Monascus Ruber Research Articles

Hydrodynamic cavitation assisted pretreatment of sugarcane bagasse in the presence of yeast cell mass for the production of sugars and their use for biopigments production by Monascus ruber

Hydrodynamic cavitation-assisted pretreatment of sugarcane bagasse tested in the, with the addition of yeast extract. This pretreatment was investigated using a 22 central composite design experiment. A total of 11 experiments were performed. The pretreated biomass was then tested for enzymatic hydrolysis for the sugars production. Various enzymatic loadings (15–20 FPU/g biomass) and concentrations of yeast extract (0.25–1 g/L) were studied during the enzymatic hydrolysis. Optimization of yeast extract insertion was performed to simultaneously facilitate the infusion of cellulolytic enzymes into the pores of the pre-treated bagasse concomitantly inhibiting enzyme absorption caused by residual lignin. The optimized results revealed an 81 % glucan hydrolysis yield and a 78 % xylan hydrolysis yield after the enzymatic hydrolysis under optimized conditions (20 FPU/g and 1 g/L of yeast extract). The hydrolysate rich in sugars derived from carbohydrate polymers and nitrogen sources derived from hydrolysis of yeast cream was assessed for biopigments production by Monascus ruber. The hydrolysate used for M. ruber fermentation showed the production of pigments with 15 AU (absorbance units) for yellow, 15 AU for orange and 20 AU for red after 9 days of fermentation. These results proved the efficiency of using yeast cream as a potential blocking agent of lignin in turn increasing the sugars production and a nitrogen source for the M. ruber for biopigments production from sugarcane bagasse hydrolysate.

Novel nanoconjugates of metal oxides and natural red pigment from the endophyte Monascus ruber using solid-state fermentation

BackgroundAntimicrobial resistance has emerged as a major global health threat, necessitating the urgent development of new antimicrobials through innovative methods to combat the rising prevalence of resistant microbes. With this view, we developed three novel nanoconjugates using microbial natural pigment for effective application against certain pathogenic microbes.ResultsA natural red pigment (RP) extracted from the endophyte Monascus ruber and gamma rays were applied to synthesize RP-ZnO, RP-CuO, and RP-MgO nanoconjugates. The synthesized nanoconjugates were characterized by different techniques to study their properties. The antimicrobial potential of these nanoconjugates was evaluated. Moreover, the antibiofilm, protein leakage, growth curve, and UV light irradiation effect of the synthesized nanoconjugates were also studied. Our results confirmed the nano-size, shape, and stability of the prepared conjugates. RP-ZnO, RP-CuO, and RP-MgO nanoconjugates showed broad antimicrobial potential against the tested bacterial and fungal pathogens. Furthermore, the RP-ZnO nanoconjugate possessed the highest activity, followed by the RP-CuO against the tested microbes. The highest % inhibition of biofilm formation by the RP-ZnO nanoconjugate. Membrane leakage of E. coli and S. aureus by RP-ZnO nanoconjugate was more effective than RP-MgO and RP-CuO nanoconjugates. Finally, UV light irradiation intensified the antibiotic action of the three nanoconjugates and RP-ZnO potential was greater than that of the RP-MgO, and RP-CuO nanoconjugates.ConclusionThese findings pave the way for exploiting the synthesized nanoconjugates as potential materials in biomedical applications, promoting natural, green, and eco-friendly approaches.

Enhancing bioprocessing of red pigment from immobilized culture of gamma rays mutant of the endophytic fungus Monascus ruber SRZ112

Considerable attention has been paid to exploring the biotechnological applications of several Monascus sp. for pigment production. In this study, our focus is on enhancing the bioprocessing of red pigment (RP) derived from the endophytic fungus Monascus ruber SRZ112. To achieve this, we developed a stable mutant strain with improved productivity through gamma irradiation. This mutant was then employed in the immobilization technique using various entrapment carriers. Subsequently, we optimized the culture medium for maximal RP production using the Response Surface Methodology. Finally, these immobilized cultures were successfully utilized for RP production using a semi-continuous mode of fermentation. After eight cycles of fermentation, the highest RP yield by immobilized mycelia reached 309.17 CV mL−1, a significant increase compared to the original titer. Importantly, this study marks the first report on the successful production of Monascus RP in a semi-continuous mode using gamma rays’ mutant strain, offering prospects for commercial production.

