Subtleties of tetracycline removal during growth of microalgae-fungi consortia: Mechanistic insights from perspectives of extra- and intracellular metabolites

• Microalgae-fungi consortia removed 85.56–93.00 % tetracycline. • Fungi Aspergillus caespitosus harvested 92.69 % of microalgal biomass. • The mechanism for treating tetracycline by microalgae-fungi consortia was studied. • Extracellular polymeric substances boost tetracycline removal and biomass harvest. • Amino acid and nucleotide metabolism were activated to cope with tetracycline. This study focused on tetracycline (TC) as the target antibiotic and utilized the emerging microbial system microalgae-fungi consortia to treat it. Results indicate that consortia composed of microalgae Chlorella sp. HL and fungi HW12 ( Aspergillus caespitosus ) (HL-HW12) exhibited the optimum TC removal (93.00 %, residual concentration: 2.73 mg/L) and biomass harvesting efficiency (92.69 %) among the five kinds of constructed microalgae-fungi consortia. Mechanism analysis indicated that outside the cell, microalgae-fungi consortia strengthened TC removal and biomass harvesting by augmenting the contents of proteins, polysaccharides, fulvic acids, and humic acids. While within the cell, microalgae-fungi consortia adjusted the abundance of critical metabolites in the amino acid metabolism, nucleotide metabolism, and other metabolic pathways to cope with the coercion of TC and facilitated its elimination. This study not only provides good TC microbial treatment systems but also comprehensively reveals the TC removal and metabolic response mechanisms by microalgae-fungi consortia.