The effect of β-1,3-glucan derived from Euglena gracilis (Algamune™ ) on the innate immunological responses of Nile tilapia (Oreochromis niloticus L.).

Abstract

Algamune™ is a commercial additive produced from Euglena gracilis, providing a rich source of the β-1,3-glucan paramylon. Isolated kidney phagocytes of Nile tilapia were incubated with graded doses (0, 8, 16, 32, 64 and 128μg/ml) of Algamune™ and purified paramylon to gauge their ability to elicit the production of reactive oxygen species. A linear response was observed for extracellular superoxide anion for both sources but only Algamune™ for intracellular superoxide anion. After corroborating the immunostimulant properties exvivo, a feeding trial was conducted to evaluate the dietary supplementation of Algamune™ (0, 100, 200, 400 and 800mg/kg of diet) for Nile tilapia. Fish were fed for 3weeks, after which, fish were sampled for blood and head kidney phagocytes. The remaining fish were challenged with Streptococcus iniae. Macrophage extracellular superoxide anion production was significantly elevated in fish fed diets with 200mg of Algamune™ kg-1 when compared to fish fed the basal diet. Even though the disease challenge did not show statistical differences, it is worth mentioning that fish fed intermediate doses of Algamune™ had lowest numerical mortality values. Therefore, Algamune™ was demonstrated to enhance some immunological responses of tilapia both in exvivo and invivo.