Elucidation Of The Expression And Role Of Carotenogenic Genes In Astaxanthin Production In A Hyper-Producing Mutant Of Xanthophyllomyces Dendrorhous

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Date
2018-05
Authors
Ang, Fong Sim
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Universiti Sains Malaysia
Abstract
Astaxanthin is a red xanthophyll pigment which is commercially used in aquaculture as feed additive and in pharmaceutical industries due to its strong antioxidant properties. Synthetic astaxantin is limited by its properties, production requirements and also the strict regulations concerning the safety of synthetic chemicals as food additives. This has led to the alternative microbial production of natural astaxanthin. Xanthophyllomyces dendrorhous has desirable properties and commercial value as a dietary source of natural astaxanthin, but it has relatively low content of astaxanthin. Various methods had been applied to improve the astaxanthin yield including optimization of culture conditions, random mutagenesis and genetic engineering. The aim of this study was to generate a stable astaxanthin hyperproducing mutant of X. dendrorhous DSM 5626 (EMS) and N-methyl-N′-nitro-N-nitrosoguanidine (MNNG). The expressions levels and changes of nucleotide sequence of carotenogenic biosynthesis genes were studied by Real-Time PCR and PCR resepectively, and correlated to the carotenoid production. A hyperproducing mutant, M34, was successfully isolated from MNNG mutagenesis through β-ionone screening, with a higher total carotenoid content of 602.36 μg/g compared to 285.71 μg/g in wild type strain, which was a 110.83% increment. Compared to EMS, MNNG treatment led to higher lethality in recipient cells and was more effective in inducing the pigmented mutants with intense red colour and bigger colony indicating higher astaxanthin content and cell growth, with lower rate of reverse mutation.
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Generate a stable astaxanthin hyperproducing mutant , through chemical mutagenesis using ethyl methanesulfonate
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