Assessment of the Safety of Chlorella fusca Grown in Refined Swine Manure Liquid Fertilizer for Bioresource Applications.

Objective: Chlorella fusca, a microalga with promising applications in sustainable biotechnology, is of growing interest for its nutritional value, environmental benefits, and bioactive properties. This study investigated the safety and viability of cultivating C. fusca in refined liquid fertilizer derived from pig manure.

Methods: Refined liquid fertilizer derived from swine manure was used as a nutrient medium for cultivating C. fusca. To compare its biochemical properties with those of commercial Chlorella products, the cultivated algae were subjected to proximate composition analyses to determine their water, crude-protein, crude-fat, and ash-free-extract contents. Cytotoxicity was assessed via MTT and WST-1 assays, and an acute toxicity study was performed in Sprague-Dawley rats to evaluate physiological effects according to body weight changes and serum biomarkers. Histopathological examination of the liver, kidneys, and lungs was conducted to detect any toxicological effects. Additionally, antibiotic residues, microbial safety, pesticide contamination, and heavy-metal content were evaluated to confirm overall product safety.

Results: Proximate analysis revealed significant differences in moisture and crude-fat content compared to commercial Chlorella products. Cytotoxicity assays demonstrated enhanced immune cell activity at higher concentrations (P < 0.05). No significant body weight changes were detected in rats, and serum analysis indicated a dose-dependent reduction in alkaline phosphatase levels in 1000- and 2000-mg/mL treatment groups (P < 0.05 and P < 0.01, respectively). Histopathological examination confirmed the absence of significant alterations in the liver, kidneys, and lungs, supporting its safety as a dietary supplement. Antibiotic residue, microbial safety, pesticide contamination, and heavy-metal analyses showed levels that were undetectable or below safety limits, confirming the safety of C. fusca.

Conclusions: Chlorella fusca cultivated with refined liquid fertilizer derived from swine manure was found to be safe for use in various biotechnology applications. Our findings imply its potential as a bioresource, including as a feed additive.