Polygonati rhizoma fermentation by Monascus ruber and evaluation of fermentation products in vitro

This study investigated the conditions for polygonati rhizoma (PR) fermentation by Monascus ruber and the lipid-lowering activity of the resulting product. Monascus ruber was used for the solid-state fermentation of PR, and the response surface method was used to optimize the fermentation culture medium parameters. The optimal fermentation system yielded a maximum monacolin K concentration of 21.82 ± 0.34 mg/g. The fermentation conditions were as follows: 12.5 mmol/kg of L-glutamic acid, 0.64 mmol/kg of cyclic adenosine monophosphate, 3.0 wt% of yeast extract powder, a fermentation period of 15 days, and a fermentation temperature of 30 ℃. The binding capacities of unfermented PR, “Nine-Steam-Nine-Bask” processed Polygonati rhizoma (NPR), and Monascus ruber solid-state fermented polygonati rhizoma (MPR) to sodium cholate, sodium taurocholate, and sodium glycolate were determined. MPR showed a stronger bile acid-binding capacity than unfermented PR. In addition, MPR exhibited the highest cholesterol inhibitory capacity of 51.43±1.41 %. Thus, MPR can be used as a potential antilipemic agent with potent hypolipidemic effects.

Modeling the Thermal Inactivation of Monascus ruber Ascospores Isolated from Green Olive (Arauco Cultivar) Storage Brine: An Alternative Strategy to Reduce Antifungal Chemical Agents.

Monascus ruber is an important fungus that causes spoilage in table olives, resulting in the darkening of the brine, the softening of the fruit, increased pH, and apparent mycelial growth. This study aimed to evaluate this resistance, providing a model to determine the optimal processing conditions for mitigating fungal contamination and prolonging shelf life without antifungal agents while optimizing pasteurization to reduce energy consumption. The resistance in brine (3.5% NaCl; pH 3.5) from Arauco cultivar green olives imported from Argentina was assessed. Four predictive models (log linear, log linear + shoulder, log linear + tail, log linear + shoulder + tail) estimated kinetic parameters for each survival curve. Log linear + shoulder + tail provided the best fit for 70 °C and 75 °C, with low RMSE (0.171 and 0.112) and high R2 values (0.98 and 0.99), respectively, while the log linear model was used for 80 °C. Decimal reduction times at 70, 75, and 80 °C were 24.8, 5.4, and 1.6 min, respectively, with a z-value of 8.2 °C. The current regulatory processes are insufficient to eliminate M. ruber at requisite levels, considering reduced antifungal agents.

Mrvam7, a conserved SNARE gene involved in vacuolar fusion, is required for development and secondary metabolism in Monascus ruber M7

Vam7 (vacuolar morphogenesis 7), a Qc-soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) that mediates vacuolar fusion, is involved in vacuolar morphogenesis, vegetative growth, sexual and asexual reproduction, and compartmentalized biosynthesis of secondary metabolites in various filamentous fungi. In this study, the homolog of vam7 gene, mrvam7, in Monascus ruber M7 was functionally characterized through gene modification and transcriptome analysis. The results showed that the mrvam7 complementation and overexpression strains exhibited phenotypic similarities to M. ruber M7, whereas the mrvam7 null strain exhibited fragmented vacuoles, slowed growth and diminished sexual and asexual sporulation. Furthermore, the mrvam7 knockout strain displayed a notable increase in citrinin production alongside a significant decrease in Monascus pigments production. Transcriptome data revealed that the deletion of mrvam7 altered the expression levels of several genes involved in sexual and asexual reproduction, carbon and nitrogen source utilization, and secondary metabolites biosynthetic gene clusters. Collectively, these findings underscore the critical role of mrvam7-mediated vacuolar fusion in growth, development, and the compartmentalized biosynthesis and distribution of secondary metabolites in M ruber M7. This study provides novel insights into the mechanisms underlying of compartmentalized secondary metabolites biosynthesis in Monascus species.

