Background Melanins are structurally complex biomolecules found across all kingdoms of life. Elucidating the biochemistry of melanin is difficult due to its heterogeneity and chemical complexity. We have previously characterized peptidomelanin: a water-soluble melanin secreted by germinating spores of Aspergillus niger strain: melanoliber (MTCC 13366). Methods While we have characterized the polymer’s biochemical composition and biosynthetic pathway, the mechanisms that trigger secretion of the polymer remain poorly understood. In this brief communication, we describe the environmental cues that trigger peptidomelanin secretion. Results We find that peptides in the extracellular media trigger significantly more peptidomelanin secretion, compared to sugars, amino acids, and proteins. Using fluorescence microscopy, we observed selective extracellular peptide binding to the outer surface of A. niger melanoliber spores. Conclusions We infer that Aspergillus niger melanoliber spores sense extracellular peptides via surface-associated interactions, and that this recognition step is required to trigger peptidomelanin secretion.
Lhamu et al. (Thu,) studied this question.