Peter de Schryver is this year’s recipient of the Jules Tournut Probiotics Prize. Awarded at the trade show EuroTier, the prize recognized his work in evaluating a new microbial-based approach to improve aquaculture practices.

His study looked at applying poly-B-hydroxybutyrate, or PHB, as a feed supplement in aquaculture. At levels of 2 percent and 5 percent in the diet, PHB seemed to significantly enhance the growth performance of juvenile European sea bass with a factor of 2.4 and 2.7, respectively. The richness and genetic diversity of the intestinal microbial community in terms of the range-weighted richness seemed to be closely correlated with the growth performance of the fish, suggesting a host-microbial interaction that was steered by the presence of PHB.


Supplementation with PHB had a steering effect in juvenile sea bass, resulting in converging microbial community similarities between treated fish. PHB induced more equal abundances between the various bacterial species, and higher PHB levels resulted in a higher degree of evenness.

To increase the efficiency of PHB treatment, PHB depolymerising probiotics were isolated for the first time from the intestinal environment of juvenile sea bass, sturgeon and giant river prawns. These were combined with PHB in a symbiotic strategy. This approach increased the survival of Artemia franciscana nauplii with a factor of 2 to 3 when challenged with a pathogenic Vibrio strain, compared to an approach with PHB or the isolates alone.