Bioremediation in marine aquaculture: Halophyte-bacteria interaction for enhanced nutrient removal

This study tests the hypothesis that inoculating the halophyte Salicornia europaea with plant growth-promoting bacteria (PGPB) enhances nutrient extraction and biomass production in saline aquaponic systems. Using two strains, Brevibacterium casei EB3 and Pseudomonas oryzihabitans RL18, we evaluated their effects on plant performance and microbial community dynamics under pot and pilot-scale tank conditions. Inoculation with RL18 alone significantly increased nitrogen accumulation in pot trials. At the same time, co-inoculation with EB3 and RL18 yielded the greatest improvements in tank systems, including a 1.7-fold increase in nitrogen extraction and a threefold rise in biomass. Elemental analysis revealed enhanced uptake of B, Ca, Cu, and Mg in inoculated plants, supporting improved physiological performance. DGGE fingerprinting combined with dendrogram analysis, Bray-Curtis dissimilarity matrices, and multivariate statistics (PERMANOVA, PCA) demonstrated significant shifts in the root-associated microbial community due to inoculation and system type. These results highlight strain-specific and context-dependent responses, reinforcing the need for tailored microbial strategies in integrated multi-trophic aquaculture (IMTA). This work contributes to optimizing microbial-assisted phytoremediation in saline aquaponics by elucidating both physiological and ecological mechanisms.