Biotechnological approaches for the production of natural colorants by Talaromyces/Penicillium: A review

Development of dye-sensitized solar cells using pigment extracts produced by Talaromyces atroroseus GH2

The identification of more efficient, clean, secure, and competitive energy supply is necessary to align with the needs of sustainable devices. For this reason, a study for developing innovative dye-sensitized solar cells (DSSCs) based on microbial pigments is reported starting from Talaromyces atroroseus GH2. The fungus was cultivated by fermentation and the extracellular pigment extract was characterized by HPLC-DAD-ESI-MS analyses. The most abundant compound among the 22 azaphilone-type pigments identified was represented by PP-O. The device's behavior was investigated in relation to electrolyte and pH for verifying the stability on time and the photovoltaic performance. Devices obtained were characterized by UV-vis measurements to verify the absorbance intensity and transmittance percentage. Moreover, photovoltaic parameters through photo-electrochemical measurements (I-V curves) and impedance characteristics by Electrochemical Impedance Spectroscopy (EIS) were determined. The best microbial device showed a short-circuit current density (Jsc) of 0.69 mA/cm2, an open-circuit photo-voltage (Voc) of 0.27 V and a Fill Factor (FF) of 0.60. Furthermore, the power conversion efficiency (PCE) of the device was 0.11%. Thus, the present study demonstrated the potential of microbial origin pigments for developing DSSCs.

Euglena mutabilis exists in a FAB consortium with microbes that enhance cadmium tolerance

BACKGROUND

Synthetic algal-fungal and algal-bacterial cultures have been investigated as a means to enhance the technological applications of the algae. This inclusion of other microbes has enhanced growth and improved stress tolerance of the algal culture. The goal of the current study was to investigate natural microbial consortia to gain an understanding of the occurrence and benefits of these associations in nature. The photosynthetic protist Euglena mutabilis is often found in association with other microbes in acidic environments with high heavy metal (HM) concentrations. This may suggest that microbial interactions are essential for the protist's ability to tolerate these extreme environments. Our study assessed the Cd tolerance of a natural fungal-algal-bacterial (FAB) association whereby the algae is E. mutabilis.

RESULTS

This study provides the first assessment of antibiotic and antimycotic agents on an E. mutabilis culture. The results indicate that antibiotic and antimycotic applications significantly decreased the viability of E. mutabilis cells when they were also exposed to Cd. Similar antibiotic treatments of E. gracilis cultures had variable or non-significant impacts on Cd tolerance. E. gracilis also recovered better after pre-treatment with antibiotics and Cd than did E. mutabilis. The recoveries were assessed by heterotrophic growth without antibiotics or Cd. In contrast, both Euglena species displayed increased chlorophyll production upon Cd exposure. PacBio full-length amplicon sequencing and targeted Sanger sequencing identified the microbial species present in the E. mutabilis culture to be the fungus Talaromyces sp. and the bacterium Acidiphilium acidophilum.

CONCLUSION

This study uncovers a possible fungal, algal, and bacterial relationship, what we refer to as a FAB consortium. The members of this consortium interact to enhance the response to Cd exposure. This results in a E. mutabilis culture that has a higher tolerance to Cd than the axenic E. gracilis. The description of this interaction provides a basis for explore the benefits of natural interactions. This will provide knowledge and direction for use when creating or maintaining FAB interactions for biotechnological purposes, including bioremediation.

A New Species and Five New Records of Talaromyces (Eurotiales, Aspergillaceae) Belonging to Section Talaromyces in Korea

Talaromyces is a genus within the phylum Ascomycota (class Eurotiomycetes, order Eurotiales, family Trichocomaceae). Many species in this genus are known to produce diverse secondary metabolites with great potential for agricultural, medical, and pharmaceutical applications. During a survey on fungal diversity in the genus Talaromyces in Korea, six strains were isolated from soil, indoor air, and freshwater environments. Based on morphological, physiological, and multi-locus (ITS, BenA, CaM, and RPB2) phylogenetic analyses, we identified five previously unrecorded species in Korea (T. brevis, T. fusiformis, T. muroii, T. ruber, and T. soli) and a new species (T. echinulatus sp. nov.) belonging to section Talaromyces. Herein, detailed descriptions, illustrations, and phylogenetic tree are provided.

Two New Species of Talaromyces Sect. Trachyspermi Discovered in China

Two new species of sect. Trachyspermi isolated from soil are proposed, namely, T. albidus (ex-type AS3.26143T) and T. rubidus (ex-type AS3.26142T), based on the integrated taxonomic methods. Morphologically, T. albidus is characterized by slow growth, white gymnothecia, singly-borne asci and ellipsoidal echinulate ascospores. Talaromyces rubidus is distinguished by restricted growth, moderate to abundant red soluble pigment on CYA and YES, biverticillate penicilli, and  commonly ovoid to globose echinulate conidia. The two proposed novelties are further confirmed by the phylogenetic analyses of the concatenated BenA-CaM-Rpb2-ITS sequence matrix and the individual BenA, CaM, Rpb2 and ITS sequence matrices. Talaromyces albidus is closely related to T. assiutensis and T. trachyspermus, while T. rubidus is in the clade containing T. albobiverticillius, T. rubrifaciens, T. catalonicus, T. heiheensis, T. erythromellis, T. halophytorum, T. pernambucoensis, T. solicola and T. aerius.

