Breeding And Fermentation Study Of Strains With Monascus Pigment And Glucoamylase Production

Monascus strains with Monascus pigment and glucoamylase production was isolated and purified from red yeast rice provided by FuJian Gutian Monascus Industry Association.Through mutation breeding, mutatant strain with high Monascus pigment and high glucoamylase was obtained respectively. Fermentation conditions both liqiud-state and solid-state, stability of Monascus pigments, enzyme properties of glucoamylase, etc was studied, the results are as follows:1、By means of dilution plate count, Monascus strain named C26 and A1 was isolated and purified from red yeast rice, with high producing red pigment and glucoamylase. They were identified as Monascus purpureus based on morphological and ITS sequence. A mutant strain 183-3 with high stable capacity of Monascus pigment production and a mutant strain G6 with high stable glucoamylase production were screened through spore suspension ultraviolet-lithium chloride mutation.2、Research results on the stability of Monascus pigment showed:pigment extract being sensitive to light, when reserved for 10 days, the retention rate of pigment was 76.20% in dark,63.42% irradiated by indoor natural light and only 3.98% irradiated by sunlight; The thermostability of high concentration pigment extract was no better than low concentration pigment extact, after 5h treatment under 80℃, the retention rate was 27.80%; The Monascus pigment has good stability with pH 2-10. Results on glucoamylase enzyme properties showed:the optimum reaction temperature is 55℃, the optimal reaction pH is 4.5, glucoamylase is relatively stable at 40℃ below and acidic pH (especially pH 4-5).3、Results on fermentation study both solid-state and liqiud-state of mutant strain 183-3 producing Monascus pigment showed, the liqiud fermentation conditions were: soluble starch 12%, peptone 1%, MgSO40.05%, MnSO40.015%, ZnSO40.01%, initial pH 5.0, seed age 48h, inoculation amount 8%(v/v), medium volume 50mL/250mL, rotation speed 180r/min and temperature 32℃, the red color value of Monascus pigment reached to 350.8U/mL when fermentated in these conditions after 12d; The fermentation conditions in solid device (25cm ×17.5cm × 8cm) were rice 400g, peptone 1%, ZnSO40.01%,10%(v/w) inoculation, initial moisture content 40%, and the red color value reached to 7210U/g (pigment hue was 0.85) when strain 183-3 was incubated at temperature 32℃, relative humidity 80% for 13d.4、Results on fermentation study both solid-state and liqiud-state of mutant strain G6 producing glucoamylase showed, the liqiud fermentation conditions were:rice flour 8%, peptone 1%, ZnSO40.01%, FeSO40.005%, MnSO40.015%, KC10.1%, initial pH 4.0, seed age 48h, inoculation amount 12%(v/v), medium volume 50mL/250mL, rotation speed 150r/min and temperature 32℃, the glucoamylase activity reached to 1652.36U/mL when fermentated in these conditions after 10d; The fermentation conditions in solid devie were:rice 400g, peptone 2%,12%(v/w) inoculation, initial moisture content 40%, and the glucoamylase activity reached to 5399U/g when strain G6 was incubated at temperature 32℃, relative humidity 80% for 12d.