Bacterial pigments as sustainable and functional colorants in cosmetic applications: advances and prospects

1 Introduction

The history of dyeing dates back to the Indus Valley civilization, approximately 2600–1900 BC, showing the interest of humans in color. Before the 19th century, most of the dyes were natural and curated from fruits, plants, and berries using various techniques (Alegbe and Uthman, 2024). In 1850, the first synthetic dye was produced, and almost 80 different synthetic dyes were produced and used in different sectors by the 1900s (Rather et al., 2023). The great industrial revolution had quickly turned the attention toward synthetic dyes due to their cheaper cost and availability with limited understanding of their long-term effect. Although synthetic dyes are known to be carcinogenic and harmful, at present, they are widely used in food, textile, agricultural, and cosmetic products (Cheng et al., 2022). The presence of synthetic dyes in cosmetic products is a well-known fact. Human skin is a very sensitive organ that loses moisture and elasticity over time. Constant exposure to ultraviolet (UV) light and chemicals can result in faster aging of the skin. Thus, skin care is important to maintain its barrier function (Resende et al., 2021). The synthetic dyes present in cosmetic products have many harmful effects such as skin damage and tumor formation. Heavy metals such as chromium and cadmium are found in cosmetic products like lipsticks, eye shadow, eyeliner, and blush, which can lead to skin allergies, blindness, and even death (Cheng et al., 2022). These carcinogenic compounds are absorbed by the skin and act as neurotoxins, endocrine disruptors, and mutagens, affecting reproductive and overall human health. According to Wijesekara and Xu (2024), several synthetic colorants approved by the Food and Drug Administration (FDA) were found to be carcinogenic. Furthermore, in addition to skin contact, humans are also exposed to synthetic dyes through contaminated water and the food chain. These dyes trigger allergies, asthma, dermatitis, central nervous system disorders, organ dysfunction, and cancer risks. The bioaccumulation of these dyes in fish fatty tissues poses zoonotic threats (Sudarshan et al., 2023). Environmental contamination from these dyes is caused by the discharge of wastewater from various industries, including the textile and cosmetic industries. In the aquatic system, these dyes exhibit carcinogenic and mutagenic properties along with high biological oxygen demand and chemical oxygen demand (Srivastava et al., 2022). These dyes also reduce light penetration in waterways, thus inhibiting microalgae photosynthesis, causing growth inhibition, ecosystem collapse, and toxicity to fish (Krishna Moorthy et al., 2021).

Natural pigments are usually not harmful but are more expensive than the synthetic ones. Lately, there is a growing concern among consumers of skin care products regarding the safety and increasing demand for natural pigments, which are not harmful to the skin (Mary et al., 2024). The advantage of natural pigments is their antioxidant and antimicrobial properties, which boost their demand in the market. The market demand for natural pigments has grown to nearly 2.5 billion USD in 2025 and is expected to increase to approximately 55 billion USD by 2027 (Anshi et al., 2024). The need for bio-based, less harmful, and high-performance colorants has driven the demand for natural pigments. The ever-expanding cosmetic industry requires numerous sources of natural pigments (Agarwal et al., 2023). The growing demand for natural pigments in Asia is mainly due to industrialization and increasing population, and the demand for natural pigments is also increasing equally in European and American markets. Carotenoids are one of the pigments most widely used across food, cosmetics, medicine, textiles, beverages, and dietary supplements. The global demand remains high at 23.5% in 2023, and 80%–90% of the carotenoids present in the market are synthetic in nature (Abdelaziz et al., 2023). There are a few microbial-sourced pigments already on the market, such as riboflavin, alpha-carotene, and astaxanthin from Eremothecium gossypii, Bacillus trispora, and Xanthophyllomyces dendrorhous, respectively. The extraction of natural pigments from novel sources and their application have gained momentum among researchers at present (Kharkhota et al., 2022).

Pigments derived from microbes are identified as microbial pigments that bear health benefits for humans through essential nutrient supply, and their antimicrobial, anti-inflammatory, and anticancer activities are an added advantage (Di Salvo et al., 2023). Their low cost, durability, sustainability, availability, environment-friendly nature, and numerous sources and applications across various industries are some of the reasons for their high demand (Dufossé, 2019). Microbes produce a range of pigments to adapt to the ecosystem, exhibiting unique characteristics like protection against solar or UV radiation. Even though fungi, microalgae, and yeast produce pigments, bacteria-derived pigments attract the majority of the market due to their abundance and ready availability (Singh et al., 2021). Quinones, melanin, flavin, monascine, carotenoids, phenazines, and violacein are some of the examples of bacterial pigments with provitamin A and antitumor activity and temperature, pH, and photostability (Rather et al., 2023). Serretia mercescens produces the red-colored pigment prodigiosin with anticancer and antimicrobial activity in the presence of glucose and glycine. Dietzia natronolimnaea HS-1 produces the dark red-colored canthaxanthin used in the pharmaceutical, food, and cosmetic industries using cheese whey as a substrate, while Duganella sp., Janthinobacterium lividum, and Chromobacterium sp. produce the purple-colored violacein pigment that exhibits antitumoral, antioxidant, antiparasitic, and immunomodulatory activities. While red and yellow pigments are abundantly produced by several bacteria, only a few bacteria can produce blue pigments. Corynebacterium insidiosum produces indigoidine, which is blue in color and exhibits protection against oxidative stress. The blue-green color pigment pyocyanin, which helps in reducing inflammation, is produced by Pseudomonas aeruginosa (Venil et al., 2020).

