Poly-β-hydroxybutyrate (PHB)-accumulating Halomonas improves the survival, growth, robustness and modifies the gut microbial composition of Litopenaeus vannamei postlarvae

Abstract

The PHB-accumulating Halomonas strain was isolated from local solar saltworks and was cultured in CM culture medium with addition of 30 g L−1 glucose to favor the PHB accumulation in the cells. The effect of Halomonas-PHB on the survival, growth, osmotic stress tolerance, resistance against Vibrio anguillarum challenge and the gut microbial composition of Litopenaeus vannamei postlarvae were investigated. The postlarvae PL6 were fed Artemia nauplii enriched with Halomonas-PHB (HM.PHB), Halomonas without PHB accumulation (HM), commercial PHB particles (par.PHB) and non-enriched Artemia nauplii (Control), respectively, for two weeks. The results revealed that both Halomonas-PHB and particle PHB could improve the survival, growth, and enhance the robustness of the shrimp PLs under both challenge and non-challenged conditions. High throughput sequencing on gut microbiota indicated that Halomonas-PHB not only suppressed the propagation of Vibrio, but also diverged to gut microbiota towards to the probiotic bacteria propagation (i.e. Bacillus and Lactobacillus) in the gut. In conclusion, the Halomonas-PHB is more efficient than particle PHB in L. vannamei larviculture and thus can be applied as feed additive in shrimp culture.