Improvement of red pigment citrinin production ratio as a function of environmental conditions by Monascus ruber

The growth and metabolic behaviour of the filamentous fungus Monascus ruber were studied in submerged cultures under various aeration and agitation co nditions. Improving the oxygen supply, by increasing either the air input o r the agitation speed, resulted in modified metabolism: the biomass yield, the consumption of the nitrogen source (monosodium glutamate), and the prod uction of secondary metabolites (red pigment and citrinin) all increased. H owever, the citrinin production increased more than that of the red pigment . In consequence, a low oxygen transfer coefficient was required to improve the red pigment/citrinin production ratio. (C) 1999 John Wiley & Sons, Inc .