Marine Lactobacillus pentosus H16 protects Artemia franciscana from Vibrio alginolyticus pathogenic effects

Abstract

Vibrio alginolyticus is an opportunistic pathogen which may affect different aquatic organisms. The aim of this study was to assess the probiotic properties and the protective mode of action of Lactobacillus pentosus H16 against V. alginolyticus 03/8525, through in vitro and in vivo studies using Artemia franciscana. This strain showed antimicrobial activity against V. alginolyticus 03/8525 and Aeromonas salmonicida subsp. salmonicida ATCC33658 possibly related with lactobacilli organic acid production. It was able to survive at high rainbow trout bile concentrations and showed high selective adhesion to rainbow trout mucus (1.2 E+05 ± 8.0 E+03 cells/cm2). H16 outcompeted with V. alginolyticus 03/8525 and A. salmonicida subsp. salmonicida ATCC33658, greatly reducing their adherence to rainbow trout mucus (64.8 and 74.1%, respectively). Moreover, H16 produced a cell-bound biosurfactant which caused an important diminution of the surface tension. H16 also protected Artemia nauplii against mortality when it was administered previously to V. alginolyticus 03/8525 inoculation. Furthermore, H16 bioencapsulated in Artemia suggesting that it is possible to use live carriers in its administration. We conclude that the capability of L. pentosus H16 to selectively adheres to mucosal surfaces and produces cell-bound biosurfactants, displacing pathogenic strains, in addition to its antimicrobial activity, confer H16 competitive advantages against pathogens as demonstrated in vivo challenge experiments. Thus, L. pentosus H16, a marine bacterium from the intestinal tract of hake, is an interesting probiotic for Artemia culture and has also potential in the prevention of vibriosis in other aquaculture activities such as larvae culture and fish farming.