Inactivation of mrpigH Gene in Monascus ruber M7 Results in Increased Monascus Pigments and Decreased Citrinin with mrpyrG Selection Marker.

Na Xu,Li Li,Fusheng Chen

doi:10.3390/jof7121094

Abstract

Monascus pigments (MPs) have been used as food colorants for several centuries in Asian countries and are currently used around the world via Asian catering. The MPs biosynthetic pathway has been well-illustrated; however, the functions of a few genes including mrpigH in the MPs gene cluster of M. ruber M7 are still unclear. In the current study, mrpigH was disrupted in Δmrlig4ΔmrpyrG, a highly efficient gene modification system, using mrpyrG as a selection marker, and ΔmrpigHΔmrlig4ΔmrpyrG::mrpyrG and ΔmrpigHΔmrlig4ΔmrpyrG have been obtained. Subsequently, their morphologies, biomasses, MPs and citrinin (CIT) production were analyzed, respectively. These results have revealed that the deletion of mrpigH has significant effects on the morphology and growth of M. ruber M7. Moreover, compared with M. ruber M7, the yields of MPs and CIT were drastically increased and decreased in mrpigH mutants, respectively.

Highlights

Monascus species are famous medicinal and edible filamentous fungi used in traditional fermentation in Asian countries, such as China, Japan, and the Korean Peninsula for nearly 2000 years [1,2]
In 2017, Balakrishnan et al predicted that the mppE in M. purpureus KACC encoded a reductase which can decrease orange pigments (OPs) and red pigments (RPs) in the biosynthesis of Monascus pigments (MPs) [8]
Sequence prediction of mrpigH by Softberry’s FGENESH program has revealed that the putative mrpigH gene consists of a 1110 bp open reading frame (ORF) which consists of one exon and encodes 369-amino acids

Summary

Introduction

Monascus species are famous medicinal and edible filamentous fungi used in traditional fermentation in Asian countries, such as China, Japan, and the Korean Peninsula for nearly 2000 years [1,2]. At present, their fermented products, such as Hongqu, called red fermented rice, red yeast rice and red mold rice, are widely used as food additives and nutraceutical supplements worldwide owing to their production of abundant beneficial secondary metabolites (SMs), such as Monascus pigments (MPs), monacolin K (MK) and γ-amino butyric acid (GABA) [1,3]. In 2019, Chen et al guessed that MrPigH might contribute to reducing the carbon double bond of the precursor compounds to the typical yellow pigments (YPs) monascin and ankaflavin [7]

Methods

Results

Conclusion