Dos interesantes contaminantes fúngicos filamentosos en muestras clínicas positivas a Trychophyton rubrum: una situación de curiosidad morfológica / Two interesting filamentous fungal contaminants in clinical samples positive to Trychophyton rubrum: a situation of morphological curiosity

Las dermatofitosis corresponden a un grupo de enfermedades micóticas comunes en piel y fanéreas, donde Trichophyton rubrum es el agente causante más frecuente a nivel mundial y presente en nuestros 2 casos de pacientes masculinos con estas micosis, una en uñas y la otra en piel. Sin embargo, el enfoque de esta publicación se basa principalmente en la presencia de 2 interesantes contaminantes (uno en cada caso clínico) presentes solo en los cultivos de las primeras siembras como saprófitos y por ende como propágulos de dispersión, asociados al ambiente y sin intervención clínica demostrada en ambas micosis. La descripción morfofisiológica de estos 2 contaminantes Metarhizium purpureo-genum(similis) y Monascus ruber fue más bien una curiosidad esencial que el micólogo clínico adquiere en su contínua formación y ante la posibilidad de infecciones mixtas, pudiendo conjugar sus hallazgos junto al análisis taxonómico y los factores geográficos y edáficos asociados a su distribución. (AU)

Dermatophytoses belongs to a group of common mycotic diseases in skin and pharynals, where Trichophyton rubrum is the most frequent causative agent worldwide and present in our 2 cases of male patients with these mycoses, one in nails and the other in skin. However, the focus of this publication is mainly about the presence of 2 interesting contaminants (one in each clinical case) present only in the crops of the first sowings as saprophytes and therefore as dispersal propagules, associated with the environment and without clinical intervention demonstrated in both mycoses. The morphophysiological description of these 2 contaminants, Metarhizium purpureogenum (similis) and Monascus ruber was rather an essential curiosity that the clinical mycologist acquires in his continuous training and in the face of the possibility of mixed infections, being able to combine his findings together with the taxonomic analysis and the geographic and edaphic factors associated with its distribution. (AU)

Evaluating the effects of microparticle addition on mycelial morphology, natural yellow pigments productivity, and key genes regulation in submerged fermentation of Monascus purpureus.

Morphology plays an important role in fungal fermentation and secondary metabolites biosynthesis. One novel technique, microparticle-enhanced cultivation was successfully utilized to control the morphology of Monascus purpureus precisely and enhance the yield of yellow pigments. The production of yellow pigments increased to 554.2 U/ml when 4 g/L 5000 mesh talc added at 24 h. Field emission scanning electron microscope observation indicated that the actual effect depends on the properties of microparticle. Sharp-edged microparticles showed better stimulatory effects than smooth, round-shaped ones. Particle size analysis, scanning electron microscope, and cell integrity evaluation proved obvious morphological changes were induced by talc addition, including smaller mycelial size, rougher hyphae, and decreased cell integrity. Furthermore, the expression levels of MrpigG, MrpigD, MrpigE, and MrpigH were significantly upregulated by the addition of talc. It indicated that the microparticle could not only affect the mycelial morphology, but also influence the expression levels of key genes in biosynthetic pathway of Monascus yellow pigments.

Mutational analysis of MpPhy reveals magnetoreception and photosensitivity involvement in secondary metabolites biosynthesis in Monascus purpureus.

