Improvement of red pigment/citrinin production ratio as a function of environmental conditions by monascus ruber

Utilization of Aspergillus niger for the fermentative production of azaphilone dye in YEPB medium

The current research focuses on the production and optimization of a natural yellowish-brown Azaphilone dye using Aspergillus niger. A variety of culture media were tested to ascertain the best conditions for dye synthesis. The formation of the yellowish-brown dye was confirmed by a color shift in the reaction mixture, and UV-Vis spectroscopy detected the dye at 450 nm. Static conditions were found to be more favorable than shaking for higher dye yields, and fed-batch fermentation was more effective than batch fermentation. Maximum dye production was achieved after 28 days of incubation. Factors such as temperature, pH, and inoculum percentage were shown to influence dye synthesis, with the highest production (2.5 ml) occurring at 30 °C, pH 7, and a 3% spore suspension in yeast extract peptone broth (YEPB) medium under static conditions. Gas chromatography-mass spectrometry (GC-MS) analysis validated the presence of Azaphilone dye in the culture filtrate. The dye was successfully applied to a pretreated cotton cloth. These findings advance our understanding of optimizing fungal dye production for sustainable and eco-friendly textile coloration applications. This study appears to be the first of its kind to report azaphilone dye production by A. niger in the YEPB medium.

OVAT Analysis and Response Surface Methodology Based on Nutrient Sources for Optimization of Pigment Production in the Marine-Derived Fungus Talaromyces albobiverticillius 30548 Submerged Fermentation

Pigment production from filamentous fungi is gaining interest due to the diversity of fungal species, the variety of compounds synthesized, and the possibility of controlled massive productions. The Talaromyces species produce a large panel of metabolites, including Monascus-like azaphilone pigments, with potential use as natural colorants in industrial applications. Optimizing pigment production from fungal strains grown on different carbon and nitrogen sources, using statistical methods, is widespread nowadays. The present work is the first in an attempt to optimize pigments production in a culture of the marine-derived T. albobiverticillius 30548, under the influence of several nutrients sources. Nutrient combinations were screened through the one-variable-at-a-time (OVAT) analysis. Sucrose combined with yeast extract provided a maximum yield of orange pigments (OPY) and red pigments (RPY) (respectively, 1.39 g/L quinizarin equivalent and 2.44 g/L Red Yeast pigment equivalent), as well as higher dry biomass (DBW) (6.60 g/L). Significant medium components (yeast extract, K₂HPO₄ and MgSO₄·7H₂O) were also identified from one-variable-at-a-time (OVAT) analysis for pigment and biomass production. A five-level central composite design (CCD) and a response surface methodology (RSM) were applied to evaluate the optimal concentrations and interactive effects between selected nutrients. The experimental results were well fitted with the chosen statistical model. The predicted maximum response for OPY (1.43 g/L), RPY (2.59 g/L), and DBW (15.98 g/L) were obtained at 3 g/L yeast extract, 1 g/L K₂HPO₄, and 0.2 g/L MgSO₄·7H₂O. Such optimization is of great significance for the selection of key nutrients and their concentrations in order to increase the pigment production at a pilot or industrial scale.

Agro-industrial residues for the production of red biopigment by Monascus ruber: rice flour and sugarcane molasses

Three culture media were studied for red pigment production by Monascus ruber in submerged cultivation: rice flour (20 g L^-1), sugarcane molasses (30 g L^-1), and, finally, molasses + rice flour (10 g L^-1+10 g L^-1); all culture media were added of 5 g L^-1 glycine as nitrogen source. Rice flour showed pigment production of 7.05 UA_510nm and molasses 5.08 UA_510nm, and the mixture of rice flour and molasses showed the best result of 16.38 UA_510nm. Molasses culture presented good results for cell biomass production of 11.09 g L^-1. With these results, it was observed that one substrate presented good pigment production (rice flour) and another attained better results for cell biomass growth (molasses), and a third medium containing 10 g L^-1 of rice flour + 10 g L^-1 of molasses was formulated. The results for this mixture showed satisfactory results, with global pigment productivity of 0.097 UA_510nm h^-1 and maximum productivity rate of 0.17 UA_510nm h^-1. The high production and productivity obtained for the mixture of rice flour and molasses indicated that the production of red pigment by submerged fermentation, using the mixture of these low-cost culture media, may be promising in terms of commercial production.

