<P><B>Abstract</B></P> <P>We report a recycling bioresource involving harvesting of <I>Microcystis aeruginosa</I> using the bioflocculant (MBF-32) produced by <I>Enterobacter aerogenes</I> followed by the recovery of the harvested <I>M. aeruginosa</I> as the main substrate for the sustainable production of MBF-32 and biohydrogen. The experimental results indicate that the efficiency of bioflocculation exceeded 90% under optimal conditions. The harvested <I>M. aeruginosa</I> was further recycled as the main substrate for the supply of necessary elements. The highest yield (3.6±0.1g/L) of MBF-32 could be obtained from 20g/L of wet biomass of <I>M. aeruginosa</I> with an additional 20g/L of glucose as the extra carbon source. The highest yield of biohydrogen was 35mL of H<SUB>2</SUB>/g (dw) algal biomass, obtained from 20g/L of wet biomass of <I>M. aeruginosa</I> with an additional 10g/L of glycerol. Transcriptome analyses indicated that MBF-32 was mainly composed of polysaccharide and tyrosine/tryptophan proteins. Furthermore, NADH synthase and polysaccharide export-related genes were found to be up-regulated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bioflocculant from <I>E. aerogenes</I> is involved in the bioflocculation of <I>M. aeruginosa</I>. </LI> <LI> <I>M. aeruginosa</I> is the substrate for bioflocculant and biohydrogen production. </LI> <LI> Bioflocculant yield from 20g/L of wet biomass of <I>M. aeruginosa</I> was 3.6±0.1g/L. </LI> <LI> The highest yield of biohydrogen was 35mL of H<SUB>2</SUB>/g (dw) algal biomass. </LI> <LI> The metabolic pathways of bioflocculant and biohydrogen production were determined. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>