Light or low frequency magnetic field (LF-MF) as one of the cultivation environments affects secondary metabolites (SMs) production of M. purpureus. Phytochrome (Phy) is a hybrid histidine kinase possessing dual properties of photoreceptor and kinase to sense red and far-red light. The interaction effects of LF-MF and light on SMs of M. purpureus was investigated by knocking out the Phy-like gene in M. purpureus (MpPhy) by homologous recombination. A MpPhy-deletion (ΔMpPhy) strain produced less Monascus pigments (MPs) and monacolin K (mon K) than the wild-type (WT) strain and reduced citrinin production by 78.3% on 10th day but didn't affect the biomass. These results indicated that the MpPhy gene is involved in SMs biosynthesis of M. purpureus. MPs production in WT was decreased significantly when the inoculum was exposed to white/blue/green/red light (500 Lux). But it in ΔMpPhy was no significant difference when exposed to white/red light. The colony size of ΔMpPhy was smaller on potato dextrose agar media containing 0.01% SDS. These results indicated that the deletion of MpPhy gene affected the aerial hyphae and increased sensitivity to cell membrane stress but decreased sensitivity to red light. The inoculum of both WT and ΔMpPhy was exposure to the LF-MF (50 Hz). The accumulation of WT secondary metabolites was not changed, while SMs production of ΔMpPhy was significantly enhanced under exposed to 2.0 mT LF-MF. This indicated that the decrease of SMs caused by the deletion of MpPhy gene was restored by LF-MF. It revealed that there is a crosstalk between magnetoreception and photosensitivity.

Promotion of monacolin K production in Monascus extractive fermentation: the variation in fungal morphology and in the expression levels of biosynthetic gene clusters.

BACKGROUND: Monacolin K, an important secondary metabolite of Monascus, possesses a cholesterol-lowering effect and is widely used in the manufacture of antihypertensive drugs. In the present study, we constructed an extractive fermentation system by adding non-ionic surfactant and acquired a high monacolin K yield. The mechanism was determined by examining both cell morphology and the transcription levels of the related mokA-I genes in the monacolin K biosynthetic gene cluster. RESULTS: The monacolin K yield was effectively increased to 539.59 mg L-1 during extraction, which was an increase of 386.16% compared to that in the control group fermentation. The non-ionic surfactant showed good biocompatibility with Monascus. Electron scanning microscopy revealed alterations in the morphology of Monascus. The loosened mycelial structure and increased number of cell surface wrinkles were found to be related to the increased cell-membrane permeability and extracellular accumulation of monacolin K. Gene expression levels were measured via a quantitative reverse transciptase-polymerase chain reaction. By contrast, in the control group, mokA, mokB, mokC, mokD and mokF showed higher-level and longer-term expression in the extractive fermentation group, whereas mokE and mokG did not present a similar trend. The expression levels of mokH and mokI, encoding a transcription factor and efflux pump, respectively, were also higher than the control levels. CONCLUSION: The addition of a non-ionic surfactant to Monascus fermentation effectively increases the yield of monacolin K by transforming the fungus morphology and promoting the expression of monacolin K biosynthesis genes. © 2021 Society of Chemical Industry.

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 UA510nm and molasses 5.08 UA510nm, and the mixture of rice flour and molasses showed the best result of 16.38 UA510nm. 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 UA510nm h-1 and maximum productivity rate of 0.17 UA510nm 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.

Volatile Organic Compound-Mediated Antifungal Activity of Pichia spp. and Its Effect on the Metabolic Profiles of Fermentation Communities.