The Green Revolution has hit the cosmetic industry, advocating for health and safety and introducing a term called cosmeceuticals. It offers a new perspective besides beauty and attracts vibrant business ideas. In addition to their antioxidant and antiaging effects, bacterial pigments offer vibrant colors in cosmetic products (Pagels et al., 2022). Sun damage to the skin leads to wrinkles, aging, and even skin cancer. Regular sunblock products available in the market absorb UV rays rather than reflecting them, causing allergies and skin irritation (Mendes-Silva et al., 2020). Carotenoids curated from bacteria have gained attraction due to their anti-UV properties and antioxidant activities, causing less skin damage by reducing free radical production. It can be used as a natural sunscreen replacing chemical ingredients (Terao, 2023). Beta-carotene, lycopene, and astaxanthin are some of the naturally sourced carotenoid pigments. Antiaging creams are one of the most popular skin care products, and consumers are turning toward natural components (Chavda et al., 2023). The study by Kiki (2023) showed that beta-cryptoxanthin from Dunaliella salina and lycopene from Anabaena vaginicola can stimulate hyaluronic acid production, increasing skin hydration. Haematococcus pluvialis produces astaxanthin, which is known to improve skin moisture content, texture, and wrinkles (Liu, 2022). Japanese and Swedish skin care companies have marketed products containing astaxanthin for antiaging solution. Skin whitening creams are also very popular among Asian countries (Pollock et al., 2021). Tyrosinase inhibitors lead to decreased melanin production, catalyzing the pigmentation process. These compounds are being used to treat albinism. Fucoxanthin from Laminaria japonica and astaxanthin from Haematococcus pluvialis are superior antioxidants due to their catalase and superoxide dismutase capabilities. Topical and oral astaxanthin can improve hyperpigmentation problems by stopping melanin production (Araújo et al., 2021). Chemicals like benzene and toluene are used for the vibrant colors of lipsticks and nail polish, which can be replaced by bacterial pigments offering safety and stability (Kalra et al., 2020). Marine microbes are being extensively studied for their cosmetic applications. Phycocyanin from marine algae is being used in eye shadow and eye makeup. Pigments extracted from red microalgae are used in red, purple, and pink lipstick and eye makeup (Yarkent et al., 2020). Microbial pigments from several environmental niches have attracted attention and are being studied for their use in the cosmetic industry. This review intends to explore the classification and biosynthetic pathways of bacterial pigments, highlighting the scope of genetic engineering for the enhanced production of pigments. It explores the use of bacterial pigments in cosmetic products and their advantages. This review also discusses the recent advances and technological innovations in pigment production from different bacterial sources. The challenges, limitations, and future perspectives of the revolutionary role of bacterial pigments in the cosmetic industry are also explored in this study.

2 Bacterial pigments

Bacterial pigments are characterized as diverse metabolites, which are generated by various microbial species. These pigments impart characteristic colors, but they also play physiological, ecological, and industrial roles. The broad classification of bacterial pigments is mainly based on color, chemical nature, biological function, and solubility (Agarwal et al., 2023).

2.1 Classification of bacterial pigments

2.1.1 Carotenoids

Carotenoids are yellow, red, or orange pigments that mainly protect bacterial species from oxidative stress. Micrococcus luteus and Serratia marcescens produce carotenoids (yellow color) and prodigiosin (red color), respectively. Carotenoids are isoprenoid compounds that are normally lipid-soluble (López et al., 2023).

2.1.2 Melanin

These are black or darkish brown, which are generated through phenolic compound oxidation. Melanin normally protects bacteria from free radicals, enzymatic lysis, and UV radiation. Some of the bacteria that produce melanin are Vibrio cholerae and Shewanella colwelliana (Celedón and Díaz, 2021; Thakur et al., 2025).

2.1.3 Quinones

These pigments usually work as electron carriers during bacterial respiration and photosynthesis. Some of the common quinones in bacterial species are menaquinones, ubiquinones, chlorobiumquionones, and rhodoquinones. Some of the common bacteria that produce these pigments are Escherichia coli (ubiquinones), P. aeruginosa (ubiquinones), and Staphylococcus aureus (menaquinones) (Celedón and Díaz, 2021).

