Production Of Monacolin K And GABA By Liquid Fermentation Of Monascus Spp.

Monascus purpureus WX and Monascus pilosus GM100 were choosed to produce Monacolin K and GABA by liquid fermentation respectively.Response Surface Methodology was applied to optimize the culture conditions for Monacolin K produced by Monascus purpureus WX. The maximal Monacolin K yield 297.4mg/L was obtained under the following conditions: glycerin 102.2 g/L, soybean powder 29.2 g/L , NaNO₃ 2.0g/L, 1.0g/L, 1.0g/L, initial pH 4.5, cultured for 15d at 26℃. The optimized culture conditions resulted in a 3.9 times increase of Monacolin K yield, as compared with the original conditions.The optimal culture condition of Monascus pilosus GM100 for GABA production is: rice powder 5%, glucose 7%, soybean powder 1.0 %, yeast power 1.5%, MSG 0.8%, NaNO₃ 0.5%, KH₂PO₄ 0.15%, MgSO₄·7H₂O 0.1%. The content of GABA is 395mg/L after cultured for 12 days under 30℃, 180 rpm.Glutamate decarboxylase of Monascus pilosus GM100 was purified from the cell-extract by ammonium sulfate fractionnation and Sepharose CL-6B column chromatography. They overall yield of the purified enzyme was 4.74% with 6.56 purification folds. The optimum temperature of Monascus GAD was 30℃and the enzyme showed an high activity at acidic pH (4.4-4.8) range. The activity of Monascus GAD increased as culture time and reached its peak on the 6^th day.