Volatile organic compounds (VOCs) are chemicals responsible for antagonistic activity between microorganisms. The impact of VOCs on microbial community succession of fermentation is not well understood. In this study, Pichia spp. were evaluated for VOC production as a part of antifungal activity during baijiu fermentation. The results showed that the abundance of Pichia in the defect group (agglomerated fermented grains) was lower than that in control group, and a negative interaction between Pichia and Monascus was determined (P < 0.05). In addition, the disruption of fungi was significantly related to the differences of metabolic profiles in fermented grains. To determine production of VOCs from Pichia and its effect on Monascus purpureus, a double-dish system was assessed, and the incidence of M. purpureus reduction was 39.22% after 7 days. As to antifungal volatile compounds, 2-phenylethanol was identified to have an antifungal effect on M. purpureus through contact and noncontact. To further confirm the antifungal activity of 2-phenylethanol, scanning electron microscopy showed that 2-phenylethanol widely and significantly inhibited conidium germination and mycelial growth of filamentous fungi. Metatranscriptomic analysis revealed that the Ehrlich pathway is the metabolic path of 2-phenylethanol in Pichia and identified potential antifungal mechanisms, including protein synthesis and DNA damage. This study demonstrated the role of volatile compound-mediated microbial interaction in microbiome assembly and discovered a plausible scenario in which Pichia antagonized fungal blooms. The results may improve the niche establishment and growth of the functional yeast that enhances the flavor of baijiu.IMPORTANCE Fermentation of food occurs within communities of interacting species. The importance of microbial interactions in shaping microbial structure and metabolic performance to optimize the traditional fermentation process has long been emphasized, but the interaction mechanisms remain unclear. This study applied metabolome analysis and amplicon sequencing along with metatranscriptomic analysis to examine the volatile organic compound-mediated antifungal activity of Pichia and its effect on the metabolism of ethanol during baijiu fermentation, potentially enhancing the establishment of the fermentation niche and improving ethanol metabolism.

Enhancement of microbial pigment production from Monascus ruber by sodium octanoate addition.

BACKGROUND: The addition of fatty acids and other molecules to culture media may intensify the production of biomolecules, such as monascus pigments, however, few studies of this have been developed. Thus, the objective of the present study was to investigate the effects of adding sodium octanoate to the culture medium, with a view to increasing the synthesis and production of the pigments produced by Monascus ruber CCT 3802 on solid and submerged cultivations. METHODS: Monacus ruber CCT 3802 was cultivated on solid and submerged media supplemented with different concentrations of sodium octanoate. The radial growth rate of the colonies was obtained from the declivity of the linear regression of the radius of the colonies as a function of cultivation time and the kinetics of submerged cultivations were performed. The filtrate obtained was submitted to scanning spectrophotometry at a range from 350 to 550 nm and the color parameters were determined by using the CIELAB color system. The data were submitted to a univariate analysis of variance (ANOVA) and the means obtained for each treatment submitted to Tukey's test using Statistica version 5.0 software at a 5% level of significance. RESULTS: Sodium octanoate exerted a strong influence on growth and pigment production in solid and submerged cultivations. The values for L*, a* and b* were positive for pigments produced, with regards to colors close to red and yellow. In the media supplemented with 1.0 mM and 1.5 mM of sodium octanoate, the production of red pigments became expressive from 48 hours-cultivation, increasing considerably from the second to the fourth days. This shows that supplementation with sodium octanoate provides a greater production of pigments in a shorter time interval than the control culture, which required 144 hours of cultivation to present a higher value for AU510nm, which directly influenced pigment productivity. CONCLUSIONS: The addition of sodium octanoate exerted a significant influence on both microbial growth and pigment production in both solid and submerged cultivations. The supplementation of the submerged cultures with sodium octanoate was responsible for an expressive production of pigments in just 48 hours, whereas 144 hours were necessary in the absence of sodium octanoate. These results are promising for increasing the productivity of pigment production, including possibilities for application on an industrial scale.

Effects on the sporulation and secondary metabolism yields of Monascus purpureus with mokH gene deletion and overexpression.

Monacolin K is a secondary metabolite of Monascus and is known to decrease cholesterol levels in humans. There are 9 genes (mokA-mokI) controlling its biosynthesis, of which mokH is thought to act as a pathway-specific regulator. In this study, the Monascus purpureus M1 strain was compared with mokH gene deletion strains (△H1) and overexpression strains (H7). The monacolin K yields in the △H1 strain were reduced by 52.05 %, and increased in the H7 strain by 82 %. The mycelium samples of the M1, △H1, and H7 strains were found to vary with scanning electron microscopy. Compared to the M1 strain, some mycelium of the △H1 strain showed obvious folding and expansion, while the mycelium of the H7 strain was fuller. Besides, these results indicate that the mokH gene can increase the yield of monacolin K by regulating the expression level of mokA-mokI genes, and influence the production of Monascus pigment. The study is the first to combine deletion and overexpression techniques to further verify the mokH gene and get the desired results in M. purpureus.

