Natural dyes are gaining importance for their non-toxic and bio-degradable nature. The development of cost effective production of dyes from bacteria, actinomycetes, micro- & macro-fungi & its application in textiles and medical textiles was successfully developed. Besides the dyes, pigments from microbial sources such as carotenoids, flavonoids, betalains, quinines and some tetrapyrroles are also being tested as promising and cost-effective alternatives to synthetic dyes. As microbes can be easily grown in a short time and the dyes extracted from them are natural & eco-friendly, they can be produced in a decentralized manner as an alternative to synthetic products.
The process of cultivation microfungi viz., Curvularia sp., Pestalotiopsis sp., Phoma sp. etc. and macro-fungi (the mushroom forms) viz., Ganoderma lucidum and Pycnoporus sanguineus using cost effective, locally available substrates have already been developed. The dyes extracted from both micro and macro-fungi when applied on cotton fabric and yarns employing various mordants produced vivid colours in textiles & yarns with fair to good wash fastness properties.
Microbes, especially bacteria produce variety of coloured metabolites or micro-chrome that can be explored to substitute the existing synthetic colourants as they can grow in a short span of time with minimal nutrient supplements. A technology comprising the following processes: cultivation of bacteria such as Pseudomonas sp., Serratia sp. and Chromobacterium sp. on low cost suitable medium for production of pigments / dyes, the process of dye extraction and dyeing of cotton, linen & woollen yarns using these these microbial dyes / pigments was developed to deploy it for the artisans, who are engaged in traditional dyeing using natural dyes. In addition, these microbial dyes are also used for colouring of wax & handmade papers. Dyeing of yarns using natural dyes and various mordants created various vibrant colour shades that have paved a new path to replace synthetic dyes completely in the near future.
Actinomycetes are Gram-positive bacteria with fungal morphology and are rich source of secondary metabolites with diverse biological activity. The growth an actinomycetes, Streptomyces sp., the production of yellow dye by this species and the application of the dye on to cotton fabrics have also been tried. As the results from the initial studies are encouraging, optimization of media and scaling up of dye production are under progress.
