Monascus purpureus mutant and its use in preparing yellow pigment

#The invention provides a mutant of Monascus purpureus; and its use in preparing yellow pigments.

#Historically, the genus Monascus has been wildly used as food additives in China and other Asiatic contries. U.S. Pat. Nos. 4,442,209, and 5,457,039 have disclosed the utilization of Monascus sps. in the production of red, yellow and orange pigments which are served as the major sources of natural pigments. According to U.S. Pat. No. 5,429,943, the ratios between the red and yellow pigments among the Monascus pigments are mostly 1:1, and the hue of the Monoscus pigments shows red. Therefore, the Monascus pigments are useful in the production of red pigments. The relevant prior art references disclosing the utilization of genus Mocascus in the production of Monascus yellow pigments include: U.S. Pat. No. 5,013,564, wherein a reduction reaction is used to treat Monoscus pigments; and JP 55088696 and 81053589, wherein the cultural conditions, such as pH value or cultural medium, are controlled to achieve the purpose of producing Monascus yellow pigments.

#Blanc et. al. (International Journal of Food Microbiology; 27, (1995), 201-213) found that Monascus sps. were capable of producing a fungal toxin (citrinin), which received considerable attention to the safety of the Monascus pigments. JP 7274978 discloses a method to reduce the amount of citrinin (lower than 1 ppm) by a mutant strain. However the pigments produced by the method are mostly red pigments and the yellow pigments can only be obtained by an additional processing treatment. Although Monascus sps have been widely used in the production of red pigments, a Monascus strain which could produce a higher proportion of yellow pigments and a lower amount of citrinin had not been found until now.

#(1) Analysis of Yellow and Red Pigments

#Fermentation liquid of the strain was diluted properly, and the OD400 and OD500 values of the diluted liquid were determined at 400 and 500 nm by the spectrophotometer for the yellow and red pigments, respectively. The ratios of the readings of OD400 to OD500 were used to determine the quality of the yellow pigments, i.e. a higher value of the ratio represents a higher proportion of the yellow pigments.

#(2) Quantitative analysis of Citrinin