2.1.4 Phenazine pigments

These are heterocyclic pigments possessing antimicrobial properties. The most common examples are pyocyanin (blue green) and pyorubin (red pigment), which are produced by P. aeruginosa. Also, these pigments act as electron carriers in redox reactions (Abdelaziz et al., 2023).

2.1.5 Other pigments

Certain bacteria generate unique pigments that do not fit into any of the above classifications, and examples include Janthinobacterium lividum, which produces violacein (purple color), and Streptomyces coelicolor, which produces actinorhodin (blue color) (Lyakhovchenko et al., 2024).

2.1.6 The Indian Himalayan region as a source of pigment-producing bacteria

Although the high-altitude Himalayan region visibly looks barren and lifeless, beneath its surface, rich and diverse microbial communities are found. These trans-Himalayan niches experience environmental stresses such as fluctuating temperatures, extreme cold, frequent freeze–thaw cycles, oxidative stress, high UV radiation, low oxygen levels, and low nutrient availability. The pigment production in the microbes of this region is considered an important adaptive strategy against these extreme conditions. There are a number of pigment-producing bacteria that have been identified from this region, and these are illustrated in Figure 1. The list of pigment-producing bacteria/phyla is summarized in Table 1.

Table 1. List of pigment-producing bacteria/phyla along with pigment name.

2.2 Biosynthetic pathways of pigment production in bacteria

Bacteria generate various pigments through special biosynthetic pathways, which originate from primary metabolic intermediates. The biosynthetic pathways are often regulated by environmental and genetic factors. Understanding bacterial biosynthetic pathways is crucial in aiding metabolic engineering for enhanced pigment synthesis. Several biosynthetic routes differ on the basis of the chemical nature of the pigment (Agarwal et al., 2023; Barreto et al., 2023).

2.2.1 Biosynthesis of carotenoids

The synthesis of carotenoids begins with isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) condensation, to form geranylgeranyl pyrophosphate (GGPP). Two molecules of geranylgeranyl pyrophosphate combine to form phytoene, which later undergoes cyclization and desaturation reactions, producing carotenoids such as lycopene, zeaxanthin, and β-carotene. Certain bacteria such as Rhodobacter spp. and M. luteus follow this biosynthetic pathway (Wang et al., 2024).

2.2.2 Biosynthesis of phenazine

Pigments such as pyocyanin are generated in P. aeruginosa through the shikimate pathway. Chorismic acid functions as a key intermediate and undergoes various enzymatic reactions, which is catalyzed by the phz (phenazine biosynthetic) gene cluster. This leads to the production of phenazine-1-carboxylic acid (PCA), which can be later modified into pyorubin and pyocyanin (Abdelaziz et al., 2023).

2.2.3 Biosynthesis of melanin

Melanin is formed through oxidation of tyrosine, with the help of the enzyme tyrosinase, leading to the generation of dopaquinone, which gradually polymerizes into dark melanin. Certain other bacteria produce melanin through the 1,8-dihydroxynaphthalene (DHN) or homogentisate pathways (Pavan et al., 2020).

2.2.4 Biosynthesis of prodigiosin

Serratia marcescens synthesizes the red pigment prodigiosin through the tripyrrole pathway. 2-Methyl-3-n-amyl-pyrrole and 4-methoxy-2,2′-bipyrrole-5-carboxyaldehyde are the two intermediates formed in this pathway. These two intermediates are condensed with the help of certain enzymes to produce prodigiosin (Williams, 1973).

2.2.5 Biosynthesis of violacein

Chromobacterium violaceum synthesizes violacein from the amino acid tryptophan. The amino acid tryptophan is converted into indole derivatives using an enzyme coded by the vioABCDE gene cluster. Indole derivatives gradually undergo oxidative coupling in order to form violacein (Hui et al., 2022).

2.3 Genetic and metabolic engineering approaches for enhanced pigment production

Most of the bacterial pigments such as carotenoids, melanin, and violacein have significant applications in the cosmetic, pharmaceutical, textile, and food industries (Sundar and Sivaperumal, 2022). However, natural pigment production is mostly limited due to low yields, suboptimal metabolic fluxes, and regulatory constraints. In order to overcome these, genetic and metabolic engineering approaches are employed nowadays to enhance the biosynthesis of bacterial pigments (Lee and Schmidt-Dannert, 2002).

