Edible fungi pellets as an effective carrier of microalgae biomass and fish waste hydrolysates

Abstract

Microalgae are a promising resource for food and feed, but their large-scale application is limited by the high cost of biomass harvesting. Fungal-assisted bioflocculation offers a sustainable alternative; however most reported fungal strains are inedible, limiting their use in food and feed applications. This study evaluates the efficiency of the edible fungi Pleurotus pulmonarius LBM105 and Lentinus sajor-caju LBM266 to flocculate four native microalgae strains from Misiones, Argentina. The effect of a sugarcane bagasse extract (SBE) based medium on flocculation efficiency (FE) and biomass composition was assessed. Results showed that P. pulmonarius LBM105 pellets obtained in malt extract (ME) medium achieved a FE of 96 % after 24 h when co-cultivated with G. emersonii CMI015. In contrast, L. sajor-caju LBM266 pellets exhibited a lower FE (65–71 %) in the standard medium but reached 100 % in SBE medium when co-cultivated with CMI015 and CMI016. ATR-FTIR analysis suggested the involvement of amino, amide, phosphate, hydroxyl, and carboxyl groups in fungal–microalgal interactions. Biomass characterization of the fungal-microalgae pellets (FMP) revealed compositional shifts with increased lipid and protein content in P. pulmonarius LBM105 + CMI015 pellets. FMPs were further enriched with fish waste hydrolysate (FWH). In lyophilized P. pulmonarius + CMI015 pellets, FWH supplementation increased both lipid, protein and total phenolic content (TPC) levels, while in L. sajor-caju + CMI016 only TPC increases. This strategy of FWH enrichment using lyophilized FMPs as carriers represents a sustainable method for incorporating bioactive compounds into biomass. These findings highlight the potential of FWH-enriched fungal–microalgae pellets for use in food and feed applications.