Pigment bioproduction by Monascus purpureus using corn bran, a byproduct of the corn industry

Biotechnological potential of Monascus: Biological aspects, metabolites of interest, and opportunities for new products

The need to develop more sustainable products and processes qualifies microbial platforms for obtaining products as a highlighted interesting solution. In this context, filamentous fungi that produce biopigments have been emphasized, especially in the development of research, products and industrial applications. Among the different species, the genus Monascus stands out, either because of its popular use in traditional communities or even because of its versatile growth capacity. Indeed, it is able to metabolize different substrates, including agro-industrial wastes and by-products, as well as allowing different cultivation approaches, such as solid-state and submerged fermentation, for the production of biopigments. Its best-known products include biopigments (yellow, orange and red) and diverse secondary metabolites which have proven biological properties and have great potential in food, pharmaceutical and cosmetic formulations. This review presents the biotechnological, biochemical, and innovation potential of fungi from the genus Monascus, encompassing their historical importance, recent studies on cultivation and production of biopigments, beside the potential of this emerging platform for producing microbial biopigments.

Inorganic Selenium Transformation into Organic Selenium by Monascus purpureus

Selenium (Se) is a trace element that plays a crucial role in metabolism; a lack of selenium reduces the body's resistance and immunity, as well as causes other physiological problems. In this study, we aim to identify favorable conditions for improving organic selenium production. The functional microbe Monascus purpureus, which is widely used in food production, was employed to optimize selenium-enriched culture conditions, and its growth mode and selenium-enriched features were investigated. Spectrophotometry, inductively coupled plasma optical emission spectrometry (ICP-OES), and HPLC (High-Performance Liquid Chromatography) were used to determine the effects of various doses of sodium selenite on the selenium content, growth, and metabolism of M. purpureus, as well as the conversion rate of organic selenium. The best culture parameters for selenium-rich M. purpureus included 7.5 mg/100 mL of selenium content in the culture medium, a pH value of 6.8, a culture temperature of 30 °C, and a rotation speed of 180 rpm. Under ideal circumstances, the mycelia had a maximum selenium concentration of approximately 239.17 mg/kg, with organic selenium accounting for 93.45%, monacoline K production reaching 70.264 mg/L, and a secondary utilization rate of external selenium of 22.99%. This study revealed a novel biological route-selenium-rich M. purpureus fermentation-for converting inorganic selenium into organic selenium.

Antioxidant and in vitro cosmeceutical activities of chestnut inner shell fermented by Monascus kaoliang

Chestnut inner shell (CIS) was fermented at 30 °C for 12 day using Monascus kaoliang, either in solid or submerged state, and alcohol extracts (70% ethanol) of the fermented CIS were examined for their antioxidant (total phenol content and diphenylpicrylhydrazyl radical scavenging activity) and in vitro cosmeceutical activities (tyrosinase and elastase inhibitory activities). Both activities were significantly increased by the M. kaoliang-fermentation, more apparently by submerged fermentation (SMF) than by solid-state fermentation (SSF). The cosmeceutical activity reached its maximum value on the 3rd day of fermentation. The residual amounts of phenolic acids and catechins in the CIS extracts were increased by the fermentation, up to 395.0 and 344.3 µg/g, respectively. More phenolic acids were produced by SMF than SSF, whereas more catechins were produced by SSF than SMF. Therefore, SMF using M. kaoliang was an efficient process for the utilization of CIS as a source of cosmeceuticals.

Characterization of the Red Biochromes Produced by the Endophytic Fungus Monascus purpureus CPEF02 with Antimicrobial and Antioxidant Activities