Fascinating Furanosteroids and Their Pharmacological Profile

This review article delves into the realm of furanosteroids and related isoprenoid lipids derived from diverse terrestrial and marine sources, exploring their wide array of biological activities and potential pharmacological applications. Fungi, fungal endophytes, plants, and various marine organisms, including sponges, corals, molluscs, and other invertebrates, have proven to be abundant reservoirs of these compounds. The biological activities exhibited by furanosteroids and related lipids encompass anticancer, cytotoxic effects against various cancer cell lines, antiviral, and antifungal effects. Notably, the discovery of exceptional compounds such as nakiterpiosin, malabaricol, dysideasterols, and cortistatins has revealed their potent anti-tuberculosis, antibacterial, and anti-hepatitis C attributes. These compounds also exhibit activity in inhibiting protein kinase C, phospholipase A2, and eliciting cytotoxicity against cancer cells. This comprehensive study emphasizes the significance of furanosteroids and related lipids as valuable natural products with promising therapeutic potential. The remarkable biodiversity found in both terrestrial and marine ecosystems offers an extensive resource for unearthing novel biologically active compounds, paving the way for future drug development and advancements in biomedical research. This review presents a compilation of data obtained from various studies conducted by different authors who employed the PASS software 9.1 to evaluate the biological activity of natural furanosteroids and compounds closely related to them. The utilization of the PASS software in this context offers valuable advantages, such as screening large chemical libraries, identifying compounds for subsequent experimental investigations, and gaining insights into potential biological activities based on their structural features. Nevertheless, it is crucial to emphasize that experimental validation remains indispensable for confirming the predicted activities.

Red biocolorant from endophytic Talaromyces minnesotensis: production, properties, and potential applications

Fungal colorants are gradually entering the global color market, given their advantages of being less harmful to human health, as well as having greater stability and biotechnological potential, compared to other natural sources. The present work concerns the isolation and identification of an endophytic filamentous fungus, together with the chemical characterization and assessment of the fluorescence, toxicity, stability, and application potential of its synthesized red colorant. The endophytic fungus was isolated from Hymenaea courbaril, a tree from the Brazilian savannah, and was identified as Talaromyces minnesotensis by phenotypic and genotypic characterization. Submerged cultivation of the fungus resulted in the production of approximately 12 AU₅₀₀ of a red biocolorant which according to LC-DAD-MS analysis is characterized by being a complex mixture of molecules of the azaphilone class. Regarding cytotoxicity assays, activity against human hepatoblastoma (HepG2) cells was only observed at concentrations above 5.0 g L^-1, while antimicrobial effects against pathogenic bacteria and yeast occurred at concentrations above 50.0 g L^-1. The biocolorant showed high stability at neutral pH values and low temperatures (10 to 20 °C) and high half-life values (t_1/2), which indicates potential versatility for application in different matrices, as observed in tests using detergent, gelatin, enamel, paint, and fabrics. The results demonstrated that the biocolorant synthesized by Talaromyces minnesotensis has potential for future biotechnological applications. KEY POINTS: • An endophytic fungus, which was isolated and identified, synthesize a red colorant. • The colorant showed fluorescence property, low toxicity, and application potential. • The red biocolorant was highly stable at pH 8.0 and temperatures below 20°C.

A Zn(II)(2)Cys(6) transcription factor MPsGeI suppresses pigment biosynthesis in Monascus

High-quality natural edible pigments known as monascus pigments (MPs) are widely used in food, medicine, and chemical industries as active functional ingredients. At the transcriptional level, the expression of MPs genes are tightly controlled, limiting their productivity and color value. Hitherto our understanding of the regulation of expression of MPs genes has been rather limited. Here, we describe a pathway-specific Zn(II)(2)Cys(6) transcription factor involved in the MPs biosynthetic cluster named MPsGeI, which encodes a 813-amino-acid protein with six introns. Expression of all MPs biosynthetic genes and accumulation of MPs were remarkably increased in ΔMPsGeI strain, and MPs production was significantly reduced in MPsGeI over-expressing strain. Results clearly demonstrated that MPsGeI negatively regulates MPs accumulation via transcriptional regulation of MPs biosynthetic genes, and plays a central repressive role in MPs' biosynthesis. Transcriptomic analyses revealed that MPsGeI disruptant regulated higher concentrations of precursors flowing to pigment and resulted in accumulation of a large amount of red MPs in hyphae. This work offers an efficient method for increasing MPs's productivity and color value and provides novel insights into the regulatory mechanisms of fungal cellular processes, which will assist to enhance MPs production and application.