Effect of nonionic surfactant Brij 35 on morphology, cloud point, and pigment stability in Monascus extractive fermentation.

BACKGROUND: Nonionic surfactant Brij 35 in submerged fermentation of Monascus can significantly increase Monascus pigment yield. Here, the effects of nonionic surfactant Brij 35 on Monascus pigment secretion in extractive fermentation are discussed in terms of cell morphology, cloud point change, and pigment stability. RESULTS: At Brij 35 concentrations up to 32 g L-1 , the higher concentrations led to the loosening of the network structure on the surface of the fungal wall, enhanced cell wall permeability, and increased abundance of lipid droplets. Alternatively, when the concentration of Brij 35 exceeded 32 g L-1 , a large amount of substances accumulated on the surface of the fungal wall, permeability reduced, and the degree of oil droplet dispersion in cells decreased. Further, during extractive fermentation, Brij 35 induced formation of a grid structure on the fungal wall surface beginning on day 2, increased the number of intracellular lipid droplets, and promoted intracellular pigment secretion into the extracellular environment. When the cloud point temperature in the fermentation system approached that of fermentation, the nonionic surfactant exhibited stronger Monascus pigment extraction capacity, thereby enhancing pigment yield. Hence, Brij 35 can improve pigment stability and effectively reduce damage caused by natural factors, such as light and temperature. CONCLUSION: Brij 35 promotes the secretion of pigment by changing the fungal wall structure and cloud point, as well as by improving pigment stability. © 2020 Society of Chemical Industry.

Evaluation of tyrosol and farnesol as inducer in pigment production by Monascus purpureus ATCC16365.

This study focused on investigating the effect of exogenously applied two quorum sensing molecules (tyrosol and farnesol) on the synthesis of bioactive metabolites (pigments, lactic acid, ethanol, and citric acid) in Monascus purpureus ATCC16365. None of the tested concentrations (62.5, 125, 250, and 500 µl/L) of farnesol affected the synthesis of metabolites as well as cell growth. As with farnesol application, none of the tested concentrations (3.45, 6.9, 13.8, and 27.6 mg/L) of tyrosol caused a significant change in the synthesis of lactic acid and citric acid as well as cell growth. Conversely, all of the tested concentrations of tyrosol increased pigment synthesis but reduced ethanol synthesis, compared with the control. Maximum increases (3.16-, 2.68-, and 2.87-fold increase, respectively) in yellow, orange, and red pigment production were achieved, especially when 6.9-mg/L tyrosol was added to the culture on day 3. On the contrary, 6.9-mg/L tyrosol reduced the content of citrinin by approximately 51.5%. This is the first report on the effect of tyrosol and farnesol on the synthesis of Monascus metabolites. Due to potential properties, such as low price, nonhuman toxicity, promotion of pigment synthesis, and reduction in citrinin synthesis, tyrosol can be used as a novel inducer in the fermentative production of Monascus pigments.

Overexpression of global regulator LaeA increases secondary metabolite production in Monascus purpureus.

Monascus is a filamentous fungus that produces several secondary metabolites. Here, we investigated the effects of the global regulator LaeA on the synthesis of pigments and monacolin K in Monascus purpureus with spectrophotometer and HPLC methods. The LaeA gene was isolated from M. purpureus M1 to create an overexpression construct. An LaeA-overexpressing strain L3 was with 48.6% higher monacolin K production than the M1 strain. The L3 strain also produced higher Monascus pigments than the M1 strain. SEM showed that LaeA overexpression resulted in altered mycelial morphology. Compared with the M1 strain, the L3 strain expressed higher levels of monacolin K synthesis-related genes mokA, mokB, mokE, and mokH. Overall, these results suggest that LaeA plays a role in regulating the production of secondary metabolites and mycelial growth in Monascus. This study provides important insights into the mechanisms underlying the effects of the LaeA gene on the secondary metabolites of M. purpureus.