Addition of genistein to the fermentation process reduces citrinin production by Monascus via changes at the transcription level

Monascus, which is traditionally used in various Asian industries, produces several secondary metabolites during the fermentation process, including citrinin, a toxin whose impact limits the development of the Monascus industry. We have previously found that the addition of 2.0 g/L genistein to Monascus medium reduces citrinin production by approximately 80%. Here, we explored the molecular mechanisms whereby genistein affects citrinin production. We sequenced the Monascus genome and performed transcriptome analysis on genistein-treated and -untreated groups. Comparison between the two groups showed 378 downregulated and 564 upregulated genes. Among the latter, we further examined the genes related to citrinin biosynthesis and quantified them using quantitative real-time polymerase chain reaction (qRT-PCR). Genes orf5, pksCT, orf3, orf1, orf6, and ctnE were significantly downregulated, demonstrating that genistein addition indeed affects citrinin synthesis. Our results may lay the groundwork for substantial improvements in the Monascus fermentation industry.

Production and Characterization of Anti-Inflammatory Monascus Pigment Derivatives

The prevention and treatment of chronic inflammation using food-derived compounds are desirable from the perspectives of marketing and safety. Monascus pigments, widely used as food additives, can be used as a chronic inflammation treatment. Orange Monascus pigments were produced by submerged fermentation in a 5 L bioreactor, and multiple orange Monascus pigment derivatives with anti-inflammatory activities were synthesized using aminophilic reaction. A total of 41 types of pigment derivatives were produced by incorporating amines and amino acids into the orange pigments. One derivative candidate that inhibited nitric oxide (NO) production in Raw 264.7 cells and exhibited low cell cytotoxicity was identified via in vitro assay. The 2-amino-4 picoline derivative inhibited NO production of 48.4%, and exhibited cell viability of 90.6%. Expression of inducible NO synthase, an important enzyme in the NO synthesis pathway, was suppressed by such a derivative in a dose-dependent manner. Therefore, this derivative has potential as a functional food colorant with anti-inflammatory effects.

Effects of some flavonoids on the mycotoxin citrinin reduction by Monascus aurantiacus Li AS3.4384 during liquid-state fermentation

Monascus can produce many beneficial metabolites; however, it can simultaneously also produce citrinin, which seriously limits its application. Therefore, reducing the production of citrinin is of great interest. Herein, Monascus aurantiacus Li AS3.4384 (MAL) was used to optimize the liquid-state fermentation process and investigate the effects of genistein and other flavonoids on citrinin, pigments, and biomass of MAL. Results showed that citrinin decreased by 80%, pigments and biomass increased by approximately 20% in 12 days with addition of 20.0 g/L rice powder as a carbon source and 2.0 g/L genistein during shaking liquid-state fermentation. Further, genistein, daidzein, luteolin, apigenin, quercetin, baicalein, kaempferol myricetin, and genistin exerted different effects on citrinin production by MAL, with genistein causing the highest reduction in citrinin production during liquid-state fermentation, possibly due to the presence of C5-OH, C4′-OH, and C7-OH. Therefore, genistein can be added to the fermentation process of Monascus to reduce citrinin.

