Insight into the metabolic changes during germination of Aspergillus niger conidia using nLC-qTOF

Aspergillus niger is a ubiquitous organism that impacts clinical settings and the biotechnology industries. To gain insight into the germination of conidia in A. niger , a gel-free protein profile could be a platform to illustrate critical proteins and their involvement in biochemical pathways during germination. A clinical isolate of A. niger (NCCPF 790032) cultured on Sabouraud dextrose showed more than 90% conidia germination at the 7 h time point. To profile proteins, protein extraction and estimation were followed by nLC-qTOF mass spectrometer analysis. Using the UniProt database, Protein Lynx Global Service (PLGS 3.0.2) software analyses showed 883 proteins across Aspergillus spp., including 108 proteins to A. niger . Orthologues of A. niger ’s protein were observed in A. nidulans , A. fumigatus , A. clavatus , A. oryzae, A. fischeri , A. terreus , A. flavus , A. parasiticus , A. kawachii , A. aculaetus , A. awamori , A. ficuum , A. tubingensis , A. versicolor , Augochlora phoenicis , and Anexaireta variicolor . Proteins categorized based on Gene Ontology (GO) (biological process, molecular function, and cellular component) clustered primarily to GO terms belonging to cell wall biogenesis, energy, carbohydrate, amino acid, protein metabolism synthesis, among the others. The expression of serine-threonine protein kinases during the germinating conidia of A. niger involved in MAPK-mediated signaling was observed. Expression of tyrosinase in A. niger favored conidial pigmentation via the DOPA-melanin biosynthesis pathway. Overall, the identity of proteins showed that these proteins belong to organelle biogenesis (ribosome, mitochondria) and metabolism of macromolecules (protein, carbohydrate, and nucleic acids) during the germination of A. niger conidia. The data could be helpful in comparative proteomics relevant to pathogenic fungi or to understand the biology of Aspergillus spp. Graphical abstract