The Effect of Blue Light on the Production of Citrinin in Monascus purpureus M9 by Regulating the mraox Gene through lncRNA AOANCR.

Blue light, as an important environmental factor, can regulate the production of various secondary metabolites of Monascus purpureus M9, including mycotoxin-citrinin, pigments, and monacolin K. The analysis of citrinin in Monascus M9 exposed to blue light for 0 min./d, 15 min./d, and 60 min./d showed that 15 min./d of blue light illumination could significantly increase citrinin production, while 60 min./d of blue light illumination decreased citrinin production. Analysis of long non-coding RNA (LncRNA) was performed on the transcripts of Monascus M9 under three culture conditions, and this analysis identified an lncRNA named AOANCR that can negatively regulate the mraox gene. Fermentation studies suggested that alternate respiratory pathways could be among the pathways that are involved in the regulation of the synthesis of citrinin by environmental factors. Aminophylline and citric acid were added to the culture medium to simulate the process of generating cyclic adenosine monophosphate (cAMP) in cells under illumination conditions. The results of the fermentation showed that aminophylline and citric acid could increase the expression of the mraox gene, decrease the expression of lncRNA AOANCR, and reduce the yield of citrinin. This result also indicates a reverse regulation relationship between lncRNA AOANCR and the mraox gene. A blue light signal might regulate the mraox gene at least partially through lncRNA AOANCR, thereby regulating citrinin production. Citrinin has severe nephrotoxicity in mammals, and it is important to control the residual amout of citrinin in red yeast products during fermentation. LncRNA AOANCR and mraox can potentially be used as new targets for the control of citrinin production.

Acidic conditions induce the accumulation of orange Monascus pigments during liquid-state fermentation of Monascus ruber M7.

The influence of pH on the biosynthesis of orange Monascus pigments (OMPs) in Monascus ruber M7 was investigated. Under acidic fermentation conditions, pigment mixtures predominantly rich in OMPs were obtained. HPLC analysis revealed the presence of four orange components (O1-O4) and four yellow components (Y1-Y4) in the mixtures, and the dominant ones were O1 and O3, which accounted for 56.0% to 75.9% of the total pigments in the pH range 3-6. Subsequently, O1 and O3 were identified by LC-DAD-ESI/MS as Rubropunctatin and Monascorubrin, respectively. The yield of OMPs was observed to be inversely dependent on pH. At pH 3, large amounts of OMPs with high purity (79.1%) were accumulated. A real-time quantitative PCR analysis revealed that the expression of genes related to the biosynthesis of OMPs in M. ruber M7 was upregulated at acidic pH as compared to neutral pH, and the variation in the level of expression of these genes with pH was consistent with the production of OMPs. These results indicated that the large accumulation of OMPs under acidic condition involved the acidic pH-induced transcription of genes related to the biosynthesis of OMPs. These results would contribute towards the development of an efficient technology for large-scale production of OMPs.

Effects of rutin and its derivatives on citrinin production by Monascus aurantiacus Li AS3.4384 in liquid fermentation using different types of media.

The mycotoxin citrinin is often produced during fermentation of Monascus products. We studied the effects of flavonoids on citrinin production by Monascus aurantiacus Li AS3.4384 (MALA) by adding rutin, α-glucosylrutin, or troxerutin to the fermentation medium, in a first-of-its-kind study. Appropriate amounts of rutin, α-glucosylrutin, or troxerutin did not affect normal mycelial growth. Addition of 5.0 g/l of rutin only weakly reduced (29.2%) citrinin production, relative to inhibition by 5 g/l α-glucosylrutin or troxerutin (by 54.7% and 40.6%, respectively). In starch inorganic liquid culture media, addition of 20.0 g/l of troxerutin, followed by fermentation for 12 days, reduced citrinin yield by 75.26%. Addition of 15.0 g/l of troxerutin to low-starch peptone liquid fermentation media reduced citrinin yield by 87.9% after 14 days of fermentation, and addition of 30.0 g/l troxerutin to yeast extract sucrose liquid media for 12 days reduced citrinin yield by 53.7%.