Salinity and Temperature Influence Growth and Pigment Production in the Marine-Derived Fungal Strain Talaromyces albobiverticillius 30548

Marine-derived fungi that inhabit severe changing environments have gained increasing interest for their ability to produce structurally unique natural products. Fungi belonging to the Talaromyces and the close Penicillium genera are among the most promising microbes for bioactive compound production, including colored metabolites. Coupling pigment producing capability with bioactive effectiveness would be a valuable challenge in some specific fields such as dyeing, cosmeceutical, or food industries. In this sense, Talaromyces albobiverticillius 30548, a red pigment producing strain, has been isolated from the marine environment of Reunion Island, Indian Ocean. In this research, we analyzed the effect of temperatures (21⁻27 °C) and salinity levels (0⁻9%) on fungal growth and pigment production. Maximum pigment yield was obtained in non-salted media, when cultured at 27 °C after 10 days of submerged fermentation in PDB. However, maximum dry biomass production was achieved at stressed condition with 9% sea salts concentrated media at the same temperature. The results indicate that salinity of the culture media positively influences the growth of the biomass. Inversely, pigment production decreases with increase in salinity over 6%. Color coordinates of secreted pigments were expressed in CIELAB color system. The hue angles (h°) ranged from red to yellow colors. This indicated that the color distribution of fungal pigments depends on the salinity in the culture media. This study emphasizes the impact of abiotic stress (salt and temperature) on the growth and metabolome of marine-derived fungal strains.

Monascus: a Reality on the Production and Application of Microbial Pigments

Monascus species can produce yellow, orange, and red pigments, depending on the employed cultivation conditions. They are classified as natural pigments and can be applied for coloration of meat, fishes, cheese, beer, and pates, besides their use in inks for printer and dyes for textile, cosmetic, and pharmaceutical industries. These natural pigments also present antimicrobial activity on pathogenic microorganisms and other beneficial effects to the health as antioxidant and anticholesterol activities. Depending on the substrates, the operational conditions (temperature, pH, dissolved oxygen), and fermentation mode (state solid fermentation or submerged fermentation), the production can be directed for one specific color dye. This review has a main objective to present an approach of Monascus pigments as a reality to obtaining and application of natural pigments by microorganisms, as to highlight properties that makes this pigment as promising for worldwide industrial applications.

Improved Production and Antitumor Properties of Triterpene Acids from Submerged Culture of Ganoderma lingzhi

Triterpene acids (TAs) are the major bioactive constituents in the medicinal fungus Ganoderma lingzhi. However, fermentative production of TAs has not been optimized for commercial use, and whether the TAs isolated from G. lingzhi submerged culture mycelia possess antitumor activity needs to be further proven. In this study, enhanced TA yield and productivity were attained with G. lingzhi using response surface methodology. The interactions of three variables were studied using a Box-Benhnken design, namely initial pH, dissolved oxygen (DO) and fermentation temperature. The optimum conditions were an initial pH of 5.9, 20.0% DO and 28.6 °C. These conditions resulted in a TA yield of 308.1 mg/L in a 5-L stirred bioreactor. Furthermore, the optimized conditions were then successfully scaled up to a production scale of 200 L, and maximum TA production and productivity of 295.3 mg/L and 49.2 mg/L/day were achieved, which represented 80.9% and 111.5% increases, respectively, compared with the non-optimized conditions. Additionally, the triterpene acid extract (TAE) from G. lingzhi mycelia was found to be cytotoxic to the SMMC-7721 and SW620 cell lines in vitro, and the TAE exhibited dose-dependent antitumor activity against the solid tumor sarcoma 180 in vivo. Chemical analysis revealed that the key active triterpene compounds, ganoderic acid T and ganoderic acid Me, predominated in the extract.

Novel spectrophotometric approach for determination of validamycin A in fermentation of Streptomyces hygroscopicus

