Microbial Colorants And Their Application In Dyeing Of Protein Fibers

In this paper,the nature of colorants secreting from three microbial bacteria,Metarhizium anisopliae,Phellinus linteus and Streptomyces violaceus,were studied and the colorants were applied in protein fabrics.The experiments were designed according to the different characteristics of microorganism.This research enriched the application of microbial pigments in dyeing.The first research object was Metarhizium anisopliae.The rDNA D1/D2 and ITS gene sequences of this strain were identified firstly.The properties of the colorant and the effects of culture medium components and dyeing conditions were investigated.The results showed that the strain shared more than 99%homology with the Metarhizium anisopliae.In the UV-Vis absorption spectra of this yellow colorant,the maximum absorption wavelength was observed at 366nm.Glucose was the most appropriate carbon source in fermentation and more colorant could be obtained under the following conditions:30g/L glucose,inoculum4%?v/v?,fermented in the incubator with 160r/min at 30?for 4 days.Moreover,the pH,temperature and metal ions had a big influence on the stability of the yellow colorant from Metarhizium anisopliae.The optimal dyeing process was pH=4,at 80??silk fabric?/90??wool fabric?for 60min.The rubbing fastness of Metarhizium anisopliae dyed fabrics were rated at Level 4 or 4-5,staining fastness Level 4-5,while the light fastness was only Level1-2 and needed to be further improved.The second research object was Phellinus linteus.The ultrafine powder of fruiting body was purified to dye silk fabric and the purification technology,the stability,thermodynamics/kinetics model,dyeing process were investigated in this research.The results showed that the maximum absorption wavelength of purified Phellinus linteus yellow colorant was observed at 447nm.The purified colorant with high yield could be obtained using 70%CH₃OH as the solvent and purified at 60?for 60min,3 times.Furthermore,the acid-base?pH?7?and thermal??100??stability of this colorant was good.However,Fe²⁺and Fe³⁺had a greater impact on the stability.The linear fitting equation at 80?was y=0.052x+0.359,R²=0.99317,k=0.0078g?mg·min?^-1,t_1/2=6.8014min;while at 90?was y=0.050x+0.202,R²=0.99706,k=0.0127g?mg·min?^-1,t_1/2=3.9879min.The absorbing type of the Phellinus linteus yellow colorant and silk fibers was Nernst.In addition,the optima dyeing process was 1.5g/L Al³⁺as a mordant,dyed at pH=4,90°C for 2 h.The soaping and rubbing fastness of Phellinus linteus dyed fabrics were rated at Level 3-4 or 4-5,respectively.However,the light fastness was only Level 2.The third research object was Streptomyces violaceus.The Streptomyces violaceus purple colorant could be divided into two kinds:Intracellular and extracellular colorant.The results showed that the content of extracellular colorant was higher.Three absorption wavelength could be observed at 585-610nm,540-560nm,495-510nm in the UV-Vis absorption spectra.This Streptomyces violaceus colorant presented different colors under acid/alkaline.The thermal??100??stability of this colorant was good.The optimal dyeing process was pH=10,at 90?for 40min.The Streptomyces violaceus dyed fabric showed higher color fastness than the two former.