NaCl Inhibits Citrinin and Stimulates Monascus Pigments and Monacolin K Production.

Applications of beneficial secondary metabolites produced by Monascus purpureus (M. purpureus) could be greatly limited for citrinin, a kidney toxin. The link of NaCl with cell growth and secondary metabolites in M. purpureus was analyzed with supplementations of different concentrations of NaCl in medium. The content of citrinin was reduced by 48.0% but the yellow, orange, red pigments and monacolin K productions were enhanced by 1.7, 1.4, 1.4 and 1.4 times, respectively, compared with those in the control using NaCl at 0.02 M at the 10th day of cultivation. NaCl didn't affect the cell growth of M. purpureus. This was verified through the transcriptional up-regulation of citrinin synthesis genes (pksCT and ctnA) and the down-regulation of the Monascus pigments (MPs) synthesis genes (pksPT and pigR). Moreover, the reactive oxygen species (ROS) levels were promoted by NaCl at the 2nd day of cultivation, and then inhibited remarkably with the extension of fermentation time. Meanwhile, the activities of superoxide dismutase (SOD) and catalase (CAT), and the contents of total glutathione (T-GSH) were significantly enhanced in the middle and late stages of cultivation. The inhibition effect on colony size and the growth of aerial mycelia was more obvious with an increased NaCl concentration. Acid and alkaline phosphatase (ACP and AKP) activities dramatically increased in NaCl treatments. NaCl could participate in secondary metabolites synthesis and cell growth in M. purpureus.

iTRAQ-Based Quantitative Proteomic Analysis Reveals Changes in Metabolite Biosynthesis in Monascus purpureus in Response to a Low-Frequency Magnetic Field.

BACKGROUND: Low-frequency magnetic fields (LF-MFs) dampen the citrinin output by Monascus purpureus in fermentations. The influence of LF-MFs on biosynthesis by M. purpureus was evaluated at the protein level. METHODS: Cultures were treated with a 1.6-mT MF from day 0 to day 2 of incubation, and secondary metabolite production was evaluated on the day 12 of incubation. All proteins were extracted from M. purpureus mycelia and subjected to isobaric tags for relative and absolute quantification (iTRAQ) labeling and subsequent liquid chromatography/mass spectrometry (LC-MS/MS) analysis on day 6 of fermentation. RESULTS: There was no difference in biomass between the treated samples and the control. Citrinin production was 46.7% lower, and the yields of monacolin K and yellow, orange, and red pigment were 29.3%, 31.3%, 41.7%, and 40.3% higher, respectively, in the exposed samples compared to the control. Protein expression in M. purpureus under LF-MF treatment was quantified using iTRAQ technology. Of 2031 detected proteins, 205 were differentially expressed. The differentially-expressed proteins were subjected to Gene Ontology (GO) functional annotation and statistical analysis, which revealed that they mainly refer to biological metabolism, translation, antioxidant, transport and defense pathways. Among all the tagged proteins, emphasis was placed on the analysis of those involved in the synthesis of citrinin, pigment and monacolin K was emphasized. CONCLUSIONS: LF-MFs affected Monascus secondary metabolism at the protein level, and aggregate data for all the protein profiles in LF-MF-treated Monascus was obtained.

MptriA, an Acetyltransferase Gene Involved in Pigment Biosynthesis in M. purpureus YY-1.

