Microalgae are widely used as live feed in aquaculture due to their high nutritional value and digestibility. However, conventional photoautotrophic cultivation faces significant limitations including light availability constraints, high CO₂ supply costs, and seasonal variability. While mixotrophic strategies offer alternatives, most studies rely on expensive purified organic carbon sources that limit industrial scalability.
The research team at Jiangsu University conducted systematic screening of various organic carbon and nitrogen sources, revealing unexpected species-specific responses. Unlike some other diatom species, C. muelleri was inhibited by glucose and ethanol but significantly stimulated by organic acids—particularly acetic acid, which achieved 2.1-fold higher cell density at optimal concentrations. Organic nitrogen sources including glutathione and small peptides also enhanced growth compared to inorganic nitrate, with glutathione showing the strongest promoting effect at 1.36-fold higher than sodium nitrate controls.
To create an optimized fermentation product, the team constructed a function-oriented microbial consortium. Screening various bacterial strains identified Lactobacillus plantarum, Bifidobacterium lactis, Lactobacillus buchneri, Candida utilis, and Bacillus subtilis as high acetic acid producers. Through co-fermentation optimization, a 3:2:1 ratio of lactic acid bacteria : yeast : Bacillus yielded the highest acetic acid concentration of 21 mg/g in the fermented hydrolysate.
Response surface methodology based on Box–Behnken design was applied to maximize small peptide production, achieving an experimentally validated peptide content of 36.96%. This integrated framework for converting agricultural waste into microalgae cultivation nutrients contributes to sustainable aquaculture and circular bioeconomy principles—addressing both waste management challenges and affordable feed production needs.
The work entitled “Enhanced Chaetoceros muelleri growth using optimized fermented agricultural waste” was published on Systems Microbiology and Biomanufacturing (published on Mar. 23, 2026).
DOI: 10.1007/s43393-026-00457-5