Biotechnological approaches for producing natural pigments in yeasts

Pigments are widely used in the food, cosmetic, textile, pharmaceutical, and materials industries. Demand for natural pigments has been increasing due to concerns regarding potential health problems and environmental pollution from synthetic pigments. Microbial production of natural pigments is a promising alternative to chemical synthesis or extraction from natural sources. Here, we discuss yeasts as promising chassis for producing natural pigments with their advantageous traits such as genetic amenability, safety, rapid growth, metabolic diversity, and tolerance. Metabolic engineering strategies and optimizing strategies in downstream process to enhance production of natural pigments are thoroughly reviewed. We discuss the challenges, including expanding the range of natural pigments and improving their feasibility of industrial scale-up, as well as the potential strategies for future development.

Study on extraction and characterization of new antibiotics violacein from engineered Escherichia coli VioABCDE-SD

To better understand the characteristic properties of violacein biosynthesized by engineered Escherichia coli VioABCDE-SD, a convenient and simplified method was designed to extract violacein and its stability, antimicrobial activity, and antioxidant capacity were analyzed. Different from the traditional extraction methods, our new method is easier and less time consuming and can directly obtain violacein dry powder product with a higher extraction rate. Low temperature, dark condition, neutral pH, reducing agents, Ba2+ , Mn2+ , Ni2+ , Co2+ , and some food additives of sucrose, xylose, and glucose were conducive to maintaining its stability. The violacein also exhibited surprisingly high bacteriostatic action against Gram-positive Bacillus subtilis, Deinococcus radiodurans R1, and Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa, but no effect on E. coli. The violacein of VioABCDE-SD exhibited strong antioxidant activity, with the scavenging rate of 1,1-diphenyl-2-picrylhydrazyl free radicals reaching 60.33%, the scavenging efficiency of hydroxyl radical scavenging reaching 56.34%, and the total antioxidant capacity reaching 0.63 U/mL. Violacein from VioABCDE-SD can be synthesized directionally with better stability, antibacterial, and antioxidant properties compared with that from the original strain Janthinobacterium sp. B9-8. Therefore, our study indicated that violacein from engineered E. coli VioABCDE-SD was a kind of new antibiotic with potential biological activities, which may have potential utility in multiple areas such as pharmacological, cosmetics, and healthy food industries.

Carotenoid Production from Microalgae: The Portuguese Scenario

Microalgae have an outstanding capacity to efficiently produce value-added compounds. They have been inspiring researchers worldwide to develop a blue biorefinery, supporting the development of the bioeconomy, tackling the environmental crisis, and mitigating the depletion of natural resources. In this review, the characteristics of the carotenoids produced by microalgae are presented and the downstream processes developed to recover and purify them are analyzed, considering their main applications. The ongoing activities and initiatives taking place in Portugal regarding not only research, but also industrialization under the blue biorefinery concept are also discussed. The situation reported here shows that new techniques must be developed to make microalgae production more competitive. Downstream pigment purification technologies must be developed as they may have a considerable impact on the economic viability of the process. Government incentives are needed to encourage a constructive interaction between academics and businesses in order to develop a biorefinery that focuses on high-grade chemicals.

Recent Advances in Synthetic, Industrial and Biological Applications of Violacein and Its Heterologous Production

Violacein, a purple pigment first isolated from a gram-negative coccobacillus Chromobacterium violaceum, has gained extensive research interest in recent years due to its huge potential in the pharmaceutic area and industry. In this review, we summarize the latest research advances concerning this pigment, which include (1) fundamental studies of its biosynthetic pathway, (2) production of violacein by native producers, apart from C. violaceum, (3) metabolic engineering for improved production in heterologous hosts such as Escherichia coli, Citrobacter freundii, Corynebacterium glutamicum, and Yarrowia lipolytica, (4) biological/pharmaceutical and industrial properties, (5) and applications in synthetic biology. Due to the intrinsic properties of violacein and the intermediates during its biosynthesis, the prospective research has huge potential to move this pigment into real clinical and industrial applications.

Multi-target drug with potential applications: violacein in the spotlight

The aim of the current review is to address updated research on a natural pigment called violacein, with emphasis on its production, biological activity and applications. New information about violacein's action mechanisms as antitumor agent and about its synergistic action in drug delivery systems has brought new alternatives for anticancer therapy. Thus, violacein is introduced as reliable drug capable of overcoming at least three cancer hallmarks, namely: proliferative signaling, cell death resistance and metastasis. In addition, antimicrobial effects on several microorganisms affecting humans and other animals turn violacein into an attractive drug to combat resistant pathogens. Emphasis is given to effects of violacein combined with different agents, such as antibiotics, anticancer agents and nanoparticles. Although violacein is well-known for many decades, it remains an attractive compound. Thus, research groups have been making continuous effort to help improving its production in recent years, which can surely enable its pharmaceutical and chemical application as multi-task compound, even in the cosmetics and food industries.