Optimization of biomass production by Monascus purpureus in culture medium containing dairy sludge

Cheap compounds and wastes of various industries have a set of nutritious compounds that can be used as a culture medium for different strains to produce metabolites with high nutritional value and expensive. Pigment production from microbial source is of interest because it is safe for human health. In this study, with the aim of producing red pigment from the mold Monascus purpureus, firstly, the effect of culture medium factors, potato dextrose broth, yeast extract-sucrose, dairy sludge, soybean meal, sugar cane molasses, whey, temperature, glucose, monosodium glutamate and ammonium sulfate on production biomass (a measure of pigment production) was evaluated through Plackett-Burman design. Then the factors were optimized based on the central square design. Based on the obtained results, dairy sludge base culture medium, glucose, monosodium glutamate and temperature had a positive effect on growth and biomass production (pigment production). With optimization, biomass production in 10% dairy sludge, 0.999% monosodium glutamate, 27°C temperature and 9.83% glucose were obtained with the production of 26.15 g/l of biomass as the optimal state. The results show the capability of dairy sludge waste in the growth of microbial strains and production of significant products.