Monascus pigments (Mps) have been used as food colorants for several centuries in Asian countries. MptriA is a putative acetyltransferase gene involved in the MPs biosynthesis. To analyze the function of MptriA, an MptriA disruption strain (Δ MptriA) and a complementation strain (Δ MptriA:: MptriA) were successfully obtained In addition to the loss of color, the disruption of MptriA had little effect on the phenotypes during growth on four different media. The Δ MptriA strain showed decreased pigment and citrinin production during the liquid-fermentation process. Transcriptional analysis showed that the expression of several genes involved in the synthesis of pigments and citrinin was down-regulated in Δ MptriA. These results demonstrated that the role of MptriA was to transfer an acyl group to the pyranoquinone structure of the polyketide chromophore during Monascus pigment biosynthesis and to influence the citrinin biosynthesis pathway. This study contributes to the exploration of pigment biosynthesis in M. purpureus.

Effects of hurdle technology on Monascus ruber growth in green table olives: a response surface methodology approach

ABSTRACT An ascomycetes fungus was isolated from brine storage of green olives of the Arauco cultivar imported from Argentina and identified as Monascus ruber. The combined effects of different concentrations of sodium chloride (3.5-5.5%), sodium benzoate (0-0.1%), potassium sorbate (0-0.05%) and temperature (30-40 °C) were investigated on the growth of M. ruber in the brine of stored table olives using a response surface methodology. A full 24 factorial design with three central points was first used in order to screen for the important factors (significant and marginally significant factors) and then a Face-Centered Central Composite Design was applied. Both preservatives prevented fungal spoilage, but potassium sorbate was the most efficient to control the fungi growth. The combined use of these preservatives did not show a synergistic effect. The results showed that the use of these salts may not be sufficient to prevent fungal spoilage and the greatest fungal growth was recorded at 30 °C.

Chicken feather peptone: A new alternative nitrogen source for pigment production by Monascus purpureus.

Peptones are accepted as one of the most favourable nitrogen sources supporting pigment synthesis in Monascus purpureus. The present study was performed to test the feasibility of chicken feather peptone (CFP) as nitrogen source for pigment production from M. purpureus ATCC16365. CFP was compared with fish peptone (FP) and protease peptone (PP) in order to elucidate its effectiveness on pigment production. CFP was prepared from waste feathers using hydrolysis (KOH) and neutralization (H2SO4) methods. The protein content of CFP was determined as 67.2 g/100 g. Optimal concentrations of CFP and glucose for pigment production were determined as 3 and 20 g/L, respectively. A medium pH of 5.5 and an incubation period of 7-days were found to be more favourable for pigment production. In CFP, PP and FP media, yellow pigment absorbances were 2.819, 2.870 and 2.831, red pigment absorbances were 2.709, 2.304 and 2.748, and orange pigment absorbances were 2.643, 2.132 and 2.743, respectively. Sugar consumption and mycelia growth showed the similar trends in CFP, FP and PP media. This study indicates that the peptone from chicken feathers may be a good nutritional substrate for pigment production from M. purpureus.

Effects of hurdle technology on Monascus ruber growth in green table olives: a response surface methodology approach.

An ascomycetes fungus was isolated from brine storage of green olives of the Arauco cultivar imported from Argentina and identified as Monascus ruber. The combined effects of different concentrations of sodium chloride (3.5-5.5%), sodium benzoate (0-0.1%), potassium sorbate (0-0.05%) and temperature (30-40°C) were investigated on the growth of M. ruber in the brine of stored table olives using a response surface methodology. A full 24 factorial design with three central points was first used in order to screen for the important factors (significant and marginally significant factors) and then a Face-Centered Central Composite Design was applied. Both preservatives prevented fungal spoilage, but potassium sorbate was the most efficient to control the fungi growth. The combined use of these preservatives did not show a synergistic effect. The results showed that the use of these salts may not be sufficient to prevent fungal spoilage and the greatest fungal growth was recorded at 30°C.