Validamycin A (Val-A), produced by Streptomyces hygroscopicus 5008 in industrial fermentation, is one of the most widely used anti-fungal agro-antibiotics in Asia and high performance liquid chromatography (HPLC) assay is usually used to determine the production of Val-A. A new approach to determine Val-A by spectrophotometer is developed. During the fermentation of S. hygroscopicus 5008, a pigment secretion was found along with the Val-A biosynthesis. There was a stable relationship between the concentration of Val-A and spectral absorption (SA) value of this pigment at 450 nm, even in different fermentation cultures or conditions. Using SA value as interior label, a rapid spectrophotometric method for determining Val-A production was established. In comparing Val-A productivity by HPLC method with that by SA method, the relative standard deviation (R.S.D.) was 0.007 (less than 0.05, no variation) and the conditional probability [Pr(T < t)] was 0.3491 (greater than 0.05, no difference) at the optimal time point of Val-A fermentation, which demonstrated SA method was as stable and accurate as standard HPLC method. It was applied successfully to finding positive strains with high Val-A productivity and short fermentation time. SA assay is an accurate and cost-effective method for measuring Val-A and screening high-producing strains, and this work provides a new insight for rapid quantitative analysis of antibiotics in fermentation of pigment-producing strains.

Influence of Light Intensity on Growth and Pigment Production by Monascus ruber in Submerged Fermentation

To reduce environmental problems caused by glycerine accumulation and to make the production of biodiesel more profitable, crude glycerin without treatment was used as substrate for obtaining higher value-added bioproducts. Monascus ruber is a filamentous fungus that produces pigments, particularly red ones, which are used for coloring foods (rice wine and meat products). The interest in developing pigments from natural sources is increasing due to the restriction of using synthetic dyes. The effects of temperature, pH, microorganism morphology, aeration, nitrogen source, and substrates have been studied in the cultivation of M. ruber. In this work, it was observed that light intensity is also an important factor that should be considered for understanding the metabolism of the fungus. In M. ruber cultivation, inhibition of growth and pigment production was observed in Petri dishes and blaffed flasks exposed to direct illumination. Growth and pigment production were higher in Petri dishes and flasks exposed to red light and in the absence of light. Radial growth rate of M. ruber in plates in darkness was 1.50 mm day(-1) and in plates exposed to direct illumination was 0.59 mm day(-1). Maximum production of red pigments (8.32 UA) and biomass (8.82 g L(-1)) were obtained in baffled flasks covered with red film and 7.17 UA of red pigments, and 7.40 g L(-1) of biomass was obtained in flasks incubated in darkness. Under conditions of 1248 lux of luminance, the maximum pigment production was 4.48 UA, with production of 6.94 g L(-1) of biomass, indicating that the fungus has photoreceptors which influence the physiological responses.

Production of citrinin-free Monascus pigments by submerged culture at low pH

Microbial fermentation of citrinin-free Monascus pigments is of great interest to meet the demand of food safety. In the present work, the effect of various nitrogen sources, such as monosodium glutamate (MSG), cornmeal, (NH4)₂SO₄, and NaNO₃, on Monascus fermentation was examined under different initial pH conditions. The composition of Monascus pigments and the final pH of fermentation broth after Monascus fermentation were determined. It was found that nitrogen source was directly related to the final pH and the final pH regulated the composition of Monascus pigments and the biosynthesis of citrinin. Thus, an ideal nitrogen source can be selected to control the final pH and then the citrinin biosynthesis. Citrinin-free orange pigments were produced at extremely low initial pH in the medium with (NH4)₂SO₄ or MSG as nitrogen source. No citrinin biosynthesis at extremely low pH was further confirmed by extractive fermentation of intracellular pigments in the nonionic surfactant Triton X-100 micelle aqueous solution. This is the first report about the production of citrinin-free Monascus pigments at extremely low pH.

Monascus pigments

Monascus pigments (MPs) as natural food colorants have been widely utilized in food industries in the world, especially in China and Japan. Moreover, MPs possess a range of biological activities, such as anti-mutagenic and anticancer properties, antimicrobial activities, potential anti-obesity activities, and so on. So, in the past two decades, more and more attention has been paid to MPs. Up to now, more than 50 MPs have been identified and studied. However, there have been some reviews about red fermented rice and the secondary metabolites produced by Monascus, but no monograph or review of MPs has been published. This review covers the categories and structures, biosynthetic pathway, production, properties, detection methods, functions, and molecular biology of MPs.

