Knowledge atlas Nature

Microbial pigments

Microbial pigments are extracted from bacteria which produce and store them in their growth process. Depending on the bacteria used, it is possible to produce a wide range of colours – yellow, red, green, violet, indigo. They are usually water insoluble and considered more as dyes than pigments. These pigments have antioxidant, antimicrobial, anti-inflammatory, antiproliferative, and immunosuppressive properties.

Name of Material in the local and Latin language: Bakterijski pigmenti
Type of Material: Organic
Commonly Found Locations: Laboratory environment
Major Industrial Producers or Suppliers: Colorifix (UK), PILI (France)

Colour: Range of colours depending on the microorganism: Streptomyces – gradients of violet, yellow, orange; Agrobacterium aurantiacum – pink; Pseudomonas aeruginosa – blue-green, indigo; Serratia marcescens – red; etc.
Density: Varying – depending on the compound
Hardness: Powder or oil form, produced by extraction after isolating and drying the bacteria. The dyeing process can also be conducted by using live bacterial cultures, usually in water surroundings.
Melting/Boiling Point: Varying – depending on the bacteria/microbial pigment used, the colouring process and material to be coloured.
Solubility: Water insoluble
Chemical Composition: Microbial pigments are in solid or oil form, originating from isolated and dried bacteria cultures that produce them during their growth. Pigments are either extracted from the cells or used as the crude extract, or else the entire colony is dried and later powdered and used for coloration.

Industrial and Crafts Applications: Microbial pigments still do not have a wide industrial application but offer possible solutions for textile and food industries, as well as pharmaceutical and cosmetic industries, as they are biocompatible. Dyeing techniques are most comparable to the traditional plant-based dyeing process for textile fibers.
Environmental Impact: Fermentative production of microbial pigments does not have any negative impact on the environment, and applying these pigments in the textile industry can resolve a large portion of the pollution from textile dyeing, while some fabrics can also be used as feedstock for the bacteria cultivation.
Innovative or Emerging Applications: Application of microbial pigments is still to be designed for wider uses, but it does align with the sustainable fashion principles. Additionally, some recent research conducted by the Group for Eco-Biotechnology and Drug Development, Institute of Molecular Genetics and Genetic Engineering in Belgrade, detected a possibility of bacteria using polyamide fibres as feedstock in the fermentative process. To this effect, the process can have the dual purpose of degrading polyamide fibres and producing pigment at the same time. The Group also successfully explores the possibility of live bacteria colouring.

Extraction Methods: Microbial pigments are extracted from bacteria cultures after the fermentative process. They can be extracted from the whole bacterium culture, bacterial cells, fermentation supernatant, or by drying and powdering the culture. Additionally, materials can be dyed during the fermentative process, by using the live culture.
Processing Techniques: Fermentation, extraction by green organic solvents (methanol, acetone…), column chromatography, and preparative thin-layer chromatography.
Sustainability and Environmental Considerations: The sustainability of pigment production is implied as pigment is a by-product of bacterial growth in the fermentative process. Additionally, with certain bacteria demonstrating the ability to degrade polyamide textiles, it can be considered as a sustainable approach to recycling textile waste.
Recycling and Waste Management: Microbial pigments disintegrate over time when exposed to the environmental conditions such as light or very high temperature. As they are a biomaterial, they are fully biodegradable.

Interesting Facts or Historical Anecdotes: The first appearance of prodigiosin was linked to the red colouration of polenta and wafers and was attributed to divine miracles, which is why the whole class of compounds bears this prodigious name.
Current Research and Developments: Microbial pigments are recognized as a highly potent means of reducing the polluting aspects of textile production. They are biocompatible and can have a wide range of application in various other industries as well. The potential for using waste material, especially food waste, in the fermentative process marks the microbial pigment production as sustainable and in line with the Green Deal, i.e., it can simultaneously contribute to procuring inventive methods for recycling different waste. BIOTON-bio-pigments obtained from waste for use in the paint and varnish industry project brings two innovations to the research of microbial pigments. On the one hand, it uses organic waste as the feedstock for the fermentative process, thus reducing the carbon footprint of pigment production. And on the other hand, together with the industry it develops a range of paints and coatings for JUB d.o.o Company, exploiting antibacterial antifungal properties. The project aims at reducing the emission of CO2, and simultaneously lowers the cost of waste removal in the production of paint.
Regulations or Restrictions: Due to the applicability of microbial pigments in food and cosmetic industries, their usage is highly regulated by quality protocols. Being ecotechnological products, their production should align with: EU Bioeconomy Strategy (2018), EU Plastics Strategy (2018), EU Green Deal (2019), Single-Use Plastics Directive (2019) incl. restrictions on oxo-degradable plastics, New EU Circular Economy Action Plan (2020), EU Climate Law (2021) & EU Taxonomy (2020), Sustainable Carbon Cycles (2021), Packaging & Packaging Waste Directive (revision 2022), EU Regulation on recycled plastic materials and articles intended to come into contact with foods (2022), Substantiating Claims on environmental performance (2022),Sustainable Products Initiative (2022) / Proposal for a new Ecodesign for Sustainable Products Regulation, Policy Framework for biobased, biodegradable and compostable plastics (2022), Waste Framework Directive (revision 2023).
Relevant Organizations, Associations, Producers: Textile industry, Biobased dyes & pigments, Arts, Industrial Biotechnology