Bioconversion of agricultural wastes into chitin: fungal-based production strategy for cheese whey treatment

Justification
Chitin, a biocompatible, biodegradable, and non-toxic biopolymer, has significant applications in emerging technologies. Traditional methods of isolating chitin from crustaceans are time-intensive, costly, and pose risks. Fungal-derived chitin offers a promising alternative. Additionally, leveraging industrial by-products like cheese whey for fungal cultivation presents an eco-friendly and cost-effective approach to chitin production while addressing waste management challenges in the dairy industry.

Objective
This study aims to investigate the feasibility of using cheese whey as a low-cost, sustainable alternative growth medium for fungal chitin production and to evaluate its bioremediation potential by reducing chemical oxygen demand (COD).

Methods
Cheese whey, donated by the SDSU Dairy Plant, was used as the primary growth medium for fungal strains Aspergillus niger and Trichoderma reesei. The whey was compared to a standard growth medium, glucose yeast extract (GYE). Fungal fermentation was initiated at time zero, with samples collected every 72 hours up to 216 hours. The fungal biomass was harvested, dried, and analyzed for crude chitin percentage, molecular weight, protein content, and bioactivity. The supernatant was evaluated for residual proteins, lactose content, and COD to assess the bioremediation potential of cheese whey.

Results
Both fungal strains demonstrated effective growth on cheese whey as an alternative medium. The dried fungal biomass showed significant chitin production, with crude chitin yield, molecular weight, and protein content comparable to those grown on the standard GYE medium. Bioactivity testing confirmed the functional quality of the extracted chitin. The supernatant analysis revealed a substantial reduction in residual proteins, lactose, and COD, highlighting the potential of cheese whey for bioremediation. These findings support the viability of using cheese whey for fungal chitin production, offering a sustainable and cost-effective approach to valorizing industrial by-products.