Cultivation of the red seaweed Kappaphycus alvarezii with effluents from shrimp cultivation and brown seaweed extract: Effects on growth and secondary metabolism.

The growth and metabolic profile of the red seaweed Kappaphycus alvarezii were evaluated after in vitro cultivation with effluents from Pacific shrimp Litopenaeus vannamei farming in bioflocs system (BFT) and commercial extract of the brown seaweed Ascophyllum nodosum (AMPEP). Seaweeds were cultivated for 35 days in sterilized seawater enriched with 50% von Stosch solution (VS – v/v), 25% BFT effluent (BFT – v/v), or pulse-fed AMPEP (at 0.1 g L − 1 for 30 min), and combinations of VS and AMPEP (VS + AMPEP) and BFT and AMPEP (BFT + AMPEP). As control, seedlings cultivated in sterilized seawater were used. K. alvarezii from VS and BFT showed significant higher growth rates, i.e., 1.70 ± 0.14% day − 1 and 1.56 ± 0.08% day − 1 , respectively, while control (0.51 ± 0.05% day − 1 ) and AMPEP (0.57% ± 0.07% day − 1 ) showed lower growth rates. However, in all treatments, "ice-ice" disease was observed in some parts of the thalli. Total phenolic content (92.2 ± 22.4 μg g − 1 ) and flavonoids (18.8 ± 0.6 μg g − 1 ) were higher in BFT, and seedlings cultivated in BFT + AMPEP showed higher carotenoid content (239.3 ± 9.3 μg g − 1 ). Higher DPPH radical inhibition was observed in VS (13.4 ± 1.5%) and VS + AMPEP (13.4 ± 0.6%). Results showed that all treatments affected K. alvarezii growth and secondary metabolism, particularly BFT, which could be consider as a good fertilizer of this species improving also the add-value, because of the increase of phenolics, flavonoids and carotenoids. Statement of relevance This work presents the potential use of effluents from shrimp cultivation as fertilizers of the Kappaphycus alvarezii , improving the growth and the bioactive compounds production. [ABSTRACT FROM AUTHOR]