Food acceptability and appeal are significantly influenced by colour. Harmful effects associated with synthetic colorants are well established, and research is currently focused on developing natural, synthetic chemical-free substitutes from fungal sources, with broad applications in food, medicine, textiles and agriculture. Additionally, the market’s dearth of natural red colour substitutes requires the creation of novel red pigment alternatives from secure and scalable sources. The goal of the current research was to establish new endophytic marine fungi that are naturally occurring bio-sources of the red pigment. Based on its profuse extracellular red pigment-producing capacity, the fungus CPEF02 was selected and identified as Monascus purpureus CPEF02 via internal transcribed spacer (ITS) sequences and phylogenetic analysis. The chemical moieties of the pigmented extracts were identified by liquid chromatography-high resolution mass spectrometry (LC-HRMS). The optimal culture conditions for maximum pigment production were investigated by surveying various media compositions. The methanolic fungal colourant extract was shown to have substantial antibacterial and antifungal activities against anthropogenic pathogens, Staphylococcus aureus (MTCC 1430), methicillin-resistant Staphylococcus aureus (ATCCBAA811), Salmonella typhimurium (MTCC 3241) and Vibrio cholerae (N16961) at a 100 µg/mL concentration and at a 1 mg/mL concentration for Alternaria solani (ITCC 4632) and Rhizoctonia solani (AG1-IA). This extract also exhibited antioxidant activity against the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical with an IC50 of 14.42 µg/mL and a Trolox equivalent antioxidant capacity of 0.571 µM Trolox/µg of the methanolic colourant extract. The findings suggested that M. purpureus’s pigment could be a source of an industrially useful natural red colourant.

Solid-state fermentation of Saba banana peel for pigment production by Monascus purpureus

Eco-friendly natural pigment demand has ever-increasing popularity due to health and environmental concerns. In this context, the aim of this study was to evaluate the feasibility use of Saba banana peel as low-cost fermentable substrate for the production of pigments, xylanase and cellulase enzymes by Monascus purpureus. Among the strains tested, M. purpureus TISTR 3385 produced pigments better and had higher enzyme activities. Under the optimal pigment-producing conditions at the initial moisture content of 40% and initial pH of 6.0, the pigments comprising yellow, orange, and red produced by the fungi were achieved in the range of 0.40-0.93 UA/g/day. The maximum xylanase and cellulase activities of 8.92 ± 0.46 U/g and 4.72 ± 0.04 U/g were also obtained, respectively. More importantly, solid-state fermentation of non-sterile peel could be achieved without sacrificing the production of the pigments and both enzymes. These indicated the potential use of the peel as fermentable feedstock for pigment production by the fungi and an environmental-friendly approach for sustainable waste management and industrial pigment and enzyme application.

Mannitol-Based Media and Static pH Are Efficient Conditions for Red Pigment Production from Monascus purpureus ATCC 36928 in Submerged Culture

Fungi of the Monascus species are used in Asia for the production of fermented foods, mainly due to the ability of these fungi to produce secondary metabolites such as pigments. Due to the growing discussion about the use of synthetic dyes and the fact that their ingestion is associated with harm to human health, studies have sought to replace these dyes using natural pigments, and new alternatives for the production of these natural pigments have been presented. In this context, Monascus pigments are a viable alternative for application in the food industry. This study aimed to evaluate different main carbon sources and pH conditions in the red pigment production of Monascus sp. We found that mannitol, when used as the only carbon source, stimulated the production of extracellular red pigment, reaching a concentration of 8.36 AU in 48 h, while glucose and sucrose reached concentrations of 1.08 and 1.34 AU, respectively. Cultivation in a bioreactor using mannitol showed great potential for optimizing pigment production and obtaining a high concentration of extracellular pigment in a short time, reaching a concentration of 25 AU in 60 h of cultivation. The change in pH altered the production of extracellular red pigment in a culture medium containing mannitol as a carbon source, demonstrating less potential than the use of static pH during cultivation in a bioreactor. Mannitol proved to be an efficient carbon source for M. pupureus under static pH conditions for both flask and benchtop bioreactor cultivation.

Increased Water-Soluble Yellow Monascus Pigment Productivity via Dual Mutagenesis and Submerged Repeated-Batch Fermentation of Monascus purpureus

Monascus pigments (MPs) have been used in the food industry for more than 2,000 years and are known for their safety, bold coloring, and physiological activity. MPs are mainly yellow (YMPs), orange (OMPs), and red (RMPs). In this study, a mutant strain Monascus purpureus H14 with high production of water-soluble YMPs (WSYMPs, λ_max at 370 nm) was generated instead of primary YMPs (λ_max at 420 nm), OMPs (λ_max at 470 nm), and RMPs (λ_max at 510 nm) produced by the parent strain M. purpureus LQ-6 through dual mutagenesis of atmospheric and room-temperature plasma and heavy ion beam irradiation (HIBI), producing 22.68 U/ml extracellular YMPs and 10.67 U/ml intracellular YMPs. WSYMP production was increased by 289.51% in optimal conditions after response surface methodology was applied in submerged fermentation. Application of combined immobilized fermentation and extractive fermentation improved productivity to 16.89 U/ml/day, 6.70 times greater than with conservative submerged fermentation. The produced WSYMPs exhibited good tone stability to environmental factors, but their pigment values were unstable to pH, light, and high concentrations of Ca²⁺, Zn²⁺, Fe²⁺, Cu²⁺, and Mg²⁺. Furtherly, the produced exYMPs were identified as two yellow monascus pigment components (monascusone B and C₂₁H₂₇NO₇S) by UHPLC-ESI-MS. This strategy may be extended to industrial production of premium WSYMPs using Monascus.

