Enhancement of Monacolin K Production by Intergeneric Hybridization between Monascus purpureus (Arg-) and Monascus ruber (Thi-, Met-) Auxotrophs

Abstract

This study aims to reconcile industrially suitable strains of higher red pigment producing Monascus purpureus MPA5 and higher Monacolin K producing Monascus ruber MRA7, were tried to fuse for development of increased efficacy of targeted secondary metabolites production. The optimum concentration of protoplast mixture was standardized, before the fusion experiment. The effective fusion was observed with the solution of 30 % PEG 6000, CaCl2.2H2O (0.01 M) and glycine (0.05 M). Colonies of the fusants were segregated using complete medium. The fusants were irradiated under UV- light in LD50 dose. On the basis of non-segregation of colony appearance after repeated subculturing in complete medium, 8 colonies were selected. Finally, one of the stable fusant MF11 grew more rapidly than one of the parental strain M. purpureus MPA5, but not as fast as M. ruber MRA7, were selected and grown on low grade rice as solid substrate for production of metabolites. Production of red pigments, alpha-amylase and acid protease were at intermediate stage between two parental strains but enhancement of Monacolin K was observed. High performance liquid chromatography (HPLC) analysis was revealed that Monacolin K content was increased as much as two and half times than the parents. No fluorescent yellow band was detected in TLC plate, indicating of citrinin negativity of the fusant MF11. It is the first report of enhanced Monacolin K production by a stable fusant of Monascus sp.