Insight into selenium biofortification and the selenite metabolic mechanism of Monascus ruber M7

Monascus species are functional fermentation fungi with great potential for selenium (Se) supplementation. This study investigated the effects of Se bio-fortification on the growth, morphology, and biosynthesis of Monascus ruber M7. The results demonstrated a significant increase in the yield of orange and red Monascus pigments (MPs) in red yeast rice (RYR) by 38.52% and 36.57%, respectively, under 20 μg/mL of selenite pressure. Meanwhile, the production of citrinin (CIT), a mycotoxin, decreased from 244.47 μg/g to 175.01 μg/g. Transcriptome analysis revealed significant upregulation of twelve genes involved in MPs biosynthesis, specifically MpigE, MpigF, and MpigN, and downregulation of four genes (mrr3, mrr4, mrr7, and mrr8) associated with CIT biosynthesis. Additionally, three genes encoding cysteine synthase cysK (Log2FC = 1.6), methionine synthase metH (Log2FC = 2.2), and methionyl-tRNA synthetase metG (Log2FC = 1.8) in selenocompound metabolism showed significantly upregulated. These findings provide insights into Se biotransformation and metabolism in filamentous fungi.

Effects of MrwetA on Sexual Reproduction and Secondary Metabolism of Monascus ruber M7 Based on Transcriptome Analysis.

wetA, one of the conidiation center regulatory genes in many filamentous fungi, plays an important role in promoting asexual spores (conidia) maturation. Our recent research has found that knocking out or overexpressing MrwetA (a homolog of wetA) in Monascus ruber M7 does not affect the development of its asexual spores like other fungi, but both repress the development of its sexual spores (ascospores). However, the mechanism remains unclear. In this study, the function of MrwetA on sexual reproduction and secondary metabolism in M. ruber M7 was confirmed by a complementary experiment. Moreover, the regulatory roles of MrwetA in modulating the expression of genes involved in sexual reproduction, meiosis, and biosynthesis of Monascus pigment and citrinin were analyzed based on the transcriptional data. These results not only contribute to clarifying the regulation of the reproduction and secondary metabolism of Monascus spp., but also to enriching the regulation molecular mechanism of reproduction in filamentous fungi.

Biological transformation of medicine and food homology hawthorn with Monascus ruber to enhance lipid-lowering function

Obesity and hyperlipidemia, chronic diseases resulting from excessive energy intake and abnormal lipid metabolism, respectively, are intricately associated with cardiovascular disease and diabetes and have become global health problems. Monascus ruber (M. ruber), a filamentous fungus with edible properties, produces bio-functional metabolites including a good deal of enzymes. In this study, the effect of the biological transformation of fermented food on obesity and hyperlipidemia, was systematically investigated using the mixture of medicine and food homology (MFH) hawthorn and millet as fermentation substrate. Results showed that fermentation promoted the release of bioactive compounds such as phenolic compounds. Pancreas lipase assay indicated that the inhibition rate and IC50 of free phenolic compounds in fermented MFH food were 70.51% ± 2.59%, and 1.34 mg/mL, respectively. In vitro, the binding rates of free phenolic compounds in fermented MFH food to Sodium cholate (SC), sodium glycinate (SGC) and sodium taurocholate (STC) were 84.99% ± 6.59%, 80.29% ± 6.23%, and 79.68% ± 6.18%. Further, Monascus-fermented hawthorn and millet (MFHM) of fermented MFH food markedly suppressed lipid accumulation in oleic acid (OA)-induced HepG2, with cell triglycerides (TG) and total cholesterol (TC) clearance of 24.31% ± 1.81% and 73.88% ± 2.72%, respectively. These findings implied that the fermentation of a mixture of MFH millet and hawthorn by M. ruber holds promise for reducing obesity and lowering lipid levels, thereby serving as a valuable foundation and reference for future research on the development of multifunctional food products.

