Dyeing properties of microbial prodiginine from Zooshikella rubidus for silk fabrics

The dyeing properties of prodiginine from Zooshikella rubidus for silk fabrics have been studied. Prodiginine was extracted from microbial cells with 100 % ethanol. Optimal silk dyeing was carried out using an infrared dyeing machine at 60 °C for 60 min, at 1.0 % (owf), using a 1:50 bath ratio at pH 4.0. Optimal concentrations of Al and Ti mordants in silk dyed with microbial red colorant were 2.0 and 1.0 % (owf), respectively, as determined by dye uptake (K/S). Color fastness to washing, water, rubbing, perspiration, and dry cleaning was measured as grades 3-5. However, light fastness was grade 1, similar to that for other natural dyes. When Al and Ti mordants were used on silk, fastness to washing and perspiration was improved by more than 1 grade.