Effect of amino acids on red pigments and citrinin production in Monascus ruber

Amino acids were used as sole nitrogen sources to examine their effects on the production of water-soluble red pigments and citrinin by Monascus ruber ATCC 96218 cultivated on chemically defined media. In general, when glycine, tyrosine, arginine, serine, or histidine were used as sole nitrogen sources, they favored the production of red pigments, and restricted the synthesis of the mycotoxin. In contrast, the production of citrinin was enhanced in media supplemented with either glutamate, alanine, or proline. Histidine was found to be the most valuable amino acid as it resulted in the highest production of red pigments and almost completely eliminated the formation of mycotoxin.

Development of Monascus fermentation technology for high hypolipidemic effect

Monascus species has been used as the traditional food fungus in Eastern Asia for several centuries. Monascus-fermented products are gradually developed as the popular functional food for the prevention of cardiovascular disease, but we know that culture condition affects the hypolipidemic effect of Monascus-fermented product. In the past, the cholesterol-lowering agent--monacolin K--is regarded as the most important hypolipidemic agent. Two natural yellow pigments--monascin and ankaflavin--are also proven as novel hypolipidemic agents in recent years. However, the hypolipidemic effect of Monascus-fermented product should contribute from monacolin K, monascin, ankaflavin, and other unknown functional ingredients. In addition to hypolipidemic effect, the safety concern of Monascus-fermented product is involved in the levels of mycotoxin--citrinin. The hypolipidemic effect and the production of these functional metabolites or mycotoxin are influenced by many factors such as the choice of culture substrates, carbon and nitrogen source, pH value, extra nutrients, and so on. Therefore, this review focused on the effect of various culture conditions and nutrients on the functional metabolites production, hypolipidemic effect as well as citrinin concentration, and further organized the fermentation technologies used by previous studies for the promotion of hypolipidemic effect and safety.

Red pigment production by Penicillium purpurogenum GH2 is influenced by pH and temperature

The combined effects of pH and temperature on red pigment production and fungal morphology were evaluated in a submerged culture of Penicillium purpurogenum GH2, using Czapek-Dox media with d-xylose as a carbon source. An experimental design with a factorial fix was used: three pH values (5, 7, and 9) and two temperature levels (24 and 34 °C) were evaluated. The highest production of red pigment (2.46 g/L) was reached with a pH value of 5 and a temperature of 24 °C. Biomass and red pigment production were not directly associated. This study demonstrates that P. purpurogenum GH2 produces a pigment of potential interest to the food industry. It also shows the feasibility of producing and obtaining natural water-soluble pigments for potential use in food industries. A strong combined effect (p<0.05) of pH and temperature was associated with maximal red pigment production (2.46 g/L).

Assessment of monacolin in the fermented products using Monascus purpureus FTC5391

Monacolins, as natural statins, form a class of fungal secondary metabolites and act as the specific inhibitors of HMG-CoA reductase. The interest in using the fermented products as the natural source of monacolins, instead of statin drugs, is increasing enormously with its increasing demand. In this study, the fermented products were produced by Monascus purpureus FTC5391 using submerged and solid state fermentations. Two commercial Monascus-fermented products were also evaluated for comparison. Improved methods of monacolins extraction and identification were developed for the assessment of monacolins in the fermented products. Methanol and ethanol were found to be the most favorable solvents for monacolins extraction due to their ability to extract higher amount of monacolin K and higher numbers of monacolin derivatives. Problem related to false-positive results during monacolins identification was solved by adding monacolin lactonization step in the assessment method. Using this improved method, monacolin derivatives were not detected in all Monascus-fermented products tested in this study, suggesting that their hypocholesterolemic effects may be due to other compounds other than monacolins.

