Ecological and Biotechnological Aspects of Pigmented Microbes: A Way Forward in Development of Food and Pharmaceutical Grade Pigments

Abstract

Microbial pigments play multiple roles in the ecosystem construction, survival, and fitness of all kinds of organisms. Considerably, microbial (bacteria, fungi, yeast, and microalgae) pigments offer a wide array of food, drug, colorants, dyes, and imaging applications. In contrast to the natural pigments from microbes, synthetic colorants are widely used due to high production, high intensity, and low cost. Nevertheless, natural pigments are gaining more demand over synthetic pigments as synthetic pigments have demonstrated side effects on human health. Therefore, research on microbial pigments needs to be extended, explored, and exploited to find potential industrial applications. In this review, the evolutionary aspects, the spatial significance of important pigments, biomedical applications, research gaps, and future perspectives are detailed briefly. The pathogenic nature of some pigmented bacteria is also detailed for awareness and safe handling. In addition, pigments from macro-organisms are also discussed in some sections for comparison with microbes.

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

“…The global market of carotenoids growing at a compound annual growth rate (CAGR) of 2.6% is expected to reach 2 billion dollars by 2027 ( Mussagy et al, 2021 ). However, the chemical synthesis constitutes 80–90% of carotenoids supply for the market and hence, to counter their side-effects, the microbial sources are gaining high demand ( Saini and Keum, 2019 ; Chatragadda and Dufossé, 2021 ). Though some companies such as Cyanotech (United States), Algatech (Israel), and Parry Nutraceuticals (India) have started producing carotenoids by biotechnological route, their market share is substantially smaller than synthetic producers ( Mussagy et al, 2021 ).…”

“…The plentiful pigments produced by the microbial world have widespread applications in different industrial sectors ( Narsing Rao et al, 2017 ; Chatragadda and Dufossé, 2021 ; Orlandi et al, 2021 ; Rana et al, 2021 ). The characteristic bioactivities of these secondary metabolites endow them with peculiar functional attributes which can be exploited for tailored applications via biotechnological tools ( Figure 2 ).…”

“…Nevertheless, by chemical definitions, pigments are insoluble colored substances while colorants are soluble colored substances ( Rana et al, 2021 ). By 2027, the market value of dyes and pigments is expected to reach 33.2–49.1 billion dollars ( Chatragadda and Dufossé, 2021 ). Though synthetic petro-derived colorants have dominated the industries due to low cost and high yield, the rising concerns about their non-biodegradability, carcinogenicity, and environmental toxicity have enthused both industry and researchers to find natural and safe alternatives.…”

Recent Findings in Azaphilone Pigments

“…As aforementioned, another approach to achieve yield improvement and consequently increase the viability of industrial production of fungal metabolites is the use of mutant strains and genetic engineering [ 99 ]. The current knowledge of the metabolic pathways and secondary metabolism precursors allow to manipulate fungi as “real industrial cell factories” [ 103 ] and take advantage of the entire pigment gene cassette to improve pigment yield [ 104 ]. In this way, Liu et al [ 99 ] managed to knock-out a cAMP phosphodiesterase gene in M. purpureus HJ11, which led to the accumulation of intracellular cAMP causing a stimulating effect in secondary metabolism that resulted in 2.3-fold increase in pigment production.…”

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

“…Pigments are biosynthesized through various pathways dependent on both the genetics of the organism and may be contained within cells or diffuse throughout surrounding media [ 32 ]. Most microbial pigments are termed “secondary metabolites”, as they are byproducts of biosynthesis but are not required for necessary functions such as growth and reproduction [ 33 ].…”