Studies On Screening Of Higher Gamma-Aminobutyric Acid-Producing Monascus And Optimization Of Fermentative Parameters

gamma-Aminobutyric acid (GABA), a hypotensive agent, can be produced by Monascus spp. Two hundred and fifteen GABA-producing Monascus strains were isolated from fermented bean curd and red-mold rice. The strain M6 with the highest production level of GABA (3.657 g/L) was isolated from fermented bean curd by using PDB with 0.5% monosodium glutamate (MSG) and identified as Monascus ruber based on morphological and ITS region sequence comparisons. The strain M6 was irradiated by UV to raise GABA production. The mutant strain of M6-13 had the highest GABA yield of 5.527 g/L, which was 1.5 times higher than that of the original strain M6. In addition, the strain M6-13 still had stable yield of GABA and no reverse mutation after sub-cultured for 15 generations. GABA production level of the mutant strain M6-13 increased to 7.826 g/L in submerged flasks culture by use of the orthogonal experiment method. Based on this, process analysis and optimization of GABA production of the strain M6-13 were studied in 3.7-L vessel fermentor and the maximum GABA yield reached 13.470 g/L.