Production of Pigments under Submerged Culture through Repeated Batch Fermentation of Immobilized Talaromyces atroroseus GH2

Pigments of natural origin have become a research trend, and fungi provide a readily available alternative source. Moreover, developing novel processes that increase yields, reduce process time and simplify downstream processing is of increased interest. In this sense, this work proposes an alternative for Talaromyces atroroseus GH2 biomass re-utilization to produce pigments through consecutive batches using immobilized mycelium. Different support materials were evaluated for pigment production and immobilization capacity. Then, Taguchi’s method was applied to determine the effect of four factors related to fungal immobilization and pigment production (inoculum concentration, support density, working volume and support volume). Afterward, process kinetics for pigment production using immobilized cells of T. atroroseus GH2 in consecutive batches were evaluated. All evaluated factors were significant and affected pigment production and microorganism growth differently. At improved conditions, immobilization capacity reached 99.01 ± 0.37% and the pigment production was 30% higher than using free cells. Process kinetics showed that the production could continue for three batches and was limited by excessive microorganism growth. Indeed, more studies are still needed, but the immobilization of Talaromyces atroroseus GH2 represents a promising strategy for allowing downstream-processing intensification since immobilized biomass is easily removed from the fermentation media, thus paving the way for the further development of a continuous process.

Nitrogen Enriched Solid-State Cultivation for the Overproduction of Azaphilone Red Pigments by Penicillium sclerotiorum SNB-CN111

Azaphilones are microbial specialized metabolites employed as yellow, orange, red or purple pigments. In particular, yellow azaphilones react spontaneously with functionalized nitrogen groups, leading to red azaphilones. In this study, a new two-step solid-state cultivation process to produce specific red azaphilones pigments was implemented, and their chemical diversity was explored based on liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) and a molecular network. This two-step procedure first implies a cellophane membrane allowing accumulating yellow and orange azaphilones from a Penicillium sclerotiorum SNB-CN111 strain, and second involves the incorporation of the desired functionalized nitrogen by shifting the culture medium. The potential of this solid-state cultivation method was finally demonstrated by overproducing an azaphilone with a propargylamine side chain, representing 16% of the metabolic crude extract mass.

Assessment of artificial neural networks to predict red colorant production by Talaromyces amestolkiae

Consumer choice is typically influenced by color, leading to an increase in the use of artificial colorants by industry. However, several artificial colorants have been banned due to their harmful effects on human health and the environment, leading to increased interest in colorants from natural sources. Natural colorants can be found in plants, insects, and microorganisms. The importance of evaluating the technical and cost feasibility for the production of natural colorants are important factors for the replacement of artificial counterpart. Therefore, it is highly beneficial to predict the productivity of microbial colorants. The use of statistical methods that generate polynomial models through multiple regressions can provide information of interest about a bioprocess. However, modeling and control of biological processes require complex systems models, because they are nonlinear and non-deterministic systems. In this regard, artificial neural networks are suitable for estimating bioprocess variables with systems modeling. In this work, two different strategies were developed to predict the production of red colorants by Talaromyces amestolkiae, namely simulation by artificial neural networks (ANN) and response surface methodology (RSM). The results showed that the colorant concentration predicted by ANN is closer to the experimental data than that predicted by polynomial models fitted by multiple regression. Thus, this work suggests that the use of ANN can identify the initial conditions of the culture parameters that have the greatest influence on colorant production and can be a tool to be employed to improve the production of biotechnological products, such as microbial colorants.

Comparison of Pigment Production by Filamentous Fungal Strains under Submerged (SmF) and Surface Adhesion Fermentation (SAF)

Although synthetic colorants are widely used in many industries due to their high stability at different conditions in industrial processes, evidence of its negative impact on health and the environment is undeniable. Filamentous fungi are well known for their use as alternative sources to produce natural pigments. However, an adequate comparison of the productivity parameters between the fermentation systems could be limited to their heterogeneous conditions. Even though Solid-State Fermentations (SSF) on natural substrates are widely used for pigments production, complex media, and non-controlled variables (T, pH, medium composition), these systems could not only hamper the finding of accurate productivity parameters, but also mathematical modeling and genomics-based optimization. In this context, the present study screened five pigment-producing fungi by comparing Submerged (SmF) and Surface Adhesion Fermentation [biofilm (BF) and Solid-State (SSF)] with defined media and controlled variables. For this purpose, we used the same defined media with sucrose as the carbon source for pigment production on SmF, BF, and SSF, and BF and SSF were carried out on inert supports. Five molecularly identified Penicillium and Talaromyces strains isolated from the Peruvian rainforest were selected for their ability to produce yellowish-orange colorants. Highest productivities were obtained from T. brunneus LMB-HP43 in SmF (0.18 AU/L/h) and SSF (0.17 AU/L/h), and P. mallochii LMB-HP37 in SSF (0.18 AU/L/h). Both strains also exhibited the highest yields (AU/g biomass) in the three fermentation systems, reaching values greater than 18-folds in SSF compared to the other strains. Conversely, T. wortmannii LMB-HP14 and P. maximae LMB-HP33 showed no ability to produce pigments in the SSF system. The performed experiments accurately compared the effect of the fermentation system on yield and productivity. From this, further genomics approaches can be considered for an extensive analysis of pigment synthesis pathways and a genomics-driven optimization in the best fermentation system.