2.3.1 Genetic engineering

This includes direct manipulation of bacterial pigment-producing genes and metabolic pathways. Some of the techniques such as heterologous expression, gene deletion, and overexpression have transformed pigment biosynthesis. In case of gene overexpression, genes controlling rate-regulating enzymes are amplified to increase bacterial pigment yield. For instance, in Rhodobacter sphaeroides, overexpression of the crtY gene increases β-carotene synthesis. An overview of the promoter optimization strategy is shown in Figure 2 (Qiang et al., 2019). In another work, from C. violaceum, overexpression of the genes vioA–E increases the violacein production in E. coli (Balibar and Walsh, 2006). In this mechanism, VioA (flavoenzyme) and VioB (heme protein) cooperatively oxidize and dimerize L-tryptophan to result in an intermediate that can yield chromopyrrolic acid off-pathway. VioE presence precedes the reaction via [1,2]-indole rearrangement to prodeoxyviolacein. The final flavin-dependent oxygenases, VioD and VioC, sequentially hydroxylate and oxidize the indole rings at positions 5 and 2, respectively, completing violacein biosynthesis.

In another study, transcription factor and promoter engineering was performed to enhance prodigiosin production in Serratia marcescens JNB5-1 (Pan et al., 2022). In this study, first, a Tn5G transposon insertion library identified the response regulator BVG89_19895 (OmpR) as a positive regulator of prodigiosin synthesis. Thereafter, RNA-Seq, GFP reporter, and RT-qPCR analyses revealed the promoter P17 (P_RplJ) as a strong constitutive promoter. Overexpression of OmpR and PsrA in the strain JNB5–1 generated a recombinant strain PG-6. The generated recombinant strain achieved a prodigiosin titer of 10.25 g/L, which was 1.62-fold higher than the parent strain (6.33 g/L).

2.3.2 Metabolic engineering approaches

The rise in the demand for carotenoid pigments has laid the foundation for the increased production of these pigments through metabolic engineering of their biosynthesis pathways. The first attempt for lycopene production was carried out in a fungus (S. cerevisiae) with the carotenogenic genes of the Eubacterium Pantoea ananatis (Yamano et al., 1994). However, considerable efforts have been made in the metabolic engineering of E. coli to produce carotenoids (lycopene, β-carotene, and zeaxanthin) at a higher titer (Das et al., 2007). Escherichia coli has been observed as a choice of host for the heterologous carotenoid production due to the fact that it can accommodate and express the carotenogenic genes from bacteria, fungi, and plants. In this context, the improved production of carotenoid in E. coli has been achieved through metabolic engineering of the endogenous MEP (2-C-methyl-D-erythritol4-phosphate) pathway and through introducing a heterologous mevalonate (MVA) pathway. The engineering of these pathways is intended to increase the intracellular supply of isopentenyl diphosphate (IPP), which is a key precursor for carotenoid biosynthesis. Furthermore, improvements in carotenoid production have been made by engineering the prenyl diphosphate and central metabolic pathways (Lee and Schmidt-Dannert, 2002). The MVA and MEP pathways begin with substrates, viz., acetyl-CoA, pyruvate, and glyceraldehyde-3-phosphate (G3P), produced in the glycolytic pathway (Figure 3). Therefore, regulating the production of these metabolites can improve carotenoid production. Pyruvate is considered a more crucial precursor, as it finds itself in multiple metabolic routes and is more abundant than G3P for isoprenoid biosynthesis. The MEP pathway utilizes pyruvate and G3P in equal amounts for IPP synthesis. Hence, modulation of these intermediate enzymes can alter the metabolic flux between these intermediates to enhance lycopene production in E. coli (Farmer and Liao, 2001). In these studies, it was observed that G3P is a limiting factor in lycopene biosynthesis. Therefore, inactivation of the competing pathways branching at the pyruvate and acetyl-CoA nodes increases 45% of lycopene production in the engineered E. coli strain as compared to the parent E. coli strain (Vadali et al., 2005). Production was further improved by incorporating the MVA pathway from the Streptomyces sp. strain CL190 into the E. coli strain (inactivated). This bioengineering fostered the acetyl-CoA pool for IPP synthesis, which eventually resulted in a 2-fold increase in lycopene production as compared to the native MEP pathway. In another study, the co-expression of the exogenous MEP pathway genes (dxs and idi) in E. coli promoted the transcription of isoprenoid pathway genes (Wang et al., 2015). In this case, there was a 16.5 times increase in the yield (20.57 mg/L) of lycopene.

