Effect of amino acids on pigments, citrinin, and lovastatin production by Monascus purpureus under static conditions

Abstract

Monascus spp. is known to produce many secondary metabolites including pigments, statin, and undesired mycotoxin. M. purpureus MTCC 410 strain was grown statically for ten days in potato dextrose broth supplemented with 1% UV sterilized amino acids. Whatmann filter No. 1 was used to separate the developed mycelia from the broth to get the intracellular pigment as the extracellular one is left in the filtrate. The pigment concentration was estimated by the calorimetric method for different wavelengths and expressed in colour value units (CVU). The presence of citrinin in the growth medium was checked under UV light at 350 nm and quantification was done with highperformance liquid chromatography column along with loop injector of 20 μl, and Shimadzu CLASS-VP version 5.032 software. The maximum biomass (143.6 g/l) was observed with supplementation of 1% D-serine to the medium, whereas the maximum intracellular pigment yield was observed with supplementation of L-histidine monohydrochoride (yellow – 4.48, orange – 3.97 and red pigment – 2.0 CVU/ml). The maximum extracellular pigment yield was observed with supplementation of glycine (yellow – 2.18, orange – 1.65 and red pigment – 1.38 CVU/ml to the growth medium). The maximum lovastatin yield was observed with supplementation of L-cysteine mono hydrochloride and concentration of 2064 mg/l. Maximum citrinin (1.29 mg/l) was observed with supplementation of DL-norleucine to the growht medium. M. purpureus requires suitable concentration of organic nitrogen in the form of amino acids for a higher yield of secondary metabolites such as supplementation of 1% L-cysteine monohydrochloride or L-tyrosine in the growth medium under submerged cultivation. None of the tested amino acids produced citrinin under experimental conditions making the outcome beneficial for industrial purposes.