Chemical characterization and microencapsulation of extracellular fungal pigments

In this work, extracellular colored metabolites obtained from the filamentous fungi Talaromyces australis and Penicillium murcianum, isolated in the Andean-Patagonian native forests of Chile, were studied as prospect compounds to increase the sustainability of cosmetic products. The chemical and antioxidant properties of these natural pigments were characterized and strategies for their microencapsulation were also studied. UHPLC/MS-MS analyses indicated that the predominant metabolites detected in the cultures of P. murcianum were monascin (m/z = 411.15) and monashexenone (m/z = 319.10), while athrorosin H (m/z = 458.20) and damnacanthal (m/z = 281.05) were detected in cultures of T. australis. ORAC tests revealed that P. murcianum's metabolites had the greatest antioxidant properties with values higher than 2000 μmol of trolox equivalents/g. The fungal metabolites were successfully microencapsulated by ionic gelation into structures made of 1.3% sodium alginate, 0.2% chitosan, and 0.07% hyaluronic acid. The microencapsulation process generated structures of 543.57 ± 0.13 µm of mean diameter (d₅₀) with an efficiency of 30% for P. murcianum, and 329.59 ± 0.15 µm of mean diameter (d₅₀) and 40% efficiency, for T. australis. The chemical and biological characterization show the biotechnological potential of these fungal species to obtain pigments with antioxidant activity that could be useful in the cosmetic industry. The encapsulation process enables the production of easy-to-handle dry powder from the fungal metabolites, which could be potentially marketed as a functional cosmetic ingredient. KEY POINTS: • The predominant fungal pigments were of azaphilone and anthraquinoid classes. • The fungal pigments showed high antioxidant activity by ORAC assay. • Fungal pigment microcapsules obtained by ionic gelation were characterized.

Production of Natural Pigments by Penicillium brevicompactum Using Agro-Industrial Byproducts

The demand for natural pigments for industrial applications has significantly increased. Penicillium brevicompactum was recently reported as a promising pigments producer using submerged fermentation and a synthetic culture medium containing lactose. In this work, pigment production by P. brevicompactum was studied under different fermentation conditions, namely, submerged fermentation with free (SmF) and immobilized mycelium (SmFi), and solid-state fermentation (SSF). The potential of culture media composed of agro-industrial byproducts (cheese-whey (CW) and corn steep liquor (CSL)) was investigated for the first time as low-cost alternatives to pigment production by P. brevicompactum. The fungus showed great adaptability to the different culture media and types of fermentation, being able to synthesize pigments under all the tested conditions. A culture medium composed of 34.6 g/L of CW and 8 g/L of CSL proved to be the most suitable alternative to the synthetic medium, especially under SmF and SmFi. Our data also show that different mixtures of pigments (yellow, orange, and red) can be produced depending on the medium composition and the type of fermentation. Additionally, the immobilization and reuse of biomass to produce pigments by P. brevicompactum were demonstrated for the first time, suggesting the possibility of operating under repeated batch mode at an industrial scale.

Nature's palette: An emerging frontier for coloring dairy products

Consumers all across the world are looking for the most delectable and appealing foods, while also demanding products that are safer, more nutritious, and healthier. Substitution of synthetic colorants with natural colorants has piqued consumer and market interest in recent years. Due to increasing demand, extensive research has been conducted to find natural and safe food additives, such as natural pigments, that may have health benefits. Natural colorants are made up of a variety of pigments, many of which have significant biological potential. Because of the promising health advantages, natural colorants are gaining immense interest in the dairy industry. This review goes over the use of various natural colorants in dairy products which can provide desirable color as well as positive health impacts. The purpose of this review is to provide an in-depth look into the field of food (natural or synthetic) colorants applied in dairy products as well as their potential health benefits, safety, general trends, and future prospects  in food science and technology. In this paper, we listed a plethora of applications of natural colorants in various milk-based products.

