Probiont niche specialization contributes to additive protection against V ibrio owensii in spiny lobster larvae

Abstract

Summary

The development of efficient probiotic application protocols for use in marine larviculture relies on comprehensive understanding of pathogen–probiont–host interactions. The probiont combination of P seudoalteromonas sp. PP 107 and V ibrio sp. PP 05 provides additive protection against vectored V ibrio owensii DY 05 infection in larvae (phyllosomas) of ornate spiny lobster, P anulirus ornatus . Here, fluorescently tagged strains were used to demonstrate niche specialization of these probionts in both the live feed vector organism A rtemia and in phyllosomas. The pathogen was vulnerable to direct interaction with PP 05 in the bacterioplankton as well as in the A rtemia gut and the phyllosoma foregut and midgut gland. In contrast, PP 107 was localized on external surfaces of A rtemia and phyllosomas, and direct interaction with the pathogen was limited to the bacterioplankton. While PP 107 was the overall dominant ectobiont on the phyllosoma cephalothorax and inner leg segments, PP 05 was the primary colonizer of outer leg segments, nutrient‐rich locales that may promote ingestion during feeding. This study shows that niche specialization can contribute to the additive probiotic effect of a probiotic mixture and highlights that probiotic enrichment of A rtemia cultures can intercept the infection cycle of V . owensii DY 05 in early‐stage P . ornatus phyllosomas.