Monascus Ruber Research Articles

Application of neural networks as a non-linear modelling technique in food mycology

Fungal growth leads to spoilage of food and animal feeds and to formation of mycotoxins and potentially allergenic spores. There is a growing interest in modelling microbial growth as an alternative to time-consuming, traditional, microbiological enumeration techniques. Several statistical models have been reported to describe the growth of different micro-organisms however the nature of neural networks, as highly non-linear approximator schemes, considers them as an alternative methodology. The application of neural networks in predictive microbiology is presented in this paper. This technique was used to build up a model of the joint effect of water activity, pH level and temperature to predict the maximum specific growth rate of the ascomycetous fungus Monascus ruber. Neural network and polynomial models were compared against the experimental data using six statistical indices namely, coefficient of determination (R^2), root mean square error (RMSE), mean relative percentage error (MRPE), mean absolute percentage error (MAPE), standard error of prediction (SEP), bias (Bf) and accuracy (Af) factors. Graphical plots were also used for model comparison. The performance of the learning-based systems provide encouraging results while sensitivity analysis showed that from the three environmental factors the most influential on fungal growth was temperature, followed by water activity and pH to a lesser extend. Neural networks offer an alternative and powerful technique to model microbial kinetic parameters and could thus become an additional tool in predictive mycology.

Solid-state cultivation of Monascus ruber under different bioreactor scales

Solid-state cultivation of Monascus ruber under different bioreactor scales

Modelling fungal growth using radial basis function neural networks: The case of the ascomycetous fungus Monascus ruber van Tieghem

A radial basis function (RBF) neural network was developed and evaluated against a quadratic response surface model to predict the maximum specific growth rate of the ascomycetous fungus Monascus ruber in relation to temperature (20–40 °C), water activity (0.937–0.970) and pH (3.5–5.0), based on the data of Panagou et al. [Panagou, E.Z., Skandamis, P.N., Nychas, G.-J.E., 2003. Modelling the combined effect of temperature, pH and aw on the growth rate of M. ruber, a heat-resistant fungus isolated from green table olives. J. Appl. Microbiol. 94, 146–156]. Both RBF network and polynomial model were compared against the experimental data using five statistical indices namely, coefficient of determination ( R 2), root mean square error (RMSE), standard error of prediction (SEP), bias ( B f) and accuracy ( A f) factors. Graphical plots were also used for model comparison. For training data set the RBF network predictions outperformed the classical statistical model, whereas in the case of test data set the network gave reasonably good predictions, considering its performance for unseen data. Sensitivity analysis showed that from the three environmental factors the most influential on fungal growth was temperature, followed by water activity and pH to a lesser extend. Neural networks offer an alternative and powerful technique to model microbial kinetic parameters and could thus become an additional tool in predictive mycology.

Production of red pigments by Monascus ruber in culture media containing corn steep liquor

The production of red pigments by Monascus ruber was evaluated utilizing complex culture media composed of glucose or sucrose (10 g/L), corn steep liquor (5 or 10 g/L) and monosodium glutamate (0, 5.0, 7.6, 11.4 or 15.2 g/L). Medium containing 10 g/L glucose, 5 g/L corn steep liquor and 7.6 g/L monosodium glutamate resulted the highest values of extracellular red pigment absorbance (20.7 U) and productivity (0.35 U/h). This medium also produced better results than using semi-synthetic medium with analytical grade reagents (12.4 U and 0.21 U/h). The cell growth was similar in both media (X <FONT FACE=Symbol>@</FONT> 6.5 g/L), indicating that the capacity of the cells to produce red pigments was higher in complex culture media. In addition, in the complex culture medium, less of the intracellular red pigments accumulated than in semi-synthetic medium (9.1% and 30%, respectively).

Mycoflora and Multimycotoxin Detection in Corn Silage: Experimental Study

Agricultural activities involve the use of crop preservation such as "trench-type" silo, which can sometimes be contaminated by fungi. To investigate the exposure of livestock and farm workers to fungal spores and mycotoxins, a multimycotoxin analysis method has been developed. Six mycotoxins (aflatoxin B1, citrinin, deoxynivalenol, gliotoxin, ochratoxin A, and zearalenone) were quantified by high-performance liquid chromatography coupled to mass spectrometry after solid-phase extraction. An experimental study of fungal species and mycotoxins was conducted in corn silage (Normandy, France) during 9 months of monitoring. The results indicated the recurrence of around 20 different species, with some of them being potentially toxigenic fungi such as Aspergillus fumigatus, Aspergillus parasiticus, Fusarium verticillioides, and Monascus ruber, and the detection of aflatoxin B1 (4-34 ppb), citrinin (4-25 ppb), zearalenone (23-41 ppb), and deoxynivalenol (100-213 ppb). This suggested a possible chronic exposure to low levels of mycotoxins.