Solid-state co-culture fermentation of simulated food waste with filamentous fungi for production of bio-pigments

The use of waste stream residues as feedstock for material production simultaneously helps reduce dependence on fossil-based resources and to shift toward a circular economy. This study explores the conversion of food waste into valuable chemicals, namely, bio-pigments. Here, a simulated food waste feedstock was converted into pigments via solid-state fermentation with the filamentous fungus Talaromyces albobiverticillius (NRRL 2120). Pigments including monascorubrin, rubropunctatin, and 7-(2-hydroxyethyl)-monascorubramine were identified as products of the fermentation via ultra-performance liquid chromatography coupled with quadrupole-time-of-flight electrospray ionization mass spectrometry. Pigments were obtained at concentrations of 32.5, 20.9, and 22.4 AU/gram dry substrate for pigments absorbing at 400, 475, and 500 nm, respectively. Pigment production was further enhanced by co-culturing T. albobiverticillius with Trichoderma reesei (NRRL 3652), and ultimately yielded 63.8, 35.6, and 43.6 AU/gds at the same respective wavelengths. This represents the highest reported production of pigments via solid-state fermentation of a non-supplemented waste stream feedstock. KEY POINTS: • Simulated food waste underwent solid-state fermentation via filamentous fungi. • Bio-pigments were obtained from fermentation of the simulated food waste. • Co-culturing multiple fungal species substantially improved pigment production.

A local Talaromyces atroroseus TRP-NRC isolate: isolation, genetic improvement, and biotechnological approach combined with LC/HRESI-MS characterization, skin safety, and wool fabric dyeing ability of the produced red pigment mixture

Background

During the last decade, enormous research efforts have been directed at identifying potent microorganisms as sustainable green cell factories for eco-friendly pigments. Talaromyces atroroseus has recently been shown to excrete large amounts of azaphilone mycotoxin-free red pigment mixture comprising some known coloring components together with many uncharacterized metabolites. In this study, a new Talaromyces atroroseus isolate was identified via sequencing of the fragment of the nuclear ribosomal gene cluster containing internal transcribed spacers and 5.8S rRNA gene. The parameters that affected the level of pigment production were optimized in uncommon static conditions of culture and genetic improvement, via γ-irradiation, to improve pigment yield. Moreover, chemical characterization using LC/MS and skin safety test of the target pigment mixture were precisely conducted to maximize its benefits as a natural and safe red pigment for wool fabrics.

Results

Molecular identification via the sequencing of the ITS of the rDNA encoding gene cluster revealed that the fungal isolate TRP-NRC was T. atroroseus TRP-NRC (deposited in GenBank under accession number MW282329). In the static conditions of culture, pigment production was dramatically enhanced to 27.36 g/L in an optimum yeast malt peptone medium of 2% mannitol at pH 2−4.5 and 30 °C for 7 days of incubation. Under exposure to a 400-Gy γ-radiation dose, pigment yield was increased to a 3-fold level higher than that recorded for the wild type. Based on the inter-simple sequence repeats (ISSR), as a molecular marker tool, the wild-type T. atroroseus TRP-NRC strain and its mutants were discriminated. The UHPLC/HRESI-MS analytical tool characterized 60 metabolites, including many unknown molecules, at appropriate concentrations. It is worthy to note that four mitorubrin derivatives were identified for the first time in T. atroroseus, i.e., mitorubrinolamine acetate, dihydro-PP-O, mitorobrinal, and mitorubrinol. The range of irritation indexes (0−0.1) demonstrated an adequate skin safety after the direct local application of the pigment mixture. Finally, the pigment mixture exhibited a remarkably good dyeing ability in wool fabrics, with high-fastness properties.

Conclusions

Because of its sustainable and economic production, the target red pigment mixture may be applied in the future in textile, food, cosmetics, or different pharmaceutical industries after extensive conventional safety and toxicity studies, which are currently under consideration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43141-022-00335-2.

Identification of azaphilone derivatives of Monascus colorants from Talaromyces amestolkiae and their halochromic properties

Currently, the ability to produce several kinds of water-soluble red natural colorants makes the genus Talaromyces particularly important to the dye industry, which can be an alternative to the use of harmful synthetic colorants. In this study, colored compounds produced by Talaromyces amestolkiae were extracted, characterized chemically and the color stability of the fermented broth without any extraction procedure was further evaluated over pH variation. Five azaphilones compounds were detected by Ultrahigh Performance Liquid Chromatography-Mass Spectrometry system, all being complexes of the fatty acid amino-hexanedioic acid and azaphilone Monascus colorants. The color of the fermented broth was stable at a wide range of pH (3-9). Furthermore, T. amestolkiae colorants precipitated through hydrolysis of key chemical groups at extremely acidic (pH 1) and lose red color in extremely basic (pH 13) medium, showing negative halochromism. Nevertheless, these findings enhance the industrial relevance of azaphilone colorants produced by biotechnological process.