Enhanced hypolipidemic effect and safety of red mold dioscorea cultured in deep ocean water

Red mold dioscorea (RMD) produced by Monascus sp. was proven to be a hypolipidemic functional food. Deep ocean water (DOW), that is, water obtained from over 200 m deep in the ocean, was found to promote the growth of fungus via its mineral richness. On the basis of the advantages, this study used 650 m DOW as the culture water to culture Monascus purpuresus NTU 568 and produce the DOW-RMD. The goal of this study is to compare the difference between DOW-RMD and reverse osmosis water-cultured RMD (ROW-RMD) on the hypolipidemic effect. Hyperlipidemic hamsters were fed a high-cholesterol diet and administered various doses of DOW-RMD or ROW-RMD for 8 weeks. After sacrifice, biochemical analyses in serum, liver, and feces were carried out. The results showed that DOW-RMD had a greater effect on lowering cholesterol levels and lipid peroxidation in serum and lipid plaque in heart aorta than ROW-RMD. However, DOW was likely to modulate the Monascus metabolite biosynthesis pathway toward the formation of hypolipidemic yellow pigments (such as monascin and ankaflavin) rather than red pigments and the mycotoxin citrinin. In addition, the DOW with higher Mg(2+) ion was proven to absorb into DOW-RMD; however, the accumulation of Mg(2+) ions should contribute a greater hypolipidemic effect to DOW-RMD. Comprehensively, the DOW-induced metabolism modulation and the ions of DOW were a benefit to the development of safe DOW-RMD with low citrinin levels and high hypolipidemic, antiatherosclerosis, and anti-fatty liver effects.

Exploring the distribution of citrinin biosynthesis related genes among Monascus species

Citrinin, a hepato-nephrotoxic compound to humans, can be produced by the food fermentation microorganisms Monascus spp. In this study, we investigated the distribution of mycotoxin citrinin biosynthesis genes in 18 Monascus strains. The results show that the acyl-transferase and keto-synthase domains of the pksCT gene encoding citrinin polyketide synthase were found in Monascus purpureus, Monascus kaoliang, and Monascus sanguineus. Furthermore, the ctnA gene, a major activator for citrinin biosynthesis, was found in M. purpureus and M. kaoliang, but was absent in M. sanguineus. The orf3 gene encoding oxygenase, located between pksCT and ctnA, was also present in M. purpureus and M. kaoliang. The pksCT gene was highly conserved in M. purpureus, M. kaoliang, and M. sanguineus, while the ctnA and orf3 genes were shown to be highly homologous in M. purpureus and M. kaoliang. In contrast, the PCR and Southern blot analyses suggest that pksCT, ctnA, and orf3 were absent or significantly different in Monascus pilosus, Monascus ruber, Monascus barkeri, Monascus floridanus, Monascus lunisporas, and Monascus pallens. A citrinin-producing phenotype was detected only in M. purpureus and M. kaoliang using high performance liquid chromatography (HPLC). These results clearly indicate that the highly conserved citrinin gene cluster in M. purpureus and M. kaoliang carry out citrinin biosynthesis. In addition, according to the phylogenetic subgroups established with the beta-tubulin gene, the citrinin gene cluster can group the species of Monascus.

Selection of an effective red-pigment producing Monascus pilosus by efficient transformation with aurintricarboxylic acid

The filamentous fungus Monascus pilosus was genetically transformed with a reporter plasmid, pMS-1.5hp, by aurintricarboxylic acid (ATA) treatment to obtain an efficient red-pigment producing mutant. The transformation efficiency of Monascus pilosus was higher with the ATA-treatment than with either a non-restriction-enzyme-mediated integration (REMI) or a REMI method. This valid and convenient random mutagenesis method shows that ATA can be applied in fungi for efficient genetic transformation.

