Investigation Of The Relationship Between The Biosynthise Of Monascus Lipid And Pigments And The Establishment Of Resting-cell Culture System Of Monascus

Few studies of the FA profile of the genus Monscus have been published.C18:1,C18:2,C16:0,C18:0 and C16:1 were identified as the major acids.And some polyunsaturated fatty acids,such as arachidonic acid(ARA),eicosapentaenoic acid(EPA)and docosahexaenoic acid(DHA),were also found among the fatty acids.The same precursor acetyl CoA is utilized for biosynthesis of both Monascus pigments(catalyzed by polyketide)and fatty acids(catalyzed by fatty acid synthase).However,the relationship of Monascus pigments and lipid accumulation have never been discussed,as well as the lipid content of Monascus.In this work,a series of submerged fermentation of Monascus were conducted in the medium of different concentration of MSG,Triton X-100 and different pH.The results indicted that the limited nitrogen concentration and/or low initial pH 2.5 conditions favored the production of intracellular orange pigments and accumulation of microbial lipid(high content reaching to approximately 50% in dry cell weight)by Monascus anka.Interestingly,the content of pigments and the weight of lipid exhibited a positive correlated relationship.Extractive fermentation in nonionic surfactant micelle aqueous solution selectively exported the intracellular Monascus pigments into its extracellular broth,in which the concentration of intracellular pigments was negligible while the extracellular one was enhanced.The extractive fermentation provides a novel strategy for shifting of the metabolic channeling from intracellular lipid accumulation to Monascus pigment production.High pigment concentration,i.e.,approximately 40 AU of extracellular Monascus pigments,was achieved by extractive fermentation at relatively high nonionic surfactant concentration 10 g/l.This phenomenon might be attributed to the nonionic surfactant micelles acting as pigment reservoir by biomimetic of intracellular lipids.Growing cell submerged culture is usually applied for fermentation of intracellular orange Monascus pigments,in which accumulation of Monascus pigments is at least partially associated to cell growth.In the present work,extractive fermentation in a nonionic surfactant micelle aqueous solution was utilized as a strategy for releasing of intracellular Monascus pigments.Those mycelia with low content of intracellular Monascus pigments were utilized as biocatalyst in resting cell submerged culture.By this means,resting cell submerged culture for production of orange Monascus pigments was carried out successfully in the nonionic surfactant micelle aqueous solution,which exhibited some advantages comparing with the corresponding conventional growing cell submerged culture,such as non-sterilization operation,high cell density(24 g/l DCW)leading to high productivity(14 AU of orange Monascus pigments at 470 nm per day),and recycling of cells as biocatalyst leading to high product yield(approximately 1 AU of orange Monascus pigments at 470 nm per gram of glucose)based on energy metabolism.