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Influence of Diet and Growth Conditions on the Carbon and Nitrogen Stable Isotopic Composition of Aspergillus niger Mycelium: Insights for Fungal Chitosan Characterization

Summary

Scientists studied how the diet of Aspergillus niger fungus affects the chemical fingerprint of chitosan it produces. By analyzing carbon and nitrogen isotopes in fungal biomass grown on different diets, they found that the fungus’s food source leaves distinctive isotopic signatures. This discovery could help verify whether chitosan in food and wine products truly comes from fungi rather than being fraudulently substituted with cheaper animal-derived alternatives.

Background

Chitosan, a biopolymer derived from chitin, is used in various industrial applications including winemaking. While fungal-derived chitosan is preferred over animal-derived sources due to allergenicity concerns, authentication methods are limited and labor-intensive. Stable isotope ratio analysis has emerged as a promising approach for distinguishing fungal from animal-derived chitosan.

Objective

This study investigates the relationship between carbon and nitrogen stable isotopic composition of Aspergillus niger mycelium and its growth diet under controlled cultivation conditions. The aim is to establish the correlation between nutrient sources and isotopic signatures to support the authentication and traceability of fungal-derived chitosan.

Results

Carbon sources significantly influenced δ13C values, with C4-glucose diets showing more negative Δ13C values than C3-glucose. Nitrogen sources affected isotopic fractionation differently: potassium nitrate yielded negative Δ15N while ammonium chloride produced positive Δ15N. Continuous aeration significantly decreased δ15N values, suggesting partial assimilation of atmospheric nitrogen.

Conclusion

This work provides the first experimental evidence linking fungal diet composition to stable isotopic signatures in A. niger mycelium. While δ13C reliably reflects carbon source origin, δ15N shows complex fractionation dependent on nitrogen source type and physiological fungal responses. These findings establish a scientific foundation for applying stable isotope analysis to authenticate fungal-derived chitosan.
  • Published in:Molecules,
  • Study Type:Experimental Study,
  • Source: PMID: 41157159, DOI: 10.3390/molecules30204142
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