Profiling the Monascus pilosus proteome during nitrogen limitation

Monascus species have the unique ability to economically produce many secondary metabolites. However, the influence of nitrogen limitation on Monascus secondary metabolite production and metabolic performance remains unclear. Varying the carbon/nitrogen (C/N) ratios in the range from 20 to 60 in cultivation of Monascus pilosus by glucose nitrate medium, our resulting data showed that red pigment production was significantly suppressed and more sensitive to nitrogen limitation than cellular biomass growth at a C/N ratio of 60. Using a comparative proteomic approach, combining two-dimensional gel electrophoresis, matrix-assisted laser desorption ionization time-of-flight/time-of-flight liquid chromatography-mass spectrometry, and tandem mass spectrometry, proteins with modified expression in the nitrogen-limited (C/N ratio 60) Monascus filamentous cells were identified. The results revealed that the deregulated proteins identified were involved in amino acid biosynthesis, protein translation, antioxidant-related enzymes, glycolysis, and transcriptional regulation. The results suggested that, under nitrogen limitation-induced suppression of protein translation and of expression of the related energy-generating enzymes, nitrogen limitation induced a switch of metabolic flux from glycolysis to the tricarboxylic acid (TCA) cycle for maintaining cellular energy homeostasis, resulting in repression of the metabolic shift of the polyketide biosynthesis pathway for red pigment production.

Nutritional and engineering aspects of microbial process development

Today we use many drugs produced by microorganisms. However, when these drugs were discovered it was found that the yields were low and a substantial effort had to be put in to develop commercially viable processes. A key part of this endeavor was the studies of the nutritional and the engineering parameters. In this chapter, the basic principles of optimizing the nutritional and engineering aspect of the production process are described with appropriate examples. It was found that two critical components of nutritional medium, carbon and nitrogen source regulated the synthesis of the compounds of interest. Rapidly utilizable carbon source such as glucose supported the growth but led to catabolite repression and alternative carbon sources or methods of addition had to be devised. Inorganic nitrogen sources led to undesirable changes in pH of the medium. Organic nitrogen sources could influence the yields positively or negatively and had to be chosen carefully. Essential nutrients like phosphates often inhibited the synthesis and its concentration had to be maintained below the inhibitory levels. On many occasions, trace nutrients like metal ions and vitamins were found to be critical for good production. Temperature and pH were important environmental variables and their optimum values had to be determined. The media were designed and optimized initially with 'one variable at a time' approach and later with experimental design based on statistics. The latter approach is preferred because it is economical, considers interactions between medium components and allows rapid optimization of the process. The engineering aspects like aeration, agitation, medium sterilization, heat transfer, process monitoring and control, become critical as the process is scaled-up to the production size. Aeration and agitation are probably the most important variables. In many processes dissolved oxygen concentration had to be maintained above a critical value to obtain the best yields. The rheological properties of fermentation broth significantly affect the aeration and mixing efficiency. The removal of heat from the large fermentors can be difficult under certain conditions. However, new designs of impellers, availability of sensors to monitor important physiological and process variables and advent of computers have facilitated successful scale-up of fermentation processes.

Proteome changes in Caco-2 cells treated with Monascus-fermented red mold rice extract

Monascus-fermented red mold rice has been extensively used as a folk medicine for thousands of years. Monascus secondary metabolites, including monacolin K, monascorubrin, and ankaflavin, have been reported to have an antiproliferative effect on cancer cells. However, the cell machinery responsible for the antiproliferation of Monascus-fermented red mold rice treatment in cancer cells remains unclear. A proteomic approach using two-dimensional gel electrophoresis, matrix-assisted laser desorption ionization time-of-flight/time-of-flight mass spectrometry, and tandem mass spectrometry was used to identify proteins with modified expression in Caco-2 cells treated with Monascus-fermented red mold rice extract. A total of 20 proteins were identified with significantly altered expression (P < 0.05) in response to Monascus-fermented red mold rice extract treatment. The deregulated proteins that were identified included heat shock protein 70, protein kinase C epsilon type, clusterin-associated protein 1, and two tumor suppressors (N-chimaerin and calponin-2). Our results suggested the involvement of heat shock protein 70-mediated cytotoxicity in the Caco-2 cells treated with Monascus-fermented red mold rice extract.