Introduction of a heterologous MVA pathway into E. coli represents a promising strategy for enhancing carotenoid biosynthesis. The MVA pathway can be functionally divided into two segments: the upper (top) and lower (bottom) pathways. The final step of the upper pathway, catalyzed by HMG-CoA reductase, serves as a rate-limiting step in the process. In this regard, promoter-driven overexpression of the cHMG1 gene from S. cerevisiae in Neurospora crassa has been shown to increase the production of lycopene and neurosporaxanthin (Wang and Keasling, 2002). Similarly, E. coli has also been metabolically engineered for the co-overexpression of crtY, crtZ, and ZEP encoding the enzymes lycopene β-cyclase, β-carotene 3-hydroxylase, and zeaxanthin epoxidase, respectively (Xinrui et al., 2023). The engineered strain was able to produce a violaxanthin yield of 25.28 ± 3.94 mg/g DCW along with a lowering in the accumulation of by-products. Cheng et al. (2022) introduced the heterologous lycopene biosynthetic pathway into E. coli, and this was organized into three modules. In the modules, MVA and dimethylallyl pyrophosphate (DMAPP) acted as connecting intermediates. The intermodule balance was optimized by controlling the expression level of the genes, viz., MVK, PMK, MVD, and IDI (involved in downstream), through a ribosome binding site library with defined expression strengths. The bioengineering resulted in 4.6 times more yield of lycopene (219.7 mg/g DCW) as compared to the reference strain.

2.3.3 Synthetic biology and advanced engineering tools

CRISPR/Cas9 is an exciting technology for bioengineering the metabolic pathway of bacteria for desired applications. However, it has been less explored for pigment production in bacteria. CRISPR has been used to enhance β-carotene production from the IPP and dimethylallyl pyrophosphate (DMAPP) through the MEP pathway. The technology has been used to engineer the central metabolic routes and regulate the metabolic fluxes by targeted gene deletions and strategic gene overexpression (Cho et al., 2018). In another work, E. coli strains possessing the biosynthetic MVA pathway and terpenoid synthases (plant-derived) have been engineered using the CRISPR interference (CRISPRi) system for suppressing the expression of acetoacetyl-CoA thiolase enzyme. This enzyme is responsible for catalyzing the first step of the MVA pathway (Kim et al., 2016). This bioengineering has been observed to enhance the production of (−)-α-bisabolol (C15) and lycopene (C40). Furthermore, it also mitigated cell growth inhibition and accumulation of toxic intermediates within the MVA pathway. Similarly, CRISPRi-based library targeting of 74 genes was done in Corynebacterium glutamicum (Göttl et al., 2021). The results indicated that CRISPRi-mediated repression of the carotenogenesis repressor gene crtR led to enhanced pigmentation and increased accumulation of the native carotenoid pigment decaprenoxanthin. CRISPRi screening identified 14 genes whose repression influenced decaprenoxanthin biosynthesis. Out of the 14 genes identified, repression of 11 genes reduced carotenoid production, and repression of 3 genes promoted decaprenoxanthin synthesis. Furthermore, deletion of pgi and gapA genes enhanced decaprenoxanthin production by 43- and 9-fold, respectively. Another study utilized the CRISPR/Cas9-based genome editing system for actinomycetes for two chromogenic reporter systems (GusA and IdgS) (Göttl et al., 2021). The researchers deleted a single gene, i.e., actIORFI (SCO5087 of the actinorhodin gene cluster), in S. coelicolor M145. They also deleted the small gene cluster of 5.5 kb responsible for orange-pigmented carotenoid production and a relatively large gene cluster (61 kb) corresponding to the abyssomicin biosynthetic pathway in Verrucosispora sp. MS100137.

3 Applications in cosmetic formulations

3.1 Cosmetic products incorporating bacterial pigments

Biodegradability, stability, and bioactivity have placed bacterial pigments in the spotlight as alternatives to synthetic dyes in the cosmetics sector and as being environmentally friendly, sustainable, and natural (Barreto et al., 2023). These pigments are incorporated into a broad category of cosmetic products such as lipsticks, skin creams and lotions, nail polishes, hair dyes, soaps, and body washes.

3.1.1 Lipsticks, nail polishes, and hair dyes

Microbial carotenoids and prodigiosin-like pigments have color intensities ranging between red and orange. These pigments can be natural alternatives to azo dyes (Devi et al., 2024). Their high coloring intensity along with their antioxidant activity can be the reason for their acceptance in lip care applications. Furthermore, these natural pigments reduce the risk of direct skin contact and ingestion of synthetic chemicals, hence are biocompatible (Huang et al., 2024b). Similarly, these microbial pigments can also be used for nail polishes, as they cover a broad range of colors. These natural pigments derived from bacteria are biocompatible, and their use in place of chemical-based nail polishes can help minimize adverse effects associated with synthetic colorants. Furthermore, these colors could be the best option for the manufacturing of natural hair colors.