Utilization of low-cost agricultural by-product rice husk for Monascus pigments production via submerged batch-fermentation

BACKGROUND

Monascus pigments (MPs) produced by the genus Monascus, have been utilized for more than 2000 years in the food industry. In the present study, by submerged batch-fermentation (SBF), we were able to obtain a mutant strain with a high tolerance of inhibitory compounds generated from rice husk hydrolysate, allowing the production of MPs.

RESULTS

The mutant strain, M. Purpureus M523 with high rice husk hydrolysate tolerance was obtained using the atmospheric and room temperature plasma (ARTP) screening system, producing 39.48 U mL^-1 extracellular total MPs (yellow and orange MPs), using non-detoxified rice husk diluted sulfuric acid hydrolysate (RHSAH) as the carbon source in SBF. Extracellular MPs (exMPs) production was enhanced to 72.1 and 80.7 U mL^-1 in supplemented SBF (SSBF) and immobilized fermentation (IF) using non-detoxified RHSAH, with productivities of 0.16 and 0.37 U mL^-1  h^-1 , respectively. In addition, our findings revealed that despite having a high RHSAH tolerance, the mutant strain was unable to degrade phenolic compounds. Furthermore, we discovered that inhibitory compounds, including furfural (Fur) and 5'-hydroxymethyl furfural (5'-HMF), not only inhibit MP biosynthesis, but also regulate the conversion of pigment components.

CONCLUSION

The low-cost agricultural by-product, rice husk, can serve as an efficient substitute for MP production with high productivity via IF by Monascus spp. © 2021 Society of Chemical Industry.

A systematic study of the production of Monacolin K by solid state fermentation of Monascus ruber

Monacolin K is one of the bioactive substances produced by Monascus ruber during fermentation. The multi-factors and their interactions on the effect of solid-state fermentation of Monascus for high yield of monacolin K were attractive to industrial production. A detailed study of 7 single-factor experiments and a series of experiments with Plackette-Burman and Box-Benhnken design, data fitting and modeling, and analyzing the visual 3D response surface plots for investigation of the key factors for Monacolin K production. The results showed that initial moisture (50 ~ 55%) and bran content (4.5 ~ 5.5%) as the key factors of transport for nutrients and oxygen during the solid-state fermentation (SSF) process of Monascus. Under the optimal conditions, a temperature shifting of the SSF with a higher Monacolin K yield of 14.53 ± 0.16 mg·g^− 1 compared with the content of monacolin K in the commercially available functional red yeast rice of 8 mg g^− 1.

A systematic study for Monacolin K produced by SSF of Monascus ruber.

Initial moisture and bran content are the key factors for the SSF of Monascus.

A proper bran content could suppress the influence of excessive media amount.

Microbial pigments as an alternative to synthetic dyes and food additives: a brief review of recent studies

Synthetic coloring agents have been broadly utilized in several industries such as food, pharmaceuticals, cosmetic and textile. Recent surveys on the potential of teratogenicity and carcinogenicity of synthetic dyes have expressed concerns regarding their use in foods. Worldwide, food industries have need for safe, natural and new colorings to add variety to foods and make them appealing to consumers. Natural colorings not only expand the marketability of the food product, but also add further healthful features such as antibacterial, antioxidant, anticancer and antiviral properties. Novel microbial strains should be explored to meet the increasing global search of natural pigments and suitable techniques must be developed for the marketable production of new pigments, using microbial cultures, viz., fungi, and bacteria. To address the issue of the natural coloring agents, this review presents the recent trends in several studies of microbial pigments, their biological properties and industrial applications.