Extracellular Yellow Pigments Produced by Chaetomium globosum H-1 Isolated from Spalted Wood: Fermentation Regulation, Multidimensional Characterization, and Sustainable Wool Dyeing

Abstract

Microbial extracellular pigments are renewable colorants for sustainable textile dyeing. A yellow-pigment-producing fungal strain, H-1, isolated from spalted wood, was identified as Chaetomium globosum and evaluated for pigment production, characterization, stability, bioactivity, and wool dyeing. Stepwise single-factor screening indicated suitable culture conditions of initial pH 7, 25 °C, 10 d, 25 g/L glucose, 7 g/L fish peptone, and 0.25 g/L K2HPO4. Fourier-transform infrared spectroscopy (FTIR) revealed hydroxyl, aromatic, and C-O-C groups, and ultra-high-performance liquid chromatography-high-resolution tandem mass spectrometry (UHPLC-HRMS/MS) putatively annotated representative components including Chaetomugilin D and Armochaetoglobin G. The crude pigment produced preliminary inhibition zones of 14.30 ± 0.04 and 10.01 ± 0.17 mm against Staphylococcus aureus and Escherichia coli, respectively, while crude fermentation filtrates showed measurable hydroxyl and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging capacities under fixed assay conditions. The pigment was more stable under neutral to alkaline pH and short-term heating at 40–100 °C. Wool showed higher dye affinity than cotton, linen, and silk. Response surface methodology (RSM) optimized wool dyeing at pH 2.35, 91 °C, 80 min, and 2.04 g/L potassium aluminum sulfate, yielding a color strength (K/S) value of 11.65. After three dye-bath reuse cycles, K/S decreased by 16.28%, and washing/rubbing fastness remained above grade 3 under GB/T tests. These results support further development of Chaetomium globosum H-1 extracellular pigments for natural wool coloration and dye-bath reuse.