Fermentation for Pigments
Pigments are defined as finely divided and usually water-insoluble colorants that display different colors by absorbing and reflecting the visible light. Compared to dyes, pigments are of larger molecular weight, poorer water solubility and lower transparency. Organic pigments synthesized through chemical reactions can cause many serious health hazards such as toxicity, carcinogenicity and teratogenicity. With increasing public health awareness, replacing synthetic pigments with safer and more environmentally friendly natural pigments has become a current marketing trend. In addition to their use as colorants, many natural pigments are showing great potential in the pharmaceutical, nutrition and skincare industries due to their health benefits. Pigments obtained by fermentation of bacteria, fungi, yeasts, cyanobacteria and microalgae are increasingly in demand in the food, leather and textile industries due to their natural origin and effective bioactive properties. Various agro-industrial residues such as rice bran, wheat bran and cassava have been employed for pigment production because of their low cost, natural origin, waste utilization and high pigment stimulating properties.
Fig 1. Production of bio-based pigments from food processing industry by-products. (Arikan, E. B.; et al. 2020)
Advantages of Pigments Production by Fermentation
- Does not pose a health risk to humans
- Less polluting and more environmentally friendly than traditional petrochemical pigments
- Less energy consumption because their production process does not use petrol and chemicals
- High scale production with low cost and accurate production
Fermentation Techniques Applied in Pigments Production
Due to the high cost of current pigment production technologies used on an industrial scale, there is a need to develop low-cost pigment production processes. In the SSF process, the solid substrate not only provides the nutrients to the microbial culture growing in it, but also acts as an anchorage for the cells. For example, jackfruit seed powder can be used as a substrate for the production of pigments by Aspergillus oryzae in SSF, and the process of pigment preparation is simple and inexpensive. It is demonstrated that the color of the pigment was stable over a wide pH range, apparently due to the buffering nature of the substrate, which may be important for its use in food applications.
A variety of natural substrates are applied as carbon and nitrogen sources in submerged fermentations to enhance the pigment production by bacteria, fungi, yeast, cyanobacteria, and microalgae. In general, these microorganisms are highly sensitive to physicochemical parameters. Therefore, these microorganisms require various in vitro culture conditions to produce more pigments in submerged fermentation.
Fig 2. Natural Red Pigment Production in Submerged Fermentation Systems. (Silbir, S.; Goksungur, O. 2010)
Classic Fermentation Process in Pigments Production
Microbial Cultivation
Typical pigment-producing microorganisms include Phaffia rhodozyma (yeast that produces carotenoids), Monascus (fungus that produces monascus red pigments), Blakeslea trispora (fungus that produces orange pigments such as β-carotene), Streptomyces cyaneus (fungus that produces black pigment-melanin) and Serratia (bacteria that produce red pigment - prodigiosin)
Optimization of Key Influencing Factors
Pigment accumulation is generally related to cell growth and is influenced by nutritional factors (carbon source, nitrogen source, C/N ratio), microbiological parameters and environmental conditions.
In terms of environmental conditions, several important aspects should be evaluated and optimized for the solid-state fermentation (SSF) include the moisture content of the fermentation process, physical and structural properties of the substrate, temperature, pH and agitation.
Another cultivation process is submerged fermentation (SmF), which is developed based on the liquid culture for most microorganisms and is strongly influenced by factors such as temperature, pH, and agitation. For photosynthetic microorganisms, light source, light intensity and photoperiod have been shown to be key factors affecting pigment production.
A comprehensive optimization of the fermentation process is also required to obtain a high yield production of the desired pigments. Response surface methodology (RSM) can address multivariate data from appropriately designed experiments and help improve pigment production by optimizing the culture media, process parameters and extraction conditions.
Development of Novel Immobilization Methods
Immobilization techniques provide a viable method to improve cell stability and reusability for downstream cell isolation and continuous manipulation. Immobilization of bacteria and yeast has been applied for carotenoid production. For Mycobacteria, SSF is considered to be superior to submerged fermentation (SmF) for pigment production. Numerous studies have shown that immobilization cultivation using cell entrapment and adsorption methods can mimic the solid-state environment of SSF and effectively increase pigment production by Mycobacteria. Scientists have developed a novel integrated fermentation system consisting of a surfactant and an in situ extractant for the efficient production of yellow pigment by Monascus purpureus. Key factors such as alleviating the product inhibition, increasing the membrane permeability, altering the hyphal morphology and affecting the cellular activity are considered to be the underlying mechanisms.
Our Services for Fermentation Production of Pigments
- Fermentation CDMO Service
- Strain Development Service
- Fermentation Process Optimization
- Fermentation for Special Small Molecules
- GRAS Services
BOC Sciences provides fermentation CDMO service for microbial pigments. We work on fermentation-related projects for the microbial production of pigments. These natural pigments are widely used in the textile, food, pharmaceutical and cosmetic industries.
Workflow of Our Service
References
- Arikan, E. B.; et al. Production of Bio-Based Pigments from Food Processing Industry By-Products (Apple, Pomegranate, Black Carrot, Red Beet Pulps) Using Aspergillus carbonarius. Journal of Fungi - Open Access Mycology Journal. 2020. 6(4): 240.
- Silbir, S.; Goksungur, O. Natural Red Pigment Production by Monascus Purpureus in Submerged Fermentation Systems Using a Food Industry Waste: Brewer's Spent Grain. Foods. 2019. 8(5): 161.