Identification of new red pigments produced by Monascus ruber

A new monascus red pigment, which was produced in a defined medium with rice and hydrolytic bean powder was identified by IR, UV, NMR and ESI-MS. It was free pigments linked to lysine by amino group, where nitrogen replaced the pyronoid oxygen without hydrophilic side chain.

Taxonomic Investigation and Growth Characteristics of Citrinin Free Monascus Pilosus C1 Strain

ABSTRACTMonascus sp. C1 strain was isolated from cellulose as a natural pigment citrinin-free producing strain. Taxonomical investigation of the new strain was carried out on the recommended media and the results were compared with those of the referent strains—Monascus pilosus CBS 289.34, Monascus ruber CBS 291.34, Monascus purpureus CBS 285.34. The new strain was morphologically closer to the strain Monascus pilosus CBS 289.34. We did not observe any sexual structures of Monascus sp. C1 strain but there are not significant differences between both strains in their asexual reproduction. Monascus sp. C1strain is a prototrophic one, which utilizes quite well both ammonium and nitrate nitrogen sources. Assimilation and fermentation abilities of the experimental strain were studied too. It was found that both the tested and referent strains utilized quite well glucose and possess a high specific growth rate on media containing this sugar. The synthesis of citrinin was found only in the referent strain Monascus pilosus CBS 289.34. In anaerobic conditions both microorganisms can transform glucose to ethanol with high values of YEt/C—0.315 (for Monascus pilosus CBS 289.34) and 0.317 (for Monascus sp. C1) respectively. According to the morphological and physiological similarity between the referent strain Monascus pilosus CBS 289. 34 and the new one, Monascus sp.C1 is described as belonging to the species Monascus pilosus.

Red yeast rice extracts suppress adipogenesis by down-regulating adipogenic transcription factors and gene expression in 3T3-L1 cells

The effects of red yeast rice extracts (RE) on adipocyte differentiation of 3T3-L1 cells were studied. RE were extracted from embryonic rice fermented with red yeast ( Monascus ruber). These extracts significantly decreased glycerol-3-phosphate dehydrogenase (GPDH) activity and lipid accumulation, a marker of adipogenesis, in a dose-dependent manner. Moreover, mRNA expression levels of both CCAAT/enhancer-binding protein (C/EBP) α and peroxisome proliferator-activated receptor (PPAR) γ, the key adipogenic transcription factors, were markedly decreased by RE. RE also inhibited the expression of PPARγ at protein levels. RE decreased significantly gene expression of adipocyte fatty acid binding protein (aP2) and leptin, which are adipogenic marker proteins and C/EBPα and PPARγ target genes. These results suggest that the inhibitory effect of RE on adipocyte differentiation might be mediated through the down-regulated expression of adipogenic transcription factors and other specific genes.

Fungos filamentosos isolados de produtos derivados do milho comercializados em Recife, Pernambuco

Filamentous fungi isolated from corn derived products). The diversity of filamentous fungi was investigated in three corn derived products: corn meal, corn starch and pre-cooked corn flour. For isolation it was used the plating method, in surface and in depth, with Dichloran Rose Bengal Chloramphenicol Medium (DRBC). Twenty three species of fungi, belonging to eight genera were identified. The highest percentage of species was found in corn meal (47%) followed by corn starch (29.5%) and pre-cooked corn flour (23.5%). Aspergillus flavus Link, Fusarium moniliforme Sheldon, Penicillium funiculosum Thom and P. duclauxii Delacroix were found in all substrates; Penicillium brevicompactum Dierckx was present in corn meal and corn starch, while P. aurantiogriseum Dierckx and Rhizopus oryzae Went & Prinsen Geerlings were detected in corn meal and pre-cooked corn flour. Fusarium moniliforme formed the highest number of colonies forming units (352). Monascus ruber van Tieghen is being cited for the first time to Brazil, in processed corn. Species of Absidia, Aspergillus, Curvularia, Emericella, Fusarium, Monascus, Penicillium and Rhizopus have been mentioned as contaminant of corn derived products.