Retracted: Impact of Light and Temperature on Growth, Intracellular and Extracellular Pigment, and Lovastatin Yield by Monascus ruber in Synthetic Medium

Retracted: Impact of Light and Temperature on Growth, Intracellular and Extracellular Pigment, and Lovastatin Yield by Monascus ruber in Synthetic Medium

Significant enhancement of edible Monascus azaphilone pigments production via targeted improvement of the expression of histone deacetylase MrHos2

Monascus azaphilone pigments (MonAzPs) are beneficial secondary metabolites secreted by Monascus spp., which have great potentials to be used in industrial fields besides food industry. But there is very little knowledge about their regulatory mechanism, which limits the large-scale production and utilization of MonAzPs. In this study, we firstly studied the effect on MonAzPs production by inhibiting and enhancing histone deacetylase gene hos2 (Mrhos2) expression in Monascus ruber. UPLC detection revealed that inactivation of Mrhos2 dramatically decreased MonAzPs production, while overexpression of Mrhos2 significantly increased MonAzPs production. Transcriptional level analysis shows Mrhos2 regulates expression of MonAzPs biosynthesis genes. Immunoaffinity enrichment assisted mass spectrometry assay reveals deletion of Mrhos2 perturbs lysine acetylation of enzymes in the metabolic pathway of acetyl-CoA and malonyl-CoA. Collectively, transcription activation and protein acetylation modification mediated by MrHos2 are involved in regulating the MonAzPs production, and MrHos2 can be used as a target to increase MonAzPs production.

Draft genome sequence of Monascus ruber strain FM39-7.

In China, certain Monascus ruber strains are traditionally used as edible fungi. We sequenced the genome of M. ruber FM39-7 strain, an isolate from fermented rice. The genome is 25.89 Mb with a G + C content of 48.86%, containing 8485 annotated genes.

Effects of pomelo sponge fermented by Monascus ruber on cholesterol metabolism and intestinal microbiota in high-fat diet mice

The purpose of this study is to produce Monascus ruber fermented pomelo sponge products (MFPS) utilizing low-cost pomelo sponge as a solid-state fermentation substrate, and to investigate the effects of MFPS on cholesterol metabolism and gut microbiota in mice. The study of oral MFPS treatment in high-fat diet mice uncovered that a high dosage of MFPS effectively inhibited the increase of body weight, reduced the accumulation of liver and epididymal fat and improved blood cholesterol metabolism in mice. Interestingly, MFPS consumption enhanced the liver's antioxidant capacity, cleared free radicals. Furthermore, HE staining demonstrated that MFPS effectively repaired liver damage. UPLC-QTOF/MS analysis of liver metabolomics revealed that MFPS intervention exerts a substantial regulatory impact on metabolic pathways encompassing alanine, aspartate and glutamate metabolism, biosynthesis of unsaturated fatty acids, steroid hormone biosynthesis, tryptophan metabolism, glycerophospholipid metabolism, fatty acid degradation, folate biosynthesis, etc. High-throughput sequencing of 16S rRNA unveiled that MFPS mitigated the intestinal microbiota imbalance triggered by a high-fat diet, increasing the abundance of probiotics in the intestine, including Lactobacillus and Bifidobacterium. Therefore, these findings demonstrate that MFPS can improve abnormal cholesterol metabolism and balance intestinal flora, offering valuable insights for developing natural and effective cholesterol-lowering products.

Regulation of the pigment production by changing cellmorphology and gene expression of Monascus ruber in high-sugar synergistic high-salt stress fermentation.

Extreme environment of microbial fermentation is the focus of research, which provides new thinking for the production and application of Monascus pigment. In this work, the high-sugar synergistic high-salt stress fermentation (HSSF) of Monascus pigment was investigated. The Monascus fungus grew well under HSSF conditions with 35g L-1 NaCl and 150g L-1 glucose, and the extracellular yellow pigment and intracellular orange pigment yield in HSSF was 98% and 43% higher than that in conventional fermentation (CF), respectively. Moreover, the mycelial morphology was maintained in a better status with more branches and complete surface structure, indicating good biocatalytic activity for pigment synthesis. Four extracellular yellow pigments (Y1, Y2, Y3, Y4) were transformed into each other, and ratio of the relative content of intracellular orange pigments to yellow pigments (O/Y) significantly (p<0.05) changed. Moreover, the ratio of unsaturated fatty acids to saturated fatty acids (unsaturated/saturated) was significantly (p<0.05) increased, indicating that the metabolism and secretion of intracellular and extracellular pigment might be regulated in HSSF. The pigment biosynthesis genes mppB, mppC, mppD, MpPKS5, and MpFasB2 were up-regulated, whereas the genes mppR1, mppR2, and mppE were down-regulated, suggesting that the gene expression to regulate pigment biosynthesis might be a dynamic change process in HSSF. The HSSF system of MPs is successfully performed to improve the pigment yields. Mycelial morphology is varied to enhanced pigment secretion and gene expression is dynamically regulated to promote pigment accumulation in HSSF.