Colorful Treasure From Agro-Industrial Wastes: A Sustainable Chassis for Microbial Pigment Production

Colors with their attractive appeal have been an integral part of human lives and the easy cascade of chemical catalysis enables fast, bulk production of these synthetic colorants with low costs. However, the resulting hazardous impacts on the environment and human health has stimulated an interest in natural pigments as a safe and ecologically clean alternative. Amidst sources of natural producers, the microbes with their diversity, ease of all-season production and peculiar bioactivities are attractive entities for industrial production of these marketable natural colorants. Further, in line with circular bioeconomy and environmentally clean technologies, the use of agro-industrial wastes as feedstocks for carrying out the microbial transformations paves way for sustainable and cost-effective production of these valuable secondary metabolites with simultaneous waste management. The present review aims to comprehensively cover the current green workflow of microbial colorant production by encompassing the potency of waste feedstocks and fermentation technologies. The commercially important pigments viz. astaxanthin, prodigiosin, canthaxanthin, lycopene, and β-carotene produced by native and engineered bacterial, fungal, or yeast strains have been elaborately discussed with their versatile applications in food, pharmaceuticals, textiles, cosmetics, etc. The limitations and their economic viability to meet the future market demands have been envisaged. The most recent advances in various molecular approaches to develop engineered microbiological systems for enhanced pigment production have been included to provide new perspectives to this burgeoning field of research.

Biotechnological advances for improving natural pigment production: a state-of-the-art review

In current years, natural pigments are facing a fast-growing global market due to the increase of people's awareness of health and the discovery of novel pharmacological effects of various natural pigments, e.g., carotenoids, flavonoids, and curcuminoids. However, the traditional production approaches are source-dependent and generally subject to the low contents of target pigment compounds. In order to scale-up industrial production, many efforts have been devoted to increasing pigment production from natural producers, via development of both in vitro plant cell/tissue culture systems, as well as optimization of microbial cultivation approaches. Moreover, synthetic biology has opened the door for heterologous biosynthesis of pigments via design and re-construction of novel biological modules as well as biological systems in bio-platforms. In this review, the innovative methods and strategies for optimization and engineering of both native and heterologous producers of natural pigments are comprehensively summarized. Current progress in the production of several representative high-value natural pigments is also presented; and the remaining challenges and future perspectives are discussed.

Fungal Pigment-Assisted Silver Nanoparticle Synthesis and Their Antimicrobial and Cytotoxic Potential

The biological production of nanoparticles has taken center stage among the various generation methods available owing to its environment-friendly characteristics and reduced energy requirements. A protocol for pigment-assisted silver nanoparticle (AgNP) synthesis was established, employing an extracellular composite pigment produced by the Ascomycota Talaromyces purpurogenus (presently Talaromyces purpureogenus). The extracellular pigment can reduce the precursor silver salt into nanoparticles in the presence of sodium hydroxide and light. Transmission electron microscopy may be used to characterize the bio-generated nanoparticles, which can also be tested for their biological properties using antimicrobial and anticancer assays.

Chemical Profiling, Bioactivity Evaluation and the Discovery of a Novel Biopigment Produced by Penicillium purpurogenum CBS 113139

Biobased pigments are environmentally friendly alternatives to synthetic variants with an increased market demand. Production of pigments via fermentation is a promising process, yet optimization of the production yield and rate is crucial. Herein, we evaluated the potential of Penicillium purpurogenum to produce biobased pigments. Optimum sugar concentration was 30 g/L and optimum C:N ratio was 36:1 resulting in the production of 4.1–4.5 AU (namely Pigment Complex A). Supplementation with ammonium nitrate resulted in the production of 4.1–4.9 AU (namely Pigment Complex B). Pigments showed excellent pH stability. The major biopigments in Pigment Complex A were N-threonyl-rubropunctamin or the acid form of PP-R (red pigment), N-GABA-PP-V (violet pigment), PP-O (orange pigment) and monascorubrin. In Pigment Complex B, a novel biopigment annotated as N-GLA-PP-V was identified. Its basic structure contains a polyketide azaphilone with the same carboxyl-monascorubramine base structure as PP-V (violet pigment) and γ-carboxyglutamic acid (GLA). The pigments were not cytotoxic up to 250 μg/mL.

Azaphilone alkaloids: prospective source of natural food pigments

Azaphilone, biosynthesized by polyketide synthase, is a class of fungal metabolites. In this review, after brief introduction of the natural azaphilone diversity, we in detail discussed azaphilic addition reaction involving conversion of natural azaphilone into the corresponding azaphilone alkaloid. Then, setting red Monascus pigments (a traditional food colorant in China) as example, we presented a new strategy, i.e., interfacing azaphilic addition reaction with living microbial metabolism in a one-pot process, to produce azaphilone alkaloid with a specified amine residue (red Monascus pigments) during submerged culture. Benefit from the red Monascus pigments with a specified amine residue, the influence of primary amine on characteristics of the food colorant was highlighted. Finally, the progress for screening of alternative azaphilone alkaloids (production from interfacing azaphilic addition reaction with submerged culture of Talaromyces sp. or Penicillium sp.) as natural food colorant was reviewed. KEY POINTS: • Azaphilic addition reaction of natural azaphilone is biocompatible • Red Monascus pigment is a classic example of azaphilone alkaloids • Azaphilone alkaloids are alterative natural food colorant.