3.1.2 Skin creams and lotions

It is well known that UV radiation from the sun can lead to adverse health effects such as pigmentation, erythema, immunosuppression, photoaging, and even skin cancer (Choksi et al., 2020). Therefore, sunscreens are commonly used to protect the skin from UV rays. Most sunscreens in the market utilize chemicals for the screening of these UV rays, but due to the growing awareness and demand for natural alternatives in recent years, there is a need for natural and effective pigments for skin products. Researchers are also focusing on identifying new, cost-effective natural sunscreen agents from bacterial and other natural sources (Goswami et al., 2013). There are a number of microorganisms that produce pigments and provide protection against UV-induced damage (Suryawanshi et al., 2015). Bacterial pigments such as prodigiosin, violacein, and melanin have been reported by various research groups for their strong UV-protective effect (Siezen, 2011; Darshan and Manonmani, 2015; Kothari et al., 2017). These pigments also exhibit strong antioxidant activity, making them suitable for incorporation into creams and lotions to enhance skin protection. In a study, the bacterium Virgibacillus salarius strain 19.PP.Sc1.6 has been identified for carotenoid production (Kusmita et al., 2021). The carotenoid pigments from the bacterium were utilized in the development of antiaging creams and demonstrated significant antiaging activity.

3.1.3 Soaps and body washes

Soaps and body washes have not been documented with bacterial pigments, but there are a few reports where fungal pigments and other plant pigments were utilized in these products. Asnani and Diastuti developed a glycerine soap utilizing the red pigment from Streptomyces K-4 B and Dayak onion (Eleutherine palmifolia (L.) Merr) (Herlina and Diastuti, 2017). The results of the developed product were assessed based on color, aroma, texture, foam, and rough impression upon usage and after usage and were observed to be in the “like to very like soap” category (score of 4.67 in the scale of 1 to 5) and “like to very like” category (score of 4.30 in the scale of 1 to 5). Additionally, bacterial glycolipids and lipopeptides have been reported for their emulsifying, detergency, foaming, and skin moisturizing capabilities. The pigments from bacteria can be an alternative to chemical colors along with their emulsifying, moisturizing, and antioxidant properties. However, this area of pigment-producing bacteria is not well established, and still a lot of biotechnological interventions that can be made.

3.2 Functional benefits beyond coloring

In addition to their ability to color, bacterial pigments have functional activities such as antioxidant, antimicrobial, and antiaging activities, which have contributed to increasing the therapeutic properties of cosmetics.

3.2.1 Antioxidant activity

Carotenoid, violacein, and prodigiosin pigments possess an effective free-radical scavenging and lipid peroxidation inhibitory effect, playing a role in photoprotection of the skin and related repair (Kiki, 2023; Devi et al., 2024). Incorporated into topical preparations, these pigments prevent oxidative stress caused by UV radiation and pollutants, hence preserving the dermal homeostasis (Venil et al., 2020).

3.2.2 Antimicrobial activities

Numerous bacterial pigments, such as prodigiosin and pyocyanin, have neutral antimicrobial activity against S. aureus, Candida albicans, and E. coli (Yusuf et al., 2017; Salman et al., 2025). In a study, Micrococcus species of bacteria isolated from soil samples were reported to produce a yellow pigment (Sinha et al., 2017). The pigments were observed for their antibacterial activity against S. aureus (23 mm), Candida (14 mm), and S. typhi (10 mm), which was comparable to penicillin (19 mm) and gentamicin (17 mm) against S. aureus. In another study, the bacterial pigment carotenoid from Rhodotorula glutinis (PTCC 5256) was able to exhibit significant antimicrobial activity against Salmonella enteritidis and E. coli (Yolmeh, 2016). Likewise, S. marcescens, C. violaceum, and P. aeruginosa were observed to produce pigments such as prodigiosin, violacein, and pyocyanin, respectively (Salman et al., 2025). These pigments have been able to inhibit the growth of 30 clinical isolates of Enterococcus faecalis, Klebsiella spp., and Candida spp.

3.2.3 Antiaging activities

Microbial pigments as antiaging bioactives reduce oxidative stress and preserve collagen integrity. Carotenoid creams and violacein emulsions increase the elasticity of the skin and inhibit photoaging by suppressing reactive oxygen species (Orlandi et al., 2022). Furthermore, they have the potential to suppress the activity of tyrosinase, creating skin-brightening effects, and thus extending their uses in antiaging and cosmeceutical collections. The bacteriochlorophyll a pigment from R. sphaeroides has been observed for its antioxidant activity of 63.8% in aqueous extract form (Kim et al., 2015). Similarly, s pigment–protein complex from Chlorella pyrenoidosa has been observed to inhibit the inflammatory cytokines TNF-α and IL-6 and inflammatory mediator nitric oxide formation in simulated conditions (Zhang et al., 2019). Likewise, carotenoid pigments from Flavobacterium sp. and Brevibacterium sp. were able to provide significant protection against UVA-B to UVC radiation (Patki et al., 2021). These pigments further exhibited good antimicrobial activity against E. coli, Corynebacterium diphtheriae, and S. aureus along with remarkable antioxidant activity. These multifunctional properties from pigment-producing bacteria show their potential use in cosmetic products. However, limited studies have been done in this field, and more research is required for its global acceptance and recognition.

