Growth and pigment production of Monascus purpureus EG and its beneficial effects

Abstract

Pigments play an important role in the pharmaceutical industry as well as in the food industry. Biological synthesis of pigments has attained more revenue for easy extraction, high growth rate and high yield. The production of pigments by Monascus purpureus EG was investigated in several static batch cultures, the most suitable medium for its yellow, orange, and red extracellular pigment production was yeast glucose medium (YG), while malt extract medium (ME) had maximum production for its intracellular pigment. The effect of some physical factors on growth and pigment production was studied. Direct illumination inhibited growth and pigment production. Antimicrobial activities of pigments were observed against selected Gram-negative (G-ve) and Gram-positive (G+ve) bacteria. The antibacterial effects of red pigment on G- and G+ were highly effective compared to yellow and orange pigments. The extracted pigment was used for the reduction of the aqueous silver nitrate into silver nanoparticles (AgNPs). The biosynthesized AgNPs were structurally characterized using UV-VIS Spectra which showed absorption peaks at 437, 453 and 447 nm for pH values 3.5, 6.5 and 9.5, respectively. The optimum pH for the maximum synthesis of nanoparticles was 6.5. It showed no nitrate reductase activity, but the synthesized AgNPs exhibited strong antimicrobial activity against G+ and G- bacteria.