Modelling the combined effect of temperature, pH and aw on the growth rate of Monascus ruber, a heat-resistant fungus isolated from green table olives.

Growth modes predicting the effect of pH (3.5-5.0), NaCl (2-10%), i.e. aw (0.937-0.970) and temperature (20-40 degrees C) on the colony growth rate of Monascus ruber, a fungus isolated from thermally-processed olives of the Conservolea variety, were developed on a solid culture medium. Fungal growth was measured as colony diameter on a daily basis. The primary predictive model of Baranyi was used to fit the growth data and estimate the maximum specific growth rates. Combined secondary predictive models were developed and comparatively evaluated based on polynomial, Davey, gamma concept and Rosso equations. The data-set was fitted successfully in all models. However, models with biological interpretable parameters (gamma concept and Rosso equation) were highly rated compared with the polynomial equation and Davey model and gave realistic cardinal pHs, temperatures and aw. The combined effect of temperature, pH and aw on growth responses of M. ruber could be satisfactorily predicted under the current experimental conditions, and the models examined could serve as tools for this purpose. The results can be successfully employed by the industry to predict the extent of fungal growth on table olives.

Effect of rice--glycerol complex medium on the production of Lovastatin by Monascus ruber.

Response surface methodology (RSM) was employed to study the effect of the composition of the rice-glycerol complex medium on the production of lovastatin (Lvs) by the ascomycete Monascus ruber in mixed solid-liquid (or submerged) cultures at 25 degrees C. Four components (rice powder, peptone, glycerol, glucose) were studied to evaluate the approximate polynomial for all dependent variables, explaining their effects on the production of Lvs. The best composition derived from RSM regression was (in g/L) rice powder 34.4, peptone 10.8,, glucose 129, KNO3 8.0, MgSO4.7H2O 4.0 and glycerol 36.4 mL/L. With this composition, the Lvs production was 157 mg/L after 10 d of cultivation. In comparison with glycerol and glucose, the rice powder becomes a more suitable carbon source and represents a great potential for the production of Lvs.

Use of response surface methodology to optimize culture medium for production of lovastatin by Monascus ruber

Response surface methodology (RSM) was employed to study the effect of culture medium on the production of lovastatin in mixed solid-liquid state (or submerged) cultures by Monascus ruber. The maximal lovastatin yield (131 mg/L, average of three repeats) appeared at the region where the respective concentrations of rice powder, peptone, glycerin, and glucose were around 34.4 g/L, 10.8 g/L, 26.4 ml/L, and 129.2 g/L, respectively. The optimized medium resulted in a significant increase of lovastatin yield, as compared with that obtained by the fermentation of many other M. ruber species.

Heat resistance of Monascus ruber ascospores isolated from thermally processed green olives of the Conservolea variety

A heat-resistant fungus identified as Monascus ruber was isolated from thermally processed green olives of the Conservolea variety. Thermal death parameters of the ascospores were determined using Baranyi's primary predictive model in phosphate buffer (pH 7.0), citrate buffer (pH 4.0) and brine (pH 3.8) at two different NaCl levels (5.6% and 10.5%). The decimal reduction times ( D values) at 70, 75 and 80 °C in phosphate buffer (pH 7.0) were 37.31, 7.14 and 1.66 min, respectively, and the calculated z value was 7.4 °C. In citrate buffer (pH 4.0), the relative D values were 38.61, 7.83 and 2.10 min and the z value was 7.9 °C. In brine, the D 70 °C, D 75 °C and D 80 °C values increased from 46.08, 4.91 and 0.88 min to 72.99, 7.98 and 1.04 min, respectively, as the level of NaCl in brine increased from 5.6% to 10.5%, indicating a protective effect in ascospore inactivation. This effect was more pronounced at lower heating temperatures. It was concluded that a thermal process of F 80 °C=5 min could be considered as an effective thermal processing treatment. Results from this research could assist the table olive industry in designing an effective pasteurization plan to eliminate the fungus in thermally processed table olives.