4 Recent advances and technological innovations

Refinement of innate pigment-producing bacterial strains could be achieved through biotechnological (genetic engineering) strategies for short-term fermentations, giving maximal yields. This is possible through appropriate screening of the best (hyper) pigment-producing bacterial strains, targeting the genetic matter that acts as a regulator/determinant of the respective bacterial pigments (Orlandi et al., 2022). Genetic engineering of pigment-producing bacterial strains may involve random mutagenesis or specific site-directed mutagenesis to increase the desired pigment production. This strain improvement was attained using microwave (bacterial prodigiosin from S. marcescens) and ultraviolet radiations and chemicals like 1-methyl-3-nitro-1-nitrosoguanidine and ethyl methane sulfonate, to mention a few (Shrestha et al., 2025). Violacein, from the strain Pseudogulbenkiania ferrooxidans, has contributed to the cosmetic industry, with its whole genome data relied upon to better understand its biosynthesis pathway (Mehta et al., 2025). Progressive advances in the field of genetic engineering have paved the way for positive shifts in innate bacterial strains, leading to the production of pigments of interest to researchers/industrialists. To introduce a specific case, the blue pigment-producing S. coelicolor might be manipulated genetically to produce red, brilliant yellow, yellow, and orange pigments, thus being capable of generating inherent and acquired colors (pigments) (Mehta et al., 2025).

Metabolic engineering and microbial bioconversions aid fermentation microbiologists in scaling up the laboratory bioprocesses (Mandal and Majumdar, 2023). Alternative biotechnological preference focused on the augmentation of the pigment-producing strains’ culture medium with applicable stimulators, thereby physically and statistically modeling and optimizing the fermentation pathways for shorter periods and maximum bacterial pigment gains. Pardhan et al. reported the psychrotolerant Paenibacillus sp. BPW19 for the first time, which produced intracellular pink pigment and was isolated from wastewater, belonging to the Paenibacillus genus (Padhan et al., 2021). In a cost-effective (zero-energy) manner, the production of the pigment and its solvent extraction resulted in high pigment gains. In the last half decade, the pigment-producing bacterial strains’ responses to their vicinity and surroundings (microbial communications) are well-studied in terms of quorum sensing and evocation, as a model for the extra production of bacterial pigments at an industrial scale, particularly prodigiosin and violacein pigments, as well as deep blue pigments (Pantoea agglomerans) (Fujikawa and Akimoto, 2011). Gene cloning is another prominent strategy to produce positive clones of the desired pigment producers with a suitable expression vector. The effective application of bacterial pigments as colorants in cosmetics may be restrained due to weak water solubility, poor chemical stability, delicate skin absorption, and minimal bioavailability factors. Over and above that, few biopigments (biocolorants) have high molecular weight, which can hinder their penetration (permeation) into the stratum corneum (the foremost skin layer) (Venil et al., 2013). In light of the current circumstances, it becomes mandatory for an industrialist to appropriately design product delivery systems in an efficient and scientific way that allows easy and safe penetration into the skin. Such highly unstable, less bioavailable, poorly soluble biopigments need advanced tools for systematic delivery and best skin outcomes. In the recent past, bacterial pigments like astaxanthin and carotenoids were capable of defending against the aging processes, preventing skin protein degradation. To further enhance the pigment delivery process, tetraethyl orthosilicate inside lecithin vesicles formed silicified liposomes, also known as silicated phospholipids, which served as the transporters of astaxanthin in cosmetic products (Liu and Nizet, 2009; Moura-Alves et al., 2014). This combination, along with boron nitride—one of the prevailing cosmetic ingredients, gives the best blend for superior adherence to smooth skin and eventually fine-tuning the skin texture (Li et al., 2024). Such astaxanthin liposomes could be incorporated in lipsticks, concealers, and even eye skin care products (Souto et al., 2020). Following microencapsulation, nanoencapsulation, liposomes by spray drying, emulsions by spray drying, lyophilization (freeze-drying) encapsulation, hydrogel encapsulation, and co-crystallization encapsulation are popular delivery systems of bacterial pigments, universally in the case of carotenoids (Bhandari et al., 2022; Díaz-Montes, 2025). Considering economic viability, scalability, and safeness, researchers choose prevalent encapsulation methodologies with utmost care, understanding the characteristics and nature of the bacteria-derived pigments being encapsulated. The unification and implementation of the newest tools and technologies in the fields of protein engineering, systems biology, bioprocess technology for optimized yields, process engineering, high-efficiency methodologies for pigment producers’ cultivation, survival-of-the-fittest screening and genome analyses, and metabolic engineering of pigment-producing bacteria for high yields is anticipated to become all-powerful and scientifically influential (Vieira et al., 2020). Along with the advancements and innovations in biotechnology, synthetic biology, chemistry, and forthcoming metabolic engineering, the production of microbes, particularly bacteria, will enormously amplify the number of biopigments that could be produced within stipulated fermentation periods economically (Acharya et al., 2024).