Production of biopigment by Monascus ruber AUMC 245 under submerged fermentation and its application as colorants of some food products

The goal of the current investigation was to examine the production of red biopigment by Monascus ruber AUMC 245 during submerged fermentation and assess its safety as a bio-colorant in the food sector due to due to only sensory evaluation in food products. The various factors used for the production of red pigments, citrinin, and biomass yield were follows: 20 ℃–40 ℃ of temperature, 4.5–8.5 of pH, carbon and nitrogen sources. The optimum conditions were 30 ℃, pH 6.5, rice, peptone and incubation time for 10 days. The produced biopegment was without mycotoxin (citrinin). So, it is suitable for application in food industry. Kids jelly cola, ice sherbets and luncheon meat were prepared using the red pigments as natural colorant. The tested foods colored by nature biopigment appeared sensory results (90%) as acceptable consuming evaluation. It was not far from the applied industrial chemical one, but it is advantages by safe conditions. In conclusion, we can state that the obtained red pigments are safe to use in food products instead of chemical one.

Valorization of rice husk by hydrothermal processing to obtain valuable bioproducts: Xylooligosaccharides and Monascus biopigment

Rice husk is a readily available residue which can be used for producing bioproducts in a biorefinery context. In this study, the hemicellulose fraction was hydrolyzed in a hydrothermal process to produce xylooligosaccharides (XOS), whereas the cellulosic hydrolysate was used for red pigment production by Monascus ruber Tieghem IOC 2225. The highest XOS (X2-X4) production (24 g per 1 kg of rice husk) was achieved at 180 °C for 68 min in a non-stirred Parr reactor (50 mL). Subsequently, using a stirred parr reactor (1 L) at 180 °C for 60 min, 40 g of XOS (42% of xylobiose, 35% of xylobiose, 13% of xylotriose, 7% of xylotetraose, and 3% of xylopentaose) per 1 kg of rice husk were obtained. The XOS was then purified by using ultrafiltration (UF) with two diafiltration membranes at 6.5 pH, recovering approximately 92% of total XOS. Further purification was conducted with nanofiltration (NF) at 3.8 pH, recovering approximately 86.4% of XOS in the retentate. This process yielded XOS with a purity of 77%. Additionally, the enzymatic process yielded 132 g/kg of sugar, and the hydrolysate was used to produce 2.1 UA490nm of red pigment by fungi after 7 days.

Optimization of L-glutaminase production by Monascus ruber URM 8542 isolated from ice cream industrial effluent.

L-glutaminase is a hydrolytic enzyme with wide biotechnological applications. Mostly, these enzymes are employed in the feed industry for flavor enhancement and acrylamide mitigation. Also, L-glutaminase may have antiviral and antineoplastic effects making it a good choice for pharmaceutical applications. In this study, the strain Monascus ruber URM 8542 was identified through classical and molecular taxonomy using partial sequencing of β-tubulin and calmodulin genes. Subsequently, the optimal culture conditions were evaluated by submerged fermentation (L-glutamine 10g.L- 1) for L-glutaminase excretion. The isolate was identified as M. ruber URM 8542 which showed significant extracellular enzyme production with a yield of 11.4 times in relation to the specific activity of intracellular L-glutaminase. Regarding the optimization experiments, several factors such as L-glutamine concentration, temperature, and pH were compared using a full factorial design (23). The concentrations greater than 1% proved to be significantly better for glutaminase production (R2 = 0.9077). Additionally, the L-glutaminase was optimally active at pH 7.0 and 30 ºC. The L-glutaminase was remarkably stable across an alkaline pH range (7.0-8.0) and had a thermal stability ranging from 30 ºC to 60 ºC for 1h. Taken together, these findings suggest that the L-glutaminase produced by M. ruber is a promising candidate for pharmacological application, although further studies need to be performed. To the best of our knowledge, this is the first report of L-glutaminase production by Monascus ruber.