Metabolites of Monascus ruber in silages

A total of 233 silages were examined and found that Monascus ruber was present in 43 samples with counts between 1 x 10(3) and 9 x 10(6) colony-forming units (CFU)/g (mean: 2 x 10(5) CFU/g). Monacolin K(L) and the hydroxy acid monacolin K(A) were detected by liquid chromatography-mass spectrometry in 45 and 50 of 233 samples at levels ranging from 25-15 600 and 28-65 400 microg/kg, respectively. Citrinin was found with high-performance liquid chromatography-fluorescence detection (FLD) in 14 (6%) samples, the concentrations varied between 2.4 and 64.2 microg/kg. The concentrations of citrinin were low and toxic effects are not anticipated. Monacolin K(A) and monacolin K(L) occur frequently and in considerable amounts in silages. These metabolites are believed to influence the metabolic activity of rumen anaerobic fungi resulting in a poorer digestion of crude fibre.

Kinetic analysis of red pigment and citrinin production by Monascus ruber as a function of organic acid accumulation.

In submerged cultures performed in synthetic medium containing glucose and glutamate, the filamentous fungus Monascus ruber produced a red pigment and a mycotoxin, citrinin. In oxygen-limiting conditions, the production of these two metabolites was growth-associated, as was the production of primary metabolites. In oxygen-excess conditions, the profile of citrinin production was typical of a secondary metabolite, since it was produced mostly during the stationary phase. In contrast, the production of the pigment decreased rapidly throughout the culture, showing a profile characteristic of an inhibitory mechanism. The organic acids produced during the culture, L-malate and succinate, were shown to be slightly inhibitory against pigment production, while citrinin production was unaffected. However, this inhibition could not account for the observed profile of pigment production in batch cultures. Other dicarboxylic acids such as fumarate or tartrate showed a similar effect to that provoked by malate and succinate as regards pigment production. It was concluded that the decrease in red pigment production during the culture was due to the inhibitory effect of an unknown product whose accumulation was favored in aerobic conditions.

Occupational asthma caused by a natural food colorant derived from Monascus ruber

Occupational asthma caused by a natural food colorant derived from Monascus ruber

Nitric oxide-mediated endothelium-dependent relaxation of rat thoracic aorta induced by aqueous extract of red rice fermented with Monascus ruber

Vasodilatory effects of aqueous extract of red rice fermented with Monascus ruber IFO32318 were examined on the isolated rat aorta. The water phase of fermented rice with Monascus (WP/FRM, 0.1–10 mg/ml) caused a transient relaxation of the endothelium-intact rat aorta precontracted with norepinephrine (NE, 300 nM). The WP/FRM-induced relaxation was abolished by removal of endothelium or in the presence of N G-nitro- l-arginine ( l-NNA, 10 μM), a nitric oxide (NO) synthase inhibitor. Neither atropine, a muscarinic receptor antagonist (10 μM), nor indomethacin, a cyclooxygenase inhibitor (10 μM), altered the WP/FRM-induced endothelium-dependent relaxation. γ-Aminobutyric acid (GABA), one of the principle components of the extract, did not affect the muscle tension of the aorta with intact endothelium. In addition, WP/FRM increased the production of NO in primary cultured endothelial cells from human umbilical vein. The enhanced production of NO by WP/FRM was diminished by pretreatment with l-NNA (10 μM). In conclusion, WP/FRM induces relaxation of rat aorta by releasing NO from endothelium. There seem to be some unknown factor(s) other than acetylcholine (Ach) and GABA, in the aqueous extract of red rice, which stimulate vascular endothelial cells to produce and/or release NO leading to endothelium-dependent relaxation by WP/FRM.

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

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

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

The growth and metabolic behaviour of the filamentous fungus Monascus ruber were studied in submerged cultures under various aeration and agitation conditions. Improving the oxygen supply, by increasing either the air input or the agitation speed, resulted in modified metabolism: the biomass yield, the consumption of the nitrogen source (monosodium glutamate), and the production of secondary metabolites (red pigment and citrinin) all increased. However, the citrinin production increased more than that of the red pigment. In consequence, a low oxygen transfer coefficient was required to improve the red pigment/citrinin production ratio. Copyright 1999 John Wiley & Sons, Inc.

Biosynthetic pathway of citrinin in the filamentous fungus monascus ruber as revealed by 13C nuclear magnetic resonance

Carbon isotope distribution of [13C]citrinin from Monascus ruber incubated with [13C]acetate revealed that the biosynthesis of the toxin originated from a tetraketide, instead of a pentaketide as has been shown for Penicillium and Aspergillus species. The production of polyketide red pigments and citrinin by M. ruber may therefore be regulated at the level of the tetraketide branch point.