Proteome response of Monascus pilosus during rice starch limitation with suppression of monascorubramine production

For centuries, red mold rice has been made by fermentation of cooked rice with Monascus species. However, the influence of different carbon sources on the metabolism of Monascus cells remains unclear. We compared the proteome response of Monascus pilosus to replacement of the rice starch fraction with lactose during cultivation, using two-dimensional gel electrophoresis, matrix-assisted laser desorption-ionization time-of-flight/time-of-flight mass spectrometry, and tandem mass spectrometry to identify the proteins expressed. The results showed that cell growth and monascorubramine pigment formation of M. pilosus were sensitive to rice starch limitation during cultivation. A total of 12 proteins were identified with statistically altered expression in the cells cultivated with lactose. These deregulated proteins were involved in glycolysis, TCA cycle, energy generation, protein folding, and peptide biosynthesis. The possible metabolic flux shifts induced by rice starch limitation were discussed. The results suggested that the suppression of monascorubramine formation could be related to the necessary energy-requiring adaptations executed in response to carbon depletion during rice starch limitation.

Optimization of culture conditions for production of the anti-tubercular alkaloid hirsutellone A by Trichoderma gelatinosum BCC 7579

AIMS

This work aimed to optimize the culture conditions for production of a novel and potent anti-tubercular alkaloid, hirsutellone A, by the saprophytic soil fungus Trichoderma gelatinosum BCC 7579.

METHODS AND RESULTS

The fungus was initially cultured in shake flasks at 25 degrees C in the potato dextrose broth (PDB) supplemented with various carbon and nitrogen sources and mineral salts to select suitable medium for mycelial growth and hirsutellone A production. Cultivation conditions were further optimized by adjusting initial pH and changing temperature levels to maximize the production of hirsutellone A. The optimal condition that increased the production of hirsutellone A from 19.04 mg l(-1), obtained from basal condition, to 610.55 mg l(-1) and reduced the cultivation time from 40 to 6 days was to cultivate in a shaker at 200 rev min(-1) at 25 degrees C in PDB plus 20 g l(-1) soluble starch, 10 g l(-1) peptone and 2.5% (v/v) salt solution with initial pH of 7. Production of hirsutellone A in larger-scale using a 5-l batch fermenter was also completed yielding 958 mg l(-1) of hirsutellone A within 6 days.

CONCLUSIONS

The suitable culture conditions for hirsutellone A production by T. gelatinosum BCC 7579 was the cultivation in 5-l fermenter at 25 degrees C in PDB plus 20 g l(-1) soluble starch, 10 g l(-1) peptone and 2.5% (v/v) salt solution with an initial pH of 7.

SIGNIFICANCE AND IMPACT OF THE STUDY

The production of hirsutellone A in a fermenter to obtain a high yield and reduce an incubation period will become very useful in anti-tubercular drug development process in the future.

Monascus rice products

The fermentation products of Monascus, especially those produced by solid-state fermentation of rice, have been used as food and health remedies for over 1000 years in China. Monascus rice products (MRPs) are currently being used as health foods in the United States and many Asian countries such as Japan, Taiwan, China, Korea, Thailand, the Philippines, and Indonesia. Many studies have shown that Monascus spp. produce commercially viable metabolites, including food colorants, cholesterol-lowering agents, and antibiotics. The most important bioactive compound isolated from Monascus is monacolin K, which is identical to the potent cholesterol-lowering, antiatherosclerotic drug lovastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor. Several species of the genus Monascus also produce citrinin, a mycotoxin harmful to the hepatic and renal systems. Monacolin K and citrinin are polyketide fungal metabolites. The biosynthetic pathways leading to the formation of polyketides, including monacolin K and citrinin, have been elucidated in Aspergillus and Monascus. The concern for safety is, therefore, high for the development of MRPs as health foods. Other attractive applications for MRPs are likely, as supported by recent studies that indicate that MRPs contain other substances (flavonoids, polyunsaturated fats, phytosterols, pyrrolinic compounds, and others) with a wide variety of biological activities and pharmacological potentials. Their effects in lowering blood sugar and triacylglycerol while raising HDL-C are more pronounced than those of monacolin K alone. Beyond cholesterol lowering, MRP may also be an ideal candidate for the treatment of metabolic syndrome.