Enhancement of Monacolin K Production by Intergeneric Hybridization between Monascus purpureus (Arg-) and Monascus ruber (Thi-, Met-) Auxotrophs

This study aims to reconcile industrially suitable strains of higher red pigment producing Monascus purpureus MPA5 and higher Monacolin K producing Monascus ruber MRA7, were tried to fuse for development of increased efficacy of targeted secondary metabolites production. The optimum concentration of protoplast mixture was standardized, before the fusion experiment. The effective fusion was observed with the solution of 30 % PEG 6000, CaCl2.2H2O (0.01 M) and glycine (0.05 M). Colonies of the fusants were segregated using complete medium. The fusants were irradiated under UV- light in LD50 dose. On the basis of non-segregation of colony appearance after repeated subculturing in complete medium, 8 colonies were selected. Finally, one of the stable fusant MF11 grew more rapidly than one of the parental strain M. purpureus MPA5, but not as fast as M. ruber MRA7, were selected and grown on low grade rice as solid substrate for production of metabolites. Production of red pigments, alpha-amylase and acid protease were at intermediate stage between two parental strains but enhancement of Monacolin K was observed. High performance liquid chromatography (HPLC) analysis was revealed that Monacolin K content was increased as much as two and half times than the parents. No fluorescent yellow band was detected in TLC plate, indicating of citrinin negativity of the fusant MF11. It is the first report of enhanced Monacolin K production by a stable fusant of Monascus sp.

Dynamic changes of active substances of rice, Pueraria and yam fermentation by Monascus ruber

Monascus spp., a fungus of medicine food homology, produces various beneficial secondary metabolites such as monacolin K (MK) during fermentation. In this study, the mixed fermentation of Monascus with rice, Pueraria, and yam has been systematically investigated. Single-factor and response surface methodology (RSM) were carried out to maximize MK content, and the optimized fermentation results showed that the content of MK reached 1.40 ± 0.04 mg/g. The optimal fermentation process determined the ratio of 8: 1: 1 for rice, Pueraria, and yam, respectively, the inoculation amount was 106 spores/mL, fermentation time was 15 days. Further analysis of the content of active substance in the fermentation process revealed that the β-glycosidase activity increased, the amylase enzyme activity decreased, the dioscin content decreased by 19.5%, and the diosgenin content increased by 175%, suggesting that there was a dynamic equilibrium relationship among the changes of active substances. This study aims at provide a basis and reference for the research of Monascus fermented foods by medicine food homology raw materials.

Histone deacetylase MrHos3 negatively regulates the production of citrinin and pigments in Monascus ruber.

Monascus spp. can produce a variety of beneficial metabolites widely used in food and pharmaceutical industries. However, some Monascus species contain the complete gene cluster responsible for citrinin biosynthesis, which raises our concerns about the safety of their fermented products. In this study, the gene Mrhos3, encoding histone deacetylase (HDAC), was deleted to evaluate its effects on the production of mycotoxin (citrinin) and the edible pigments as well as the developmental process of Monascus ruber M7. The results showed that absence of Mrhos3 caused an enhancement of citrinin content by 105.1%, 82.4%, 111.9%, and 95.7% at the 5th, 7th, 9th, and 11th day, respectively. Furthermore, deletion of Mrhos3 increased the relative expression of citrinin biosynthetic pathway genes including pksCT, mrl1, mrl2, mrl4, mrl6, and mrl7. In addition, deletion of Mrhos3 led to an increase in total pigment content and six classic pigment components. Western blot results revealed that deletion of Mrhos3 could significantly elevate the acetylation level of H3K9, H4K12, H3K18, and total protein. This study provides an important insight into the effects of hos3 gene on the secondary metabolites production in filamentous fungi.