Titanium dioxide-mediated fatty acids promoted carotenoid synthesis in Phaffia rhodozyma PR106 analyzed whole genome

Regulation of whey protein emulsion gel's structure with pullulan to enhance astaxanthin bioaccessibility

In this study, the potential of using an emulsion gel based on whey protein concentrate (WPC) and pullulan (PUL) to encapsulate and deliver astaxanthin (AST) was investigated. PUL concentration was observed to affect the microstructure of WPC/PUL/AST emulsion gels, and the performance of emulsion gels was evaluated by encapsulation efficiency, simulated gastrointestinal digestion, storage stability, hardness, and water holding capacity tests. The WPC/PUL/AST emulsion gels had the highest encapsulation efficiency, gastrointestinal digestion retention, and bioaccessibility of (91.70 ± 1.47) %, (80.96 ± 5.02) %, and (40.69 ± 1.16) % at 2.0 % PUL concentration, respectively. Furthermore, adding PUL to the emulsion gels improved their hardness, water holding capacity, and storage stability. The findings suggested a potential method to optimize the bioaccessibility of AST in emulsion gels. It provided the possibility for the efficient application of AST as a functional food.

Advance toward function, production, and delivery of natural astaxanthin: A promising candidate for food ingredients with future perspectives

Astaxanthin (AST) exhibits potent antioxidant activity, effectively preventing neurological diseases and cancer. Presently, producing AST from microorganisms like Haematococcus pluvialis and Phaffia rhodozyma is a growing trend. This review summarizes the main research topics on AST in the past five years. AST plays a crucial role in cancer and diabetes prevention, as well as neuroprotection, however, the presence of both free and esterified forms of AST results in differences in their functionality and applications. The primary challenges in industrial production of natural AST lie in breeding high-yield natural producers and developing methods to enhance yield. The use of high-quality food matrix materials and preparation methods is crucial for the delivery system of loaded AST. This study elucidates the bottlenecks and future development directions encountered by natural AST during industrialization, aiming to promote the healthy and rapid growth of the food industry.

Energy metabolism analysis of exogenous glutamate on promoting co-accumulation of astaxanthin yield and biomass in Phaffia rhodozyma D3

Effective metabolic regulators play an essential role in regulating astaxanthin biosynthesis in Phaffia rhodozyma. In this study, it was found that 5 mM glutamate increased the astaxanthin yield and biomass of P. rhodozyma D3 to 22.34 mg/L and 6.12 g/L, which were 1.22 and 1.33 times higher than the control group, respectively. Meanwhile, glucose uptake was increased and the level of reactive oxygen species (ROS) was reduced with 5 mM glutamate. To further explore the interrelationship between glutamate and astaxanthin synthesis, the energy metabolism of P. rhodozyma D3 with and without glutamate was analysed. Glutamate promoted the Embden-Meyerhof-Parnas pathway (EMP) metabolic flux, modulated the tricarboxylic acid (TCA) cycle and the pentose phosphate pathway (PPP), activated the ornithine cycle and purine metabolism, and provided more ATP and NADPH for astaxanthin accumulation. This study clarified the possible mechanism by which glutamate promoted astaxanthin accumulation in P. rhodozyma.

Metabolomics of astaxanthin biosynthesis and corresponding regulation strategies in Phaffia rhodozyma

Astaxanthin is a valuable carotenoid and is used as antioxidant and health care. Phaffia rhodozyma is a potential strain for the biosynthesis of astaxanthin. The unclear metabolic characteristics of P. rhodozyma at different metabolic stages hinder astaxanthin's promotion. This study is conducted to investigate metabolite changes based on quadrupole time-of-flight mass spectrometry metabolomics method. The results showed that the downregulation of purine, pyrimidine, amino acid synthesis, and glycolytic pathways contributed to astaxanthin biosynthesis. Meanwhile, the upregulation of lipid metabolites contributed to astaxanthin accumulation. Therefore, the regulation strategies were proposed based on this. The addition of sodium orthovanadate inhibited the amino acid pathway to increase astaxanthin concentration by 19.2%. And the addition of melatonin promoted lipid metabolism to increase the astaxanthin concentration by 30.3%. It further confirmed that inhibition of amino acid metabolism and promotion of lipid metabolism were beneficial for astaxanthin biosynthesis of P. rhodozyma. It is helpful in understanding metabolic pathways affecting astaxanthin of P. rhodozyma and provides regulatory strategies for metabolism.

Industrially Important Fungal Carotenoids: Advancements in Biotechnological Production and Extraction

Carotenoids are lipid-soluble compounds that are present in nature, including plants and microorganisms such as fungi, certain bacteria, and algae. In fungi, they are widely present in almost all taxonomic classifications. Fungal carotenoids have gained special attention due to their biochemistry and the genetics of their synthetic pathway. The antioxidant potential of carotenoids may help fungi survive longer in their natural environment. Carotenoids may be produced in greater quantities using biotechnological methods than by chemical synthesis or plant extraction. The initial focus of this review is on industrially important carotenoids in the most advanced fungal and yeast strains, with a brief description of their taxonomic classification. Biotechnology has long been regarded as the most suitable alternative way of producing natural pigment from microbes due to their immense capacity to accumulate these pigments. So, this review mainly presents the recent progress in the genetic modification of native and non-native producers to modify the carotenoid biosynthetic pathway for enhanced carotenoid production, as well as factors affecting carotenoid biosynthesis in fungal strains and yeast, and proposes various extraction methods to obtain high yields of carotenoids in an attempt to find suitable greener extraction methods. Finally, a brief description of the challenges regarding the commercialization of these fungal carotenoids and the solution is also given.

Optimization of culture medium and scale-up production of astaxanthin using corn steep liquor as substrate by response surface methodology

Astaxanthin is a natural carotenoid with strong antioxidant activity. In this paper, the effects of carbon source, corn steep liquor, distiller grains, and initial pH on the growth and astaxanthin production of Phaffia rhodozyma D3 were evaluated. The optimal medium composition was 32 g/L glucose, 12 g/L corn steep liquor as nitrogen source, and the initial pH was 6.7. Phaffia rhodozyma D3 was cultured in a shake flask under these optimized conditions, the biomass was 6.47 g/L, the astaxanthin/OD₄₇₅ was 15.16, and the astaxanthin content was 1.41 mg/g. The astaxanthin content was further increased to 4.70 mg/g by the combination of TiO₂ stimulation and the expanding cultivation of P. rhodozyma D3 in a 5 L fermenter, which was 2.81 times that of the control group. Expanding fermentation implies the possibility of large-scale production in the astaxanthin industry. Corn steep liquor was used as an alternative nitrogen source to culture P. rhodozyma D3, which could both reduce the production cost of astaxanthin and increased the by-products utilization rate.