Living Colours: Development of Microbial Culture Collection for Use as Microbial Colour Pigments in Textile Dyes

Abstract

The textile industry is one of the largest worldwide polluters of clean water due to the heavy use of synthetic dyes. Synthetic dyes are harmful to aquatic life and to human health. To overcome this, natural dyes are being explored as a healthier and more eco-friendly alternative. Several advantages such as ease of extraction, availability, high yields and no seasonal variation make microbial pigments the most ideal source of natural pigments. This study was done to isolate colour pigment producing bacteria and fungi from soil collected from organic farms from various locations in Sri Lanka. In total, 9 pigment producing bacteria and 3 pigment producing fungi were isolated. Gause’s synthetic agar yielded the most pigmented isolates. Extracellular pigments produced by 5 of the bacterial isolates were extracted by a water based method. The antibacterial activity of the pigments in their crude and concentrated forms was tested using the well diffusion method against E.coli ATCC 8739 and Staphylococcus aureus ATCC 6538P. Inhibition zone against S.aureus was observed for both crude (12.33±0.58mm) and concentrated pigments (9.67±0.58mm) extracted from purple pigment producing bacterial isolate (BPU). This pigment has the potential to be used in antibacterial textile preparation. Extracted pigments were used to dye scoured cotton fabric with the use of 3% alum as mordant. Pigment from BPU isolate resulted in better coloured fabric.