Characterization of an Endophytic Strain Talaromyces assiutensis, CPEF04 With Evaluation of Production Medium for Extracellular Red Pigments Having Antimicrobial and Anticancer Properties

Considering the worldwide demand for colorants of natural origin, the utilization of ascomycete fungi as a prolific pigment producer unfolds a novel way to obtain these pigments for various applications, including food, cosmetic, and medical use. The presence of very few natural red pigment alternatives in the market also attracts research and industry priorities to unearth novel and sustainable red pigment producers. The present work is an attempt to identify a novel source of red color obtained from endophytic fungi isolated from terrestrial and marine habitats. Based upon the fungal capacity for pigment production, seven isolates of endophytic fungi were recognized as prospective pigment producers. Out of all, fungal isolate CPE04 was selected based upon its capacity to produce profuse extracellular red pigment. The isolate was identified as Talaromyces assiutensis, employing morphological features and phylogenetic characterization by internal transcribed spacer (ITS) sequences. To understand the chemical behavior of pigment molecules, an investigation of the chemical profile of fungal culture filtrate dried powder (CFDP) was performed using ultra-high-performance liquid chromatography-diode array detector-mass spectrometry (UPLC–DAD–MS). In total, eight compounds having pigment and pharmaceutical application were tentatively identified using UPLC–DAD–MS. Considering the commercial aspect of the stated work, an effort was also made for standardizing the upscaling of the pigment molecule. Investigations were performed for optimum medium and culturing conditions for maximum pigment production. CFDP was found to have a significant antibacterial activity against the bacterial pathogens Staphylococcus aureus (MTCC737), Vibrio cholerae (N16961), and methicillin-resistant S. aureus (MRSA) (ATCC BAA811). The CFDP showed a minimum inhibitory concentration at 64, 128, and 256 μg/ml against S. aureus, MRSA, and V. cholerae. A concentration-dependent (50–400 μg/ml) anticancer effect on HeLa cancer line was also observed, having a half-maximal inhibitory concentration (IC₅₀) at 300 μg/ml. The antioxidant potential of CFDP has also been proven with the help of an antioxidant assay against 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical (IC₅₀, 32.01 μg/ml); DNA nicking assay and reactive oxygen species were generated in HeLa cancer line cells. The CFDP was also found to have no cytotoxicity toward HEK 293 T cell line using alamar blue (resazurin), a cell metabolic activity reagent.

New Species of Talaromyces (Fungi) Isolated from Soil in Southwestern China

Southwestern China belongs among the global biodiversity hotspots and the Daba Mountains are recognized as one of the priority conservation areas. During the exploration of fungal biodiversity from soil samples collected from Mount Daba, two species of Talaromyces were discovered as new to science based on phylogenetic analyses and morphological comparisons. Talaromyces chongqingensis sp. nov. is a sister taxon of T. minioluteus and T. minnesotensis in the section Trachyspermi; and T. wushanicus sp. nov., affiliated to the section Talaromyces, is closely related to T. cnidii and T. siamensis. The new species differ from their sisters in DNA sequences, growth rates, and morphological characteristics. Descriptions and illustrations of them are provided in detail.

Recent Findings in Azaphilone Pigments

Filamentous fungi are known to biosynthesize an extraordinary range of azaphilones pigments with structural diversity and advantages over vegetal-derived colored natural products such agile and simple cultivation in the lab, acceptance of low-cost substrates, speed yield improvement, and ease of downstream processing. Modern genetic engineering allows industrial production, providing pigments with higher thermostability, water-solubility, and promising bioactivities combined with ecological functions. This review, covering the literature from 2020 onwards, focuses on the state-of-the-art of azaphilone dyes, the global market scenario, new compounds isolated in the period with respective biological activities, and biosynthetic pathways. Furthermore, we discussed the innovations of azaphilone cultivation and extraction techniques, as well as in yield improvement and scale-up. Potential applications in the food, cosmetic, pharmaceutical, and textile industries were also explored.

Toward improvements for enhancement the productivity and color value of Monascus pigments: a critical review with recent updates

Monascus pigments are a kind of high-quality natural edible pigments fermented by Monascus filamentous fungi, which have been widely used in food, cosmetics, medicine, textiles, dyes and chemical industries as active functional ingredients. Moreover, Monascus pigments have a good application prospect because of a variety of biological functions such as antibacterial, antioxidation, anti-inflammatory, regulating cholesterol, and anti-cancer. However, the low productivity and color value of pigments restrict their development and application. In this review, we introduced the categories, structures, biosynthesis and functions of Monascus pigments, and summarized the current methods for improving the productivity and color value of pigments, including screening and mutagenesis of strains, optimization of fermentation conditions, immobilized fermentation, mixed fermentation, additives, gene knockout and overexpression technologies, which will help to develop the foundation for the industrial production of Monascus pigments.

