V. alginolyticus 03/8525. These findings suggest that it is possible to use live carriers in H16 administration, for example to prevent infections at larval phases – an interesting but scarcely explored alternative to administer probiotics.

According to this study, L. pentosus H16 is a promising probiotic for Artemia culture and has also the potential for other aquaculture activities such as larvae culture and fish farming. For further research I would suggest investigating of how effective encapsulated H16 in Artemia is when fed to organisms. It would be interesting to know if whether it is the healthier food, or the probiotic itself that could enhance larvae survival of farmed animals.

Garcés ME, Sequeiros C, Olivera NL (2015) Marine Lactobacillus pentosus H16 protects Artemia franciscana from Vibrio alginolyticus pathogenic effects. Diseases of Aquatic Organisms 113: 41–50