Potentials of a new mutant of Monascus mould on production of natural yellow pigments
1993
Somchai Krairak
Improvement of Monascus sp. KB 11304, an excellent cassava starch utilizing red fungus, had been carried out. By exposing the wild type to UV irradiations for 10 minutes gave a mutant, Monascus sp. KB 10M16, which produced higher yields of red pigment. And extended UV exposure time of 20 minutes to this red mutant therefore gave a new yellow mutant, Monascus sp. KB 20M10.2 which produced yellow pigment (lambda max 370 nm) instead of red pigments (lambda max 420 and 500 nm) in neutral pH medium. Whreras native Monascus strain was found to give yellow pigment only in acidic medium. The optimal medium for yellow pigment production of Monascus sp. KB 20M10.2 was composed of 3 % cassava starch, 5 % soybean flour and 13.3 milligrams per litre of Tween 80. Liquid inoculum was suitable for Monascus sp. KB 20M10.2 to produce yellow pigment and could reduce the inoculum preparation time and amount from 4 weeks and 3 % (w/v) of yellow rice koji inoculum to 3 days and 3 % (v/v) as well. The physical appearance of the pellet seemed to be directly to the production of yellow pigment of Monascus sp. KB 20M10.2. The needle form pellet gave higher pigment production than spherical or thread-like pellet. Fed-batch cultivation was also found to improve the yellow pigment production. Two-third of the optimal medium was cultivated for 2 days and then one-third of the medium was further added to fermented masses. The result showed that the yellow pigment production of this fungus was increased in the fed-batch cutivation, yielding 959 U/ml within 9 days of fermentation. Having a propeller and draft tube assembled in the 5-litres fermentor gave the axial flow rheology, causing a reduction in its wall growth while improving the pigment production as well.
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