5 Challenges and future perspectives

Although there are several pigment-producing microbes existing in diverse environmental conditions, the production and yield of pigments by bacteria and other microorganisms are highly dependent on factors such as pH, temperature, media constituents/substrate, seasonal climatic variations, location, habitats, and genetic constitution (Numan et al., 2018). Furthermore, the production of bacterial pigments through fermentation is affected by the bioreactors and their design, type of fermentation process, and physicochemical and biological conditions (Venil et al., 2014). The nature of pigments is highly variable, and as a result, their solubility also differs. Therefore, identifying a suitable solvent system for each pigment is essential. Since different bacteria and microbes produce pigments at varying temperatures, analyzing the thermal stability of these pigments is an important criterion that needs to be explored. Although bacterial pigments possess several properties that make them suitable for use in cosmetic products, studies on their toxicity remain limited. For global acceptance and recognition, extensive toxicological evaluations of these pigments are essential (Nainangu et al., 2025). Such studies will also help enhance their industrial demand and applications (Ramesh et al., 2019). All cosmetic pigments, including microbial pigments, fall under the U.S. FDA’s Federal Food, Drug, and Cosmetic Act (FD&C Act) and the Modernization of Cosmetics Regulation Act (MoCRA) (Alshehrei, 2024). According to these acts and regulations, it is mandatory to conduct toxicity testing, heavy metal analysis, microbiological analysis, and particle size evaluation without pre-market approval for cosmetic products. Color additives must receive specific FDA approval before their use in cosmetic products, and the microbial limit is set at 10,000 CFU/g for general topical cosmetics with the complete absence of pathogens like P. aeruginosa, S. aureus, and C. albicans. For each pigment batch, it is important to obtain the certificates of analysis from designated officials (Huang et al., 2024a). Furthermore, the product should contain a safety data sheet to provide detailed hazard information in the Globally Harmonized System format. Cosmetic products should also contain a technical specification sheet describing the physical and chemical properties of the pigments, such as color index numbers, chemical structure, solubility, and stability.

The yield of pigment produced by native bacterial strains is often very low; however, this can be enhanced by optimizing the growth conditions of bacteria. Furthermore, this yield can be improved by employing the response surface methodology in combination with artificial neural network like statistical approaches (Venil et al., 2014). Recently, transformations in technology have opened the doors for artificial intelligence and machine learning technologies for their promising use to optimize the fermentation processes (Chong et al., 2024). Short-term goals can be high-throughput strain screening from diverse environments and habitats to identify hyperproducer strains with stable, vibrant hues suitable for product development. Furthermore, exploration of extremophilic conditions to identify novel bacterial species can account for new pigments with peculiar features such as stability, bioactivity, and multifunctionality. In addition to these approaches, metabolic engineering and synthetic biology can enhance the production of bacterial pigments along with enabling the bacteria for the heterologous production of pigments. Metabolic engineering is useful in improving the precursor supply, reducing/eliminating the competing metabolic pathways, and increasing the availability of cofactors. This approach can also expand the diversity and scale of bacterial pigment production by integrating pigment-producing genes from fungi, plants, and animals. Improving bacterial strains using CRISPR/Cas and other genome editing tools can help eliminate undesired genes and enhance strain efficiency for pigment production. The adoption of a circular bioeconomy model for pigment production, emphasizing the valorization of agricultural and food-industry wastes and other low-cost substrates for bacterial pigment fermentation, can make the process more cost-effective and sustainable (Rajendran et al., 2023).

6 Conclusion

The demand for natural cosmetic products has definitely provided a strong foundation for the utilization of bacteria as a source of natural pigments. The multiple health benefits, along with the desirable properties of bacterial pigments for cosmetic products, have already been reported by several research groups. The range of colors produced by these bacteria is also quite broad. However, most of these reports are from research laboratories and are at the very initial stages of investigation. Furthermore, the yield obtained from these microorganisms is also very low. The standardization of process parameters, strain improvement, and the adoption of a sustainable approach for pigment production may provide a boost for industrial-scale recognition and global acceptance of these pigments. The research and development sector is still in a nascent stage for exploring these pigment-producing bacteria.

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Footnotes

Edited by: Barkha Singhal, Gautam Buddha University, India

Reviewed by: Luqman Jameel Rather, Southwest University, China

Dalia Dasgupta Mandal, National Institute of Technology, Durgapur, India