The colors of life: an interdisciplinary artist-in-residence project to research fungal pigments as a gateway to empathy and understanding of microbial life

Background Biological pigmentation is one of the most intriguing traits of many fungi. It holds significance to scientists, as a sign of biochemical metabolism and organism-environment interaction, and to artists, as the source of natural colors that capture the beauty of the microbial world. Furthermore, the functional roles and aesthetic appeal of biological pigmentation may be a path to inspiring human empathy for microorganisms, which is key to understanding and preserving microbial biodiversity. A project focused on cross-species empathy was initiated and conducted as part of an artist-in-residence program in 2021. The aim of this residency is to bridge the current divide between science and art through interdisciplinary practice focused on fungi. Results The residency resulted in multiple products that are designed for artistic and scientific audiences with the central theme of biological pigmentation in fungi and other microorganisms. The first product is a video artwork that focuses on Aspergillus niger as a model organism that produces melanin pigment in a biosynthetic process similar to that of humans. The growth and morphology of this commonplace organism are displayed through video, photo, animation, and time-lapse footage, inviting the viewer to examine the likenesses and overlaps between humans and fungi. The second product is The Living Color Database, an online compendium of biological colors for scientists, artists, and designers. It links organisms across the tree of life, focusing on fungi, bacteria, and archaea, and the colors they express through biological pigmentation. Each pigment is represented in terms of its chemistry, its related biosynthesis, and its color expressions according to different indices: HEX, RGB, and Pantone. It is available at color.bio. Conclusions As fungal biotechnology continues to mature into new application areas, it is as important as ever that there is human empathy for these organisms to promote the preservation and appreciation of fungal biodiversity. The products presented here provide paths for artists, scientists, and designers to understand microorganisms through the lens of color, promoting interspecies empathy through research, teaching, and practice.

Safety Evaluation of Fungal Pigments for Food Applications

Pigments play a major role in many industries. Natural colors are usually much safer when compared to synthetic colors and may even possess some medicinal benefits. Synthetic colors are economical and can easily be produced compared to natural colors. In addition, raw plant materials for natural colors are limited and season dependent. Microorganisms provide an alternative source for natural colors and, among them, fungi provide a wide range of natural colorants that could easily be produced cheaply and with high yield. Along with pigment, some microbial strains are also capable of producing a number of mycotoxins. The commercial use of microbial pigments relies on the safety of colorants. This review provides a toxicity evaluation of pigments from fungal origins for food application.

Molecular Characterization of Fungal Pigments

The industrial application of pigments of biological origin has been gaining strength over time, which is mainly explained by the increased interest of the consumer for products with few synthetic additives. So, the search for biomolecules from natural origin has challenged food scientists and technologists to identify, develop efficient and less consuming strategies for extraction and characterization of biopigments. In this task, elucidation of molecular structure has become a fundamental requirement, since it is necessary to comply with compound regulatory submissions of industrial sectors such as food, pharmaceutical agrichemicals, and other new chemical entity registrations. Molecular elucidation consists of establishing the chemical structure of a molecule, which allows us to understand the interaction between the natural additive (colorant, flavor, antioxidant, etc) and its use (interaction with the rest of the mixture of compounds). Elucidation of molecular characteristics can be achieved through several techniques, the most common being infrared spectroscopy (IR), spectroscopy or ultraviolet-visible spectrophotometry (UV-VIS), nuclear-resonance spectroscopy (MAGNETIC MRI), and mass spectrometry. This review provides the details that aid for the molecular elucidation of pigments of fungal origin, for a viable and innocuous application of these biopigments by various industries.

Does the chemistry of fungal pigments demand the existence of photoactivated defense strategies in basidiomycetes?

The well-known photosensitizers hypericin, harmane, and emodin are typical pigments of certain mushroom species—is this a coincidence or an indication towards a photoactivated defense mechanism in the phylum Basidiomycota? This perspective article explores this hypothesis by cross-linking the chemistry of fungal pigments with structural requirements from known photosensitizers and insights from photoactivated strategies in the kingdom Plantae. Thereby, light is shed on a yet unexplored playground dealing with ecological questions, photopharmaceutical opportunities, and biotechnological potentials.

Preliminary Examination of the Toxicity of Spalting Fungal Pigments: A Comparison between Extraction Methods

Spalting fungal pigments have shown potential in technologies ranging from green energy generation to natural colorants. However, their unknown toxicity has been a barrier to industrial adoption. In order to gain an understanding of the safety of the pigments, zebrafish embryos were exposed to multiple forms of liquid media and solvent-extracted pigments with concentrations of purified pigment ranging from 0 to 50 mM from Chlorociboria aeruginosa, Chlorociboria aeruginascens, and Scytalidium cuboideum. Purified xylindein from Chlorociboria sp. did not show toxicity at any tested concentration, while the red pigment dramada from S. cuboideum was only associated with significant toxicity above 23.2 uM. However, liquid cultures and pigment extracted into dichloromethane (DCM) showed toxicity, suggesting the co-production of bioactive secondary metabolites. Future research on purification and the bioavailability of the red dramada pigment will be important to identify appropriate use; however, purified forms of the blue-green pigment xylindein are likely safe for use across industries. This opens the door to the adoption of green technologies based on these pigments, with potential to replace synthetic colorants and less stable natural pigments.

Aqueous Two-Phase System Extraction of Polyketide-Based Fungal Pigments Using Ammonium- or Imidazolium-Based Ionic Liquids for Detection Purpose: A Case Study

Demand for microbial colorants is now becoming a competitive research topic for food, cosmetics and pharmaceutics industries. In most applications, the pigments of interest such as polyketide-based red pigments from fungal submerged cultures are extracted by conventional liquid–liquid extraction methods requiring large volumes of various organic solvents and time. To address this question from a different angle, we proposed, here, to investigate the use of three different aqueous two-phase extraction systems using either ammonium- or imidazolium-based ionic liquids. We applied these to four fermentation broths of Talaromyces albobiverticillius (deep red pigment producer), Emericella purpurea (red pigment producer), Paecilomyces marquandii (yellow pigment producer) and Trichoderma harzianum (yellow-brown pigment producer) to investigate their selective extraction abilities towards the detection of polyketide-based pigments. Our findings led us to conclude that (i) these alternative extraction systems using ionic liquids as greener extractant means worked well for this extraction of colored molecules from the fermentation broths of the filamentous fungi investigated here; (ii) tetrabutylammonium bromide, [N4444]Br-, showed the best pigment extraction ability, with a higher putative affinity for azaphilone red pigments; (iii) the back extraction and recovery of the fungal pigments from ionic liquid phases remained the limiting point of the method under our selected conditions for potential industrial applications. Nevertheless, these alternative extraction procedures appeared to be promising ways for the detection of polyketide-based colorants in the submerged cultures of filamentous fungi.

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.