An Integrated Approach to Determine the Boundaries of the Azaphilone Pigment Biosynthetic Gene Cluster of Monascus ruber M7 Grown on Potato Dextrose Agar

Monascus-type azaphilone pigments (MonAzPs) are produced in multi-thousand ton quantities each year and used as food colorants and nutraceuticals in East Asia. Several groups, including ours, described MonAzPs biosynthesis as a highly complex pathway with many branch points, affording more than 110 MonAzP congeners in a small group of fungi in the Eurotiales order. MonAzPs biosynthetic gene clusters (BGCs) are also very complex and mosaic-like, with some genes involved in more than one pathway, while other genes playing no apparent role in MonAzPs production. Due to this complexity, MonAzPs BGCs have been delimited differently in various fungi. Since most of these predictions rely primarily on bioinformatic analyses, it is possible that genes immediately outside the currently predicted BGC borders are also involved, especially those whose function cannot be predicted from sequence similarities alone. Conversely, some peripheral genes presumed to be part of the BGC may in fact lay outside the boundaries. This study uses a combination of computational and transcriptional analyses to predict the extent of the MonAzPs BGC in Monascus ruber M7. Gene knockouts and analysis of MonAzPs production of the mutants are then used to validate the prediction, revealing that the BGC consists of 16 genes, extending from mrpigA to mrpigP. We further predict that two strains of Talaromyces marneffei, ATCC 18224 and PM1, encode an orthologous but non-syntenic MonAzPs BGC with 14 genes. This work highlights the need to use comprehensive, integrated approaches for the more precise determination of secondary metabolite BGC boundaries.

Carotenoids and Some Other Pigments from Fungi and Yeasts

Carotenoids are an essential group of compounds that may be obtained by microbiological synthesis. They are instrumental in various areas of industry, medicine, agriculture, and ecology. The increase of carotenoids' demand at the global market is now essential. At the moment, the production of natural carotenoids is more expensive than obtaining their synthetic forms, but several new approaches/directions on how to decrease this difference were developed during the last decades. This review briefly describes the information accumulated until now about the beneficial effects of carotenoids on human health protection, their possible application in the treatments of various diseases, and their use in the food and feed industry. This review also describes some issues that are linked with biotechnological production of fungal and yeasts carotenoids, as well as new approaches/directions to make their biotechnological production more efficient.

Alternative Extraction and Characterization of Nitrogen-Containing Azaphilone Red Pigments and Ergosterol Derivatives from the Marine-Derived Fungal Talaromyces sp. 30570 Strain with Industrial Relevance

Many species of Talaromyces of marine origin could be considered as non-toxigenic fungal cell factory. Some strains could produce water-soluble active biopigments in submerged cultures. These fungal pigments are of interest due to their applications in the design of new pharmaceutical products. In this study, the azaphilone red pigments and ergosterol derivatives produced by a wild type of Talaromyces sp. 30570 (CBS 206.89 B) marine-derived fungal strain with industrial relevance were described. The strain was isolated from the coral reef of the Réunion island. An alternative extraction of the fungal pigments using high pressure with eco-friendly solvents was studied. Twelve different red pigments were detected, including two pigmented ergosterol derivatives. Nine metabolites were identified using HPLC-PDA-ESI/MS as Monascus-like azaphilone pigments. In particular, derivatives of nitrogen-containing azaphilone red pigment, like PP-R, 6-[(Z)-2-Carboxyvinyl]-N-GABA-PP-V, N-threonine-monascorubramin, N-glutaryl-rubropunctamin, monascorubramin, and presumed N-threonyl-rubropunctamin (or acid form of the pigment PP-R) were the major pigmented compounds produced. Interestingly, the bioproduction of these red pigments occurred only when complex organic nitrogen sources were present in the culture medium. These findings are important for the field of the selective production of Monascus-like azaphilone red pigments for the industries.

Microbial Colorants Production in Stirred-Tank Bioreactor and Their Incorporation in an Alternative Food Packaging Biomaterial

Natural colorants from microbial fermentation have gained significant attention in the market to replace the synthetic ones. Talaromyces spp. produce yellow-orange-red colorants, appearing as a potential microorganism to be used for this purpose. In this work, the production of natural colorants by T. amestolkiae in a stirred-tank bioreactor is studied, followed by its application as additives in bio-based films. The effect of the pH-shift control strategy from 4.5 to 8.0 after 96 h of cultivation is evaluated at 500 rpm, resulting in an improvement of natural colorant production, with this increase being more significant for the orange and red ones, both close to 4-fold. Next, the fermented broth containing the colorants is applied to the preparation of cassava starch-based films in order to incorporate functional activity in biodegradable films for food packaging. The presence of fermented broth did not affect the water activity and total solids of biodegradable films as compared with the standard one. In the end, the films are used to pack butter samples (for 45 days) showing excellent results regarding antioxidant activity. It is demonstrated that the presence of natural colorants is obtained by a biotechnology process, which can provide protection against oxidative action, as well as be a functional food additive in food packing biomaterials.

Interfacing a phosphate catalytic reaction with a microbial metabolism for the production of azaphilone alkaloids

Exploring PO₄³⁻ as a Brønsted acid catalyst, a biocompatible amination reaction was successfully interfaced with the Penicillium sp. metabolism to produce sclerotiorin alkaloids.