Abstract
Monascus species have been used for the production of many industrially and medically important metabolites, most of which are polyketides produced by the action of polyketide synthases that use acetyl-CoA and malonyl-CoA as precursors, and some of them are derived from acetate. In this study the effects of acetic acid, and two kinds of acetates, sodium acetate and ammonium acetate at different concentrations (0.1%, 0.25% and 0.5%) on the morphologies, biomasses, and six major Monascus pigments (MPs) of M. ruber M7 were investigated when M7 strain was cultured on potato dextrose agar (PDA) at 28 °C for 4, 8, 12 days. The results showed that all of the added acetate species significantly affected eight above-mentioned parameters. In regard to morphologies, generally the colonies transformed from a big orange fleecy ones to a small compact reddish ones, or a tightly-packed orange ones without dispersed mycelia with the increase of additives concentration. About the biomass, addition of ammonium acetate at 0.1% increased the biomass of M. ruber M7. With respect to six MPs, all acetate species can enhance pigment production, and ammonium acetate has the most significant impacts. Production of monascin and ankaflavin had the highest increase of 11.7-fold and 14.2-fold in extracellular contents at the 8th day when 0.1% ammonium acetate was supplemented into PDA. Intracellular rubropunctatin and monascorubrin contents gained 9.6 and 6.46-fold at the 8th day, when 0.1% ammonium acetate was added into PDA. And the extracellular contents of rubropunctamine and monascorubramine were raised by 1865 and 4100-fold at the 4th day when M7 grew on PDA with 0.5% ammonium acetate.
Highlights
Monascus species have been used for centuries in the world, especially in China, Japan, and other Asian countries, for the production of many industrially- and medically-important compounds including Monascus pigments (MPs), monacolin K and so on [1,2,3,4,5]
When the media were spiked with acetic acid, the growth of the colony was very different as compared to the normal colony (CK)
When sodium acetate was added in the media at 0.1%, 0.25%, and 0.5% concentration, the results demonstrate that monascorubramine synthesis was improved during the fermentation period
Summary
Monascus species have been used for centuries in the world, especially in China, Japan, and other Asian countries, for the production of many industrially- and medically-important compounds including Monascus pigments (MPs), monacolin K and so on [1,2,3,4,5]. Many compounds are included in MPs [13], but six of them are well known and extensively studied They are two yellow MPs compounds, monascin and ankaflavin, two orange ones, rubropunctatin and monascorubrin, and two red ones, rubropunctamine and monascorubramine [3]. All of these MPs compounds are known for their particular role in human body as health prompting agents [14,15,16,17,18,19,20,21,22]. All of them are produced by a MPs biosynthesis pathway reported in different species
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