Isolation and Characterisation of Pigments from Pigment-producing Microorganisms Isolated from Environment and Their Antibacterial Activity

Abstract

Abstract In the food industry, there is always a demand for food products which are colourful, have an attractive appearance, and also have nutritional and health-enhancing properties to attract the attention of consumers. Synthetic pigments are widely used in the global market, however, they can cause many side effects such as hyperallergenicity, carcinogenicity and other toxicological problems. Recent studies have revealed that microorganisms are an abundant source of natural colours that allow the industrial production of safe, environmentally friendly biodegradable pigments. The aim of the work was to isolate pigmented microorganisms from environmental samples, select fermentation conditions, isolate pigments from microorganisms and check their antimicrobial activity. Pigments have been isolated from various sources such as soil, food waste, flour, etc. Growth parameters of pigment-producing microorganisms such as growth temperature, pH, tryptone and NaCl concentration in the medium were optimised to evaluate pigment production. After fermentation, five types of pigments were isolated by cell lysis with an ultrasonic bath and solvent extraction. The antimicrobial activity of the extracted pigments was investigated. During the study, the optimal conditions for the growth of microorganisms were determined: temperature of 30 °C, pH of 7, concentration of 3% tryptone and 6% NaCl in the culture medium. Glycerol was found as an additional carbon source, which had a positive effect on pigments production. The results of the antibacterial effect of the extracted pigments showed that P. aeruginosa was the most sensitive to the effect of the pigments. The pink-red pigment showed the highest antimicrobial activity against the tested pathogenic bacteria.