Ameliorating process parameters for zeaxanthin yield in Arthrobacter gandavensis MTCC 25325

Carotenoid pigments of Kocuria flava PUTS1_3 isolated from sediments of Puttalam lagoon mangrove ecosystem, Sri Lanka exhibit bioactive properties

Microorganisms, inhabiting various ecological niches, exhibit a capacity to produce a diverse array of pigments with different shades. These colorful microbial pigments may also potentially possess beneficial bioactivities. This dual functionality together with the ease of mass production and downstream processing has shifted the global attention towards the use of microbially-derived pigments as bioactive colorants in different industries. Therefore, the present study was conducted with the aim of characterizing the pigments from Kocuria flava and identifying their potential biotechnological applications. The bacterium, PUTS1_3, was isolated using the surface sediment samples from the Puttalam mangrove ecosystem, Sri Lanka and it was identified as Kocuria flava using 16S rRNA gene sequencing. The yellow, intracellular pigment of PUTS1_3 was obtained by treating the cell pellet with methanol. Characterization of the pigment extract using UV-visible spectroscopy, TLC, and HPLC confirmed the presence of three carotenoid compounds, including β-carotene. The pigment extract also demonstrated antibacterial activity, against Gram positive bacteria tested. Antioxidant properties were observed with an IC50 value of 181.95 ± 4.57 µg/ml in the DPPH free radical scavenging assay. Although its sun protection factor was comparatively low (SPF 7.69 ± 0.01), the pigment showed promising results as a textile dye demonstrating good color performance and stability in washing and pH stability tests. Moreover, fabrics dyed with the pigment extract displayed antibacterial activity against Staphylococcus aureus (ATCC 25923). These findings suggest the potential use of the yellow pigments of K. flava PUTS1_3 for various biotechnological applications.

Sphingomonas arvum sp. nov.: A promising microbial chassis for high-yield and sustainable zeaxanthin biomanufacturing

The yield of natural products from plants is currently insufficient and cannot be considered a sustainable and secure source of supply, especially given the challenges posed by global climate change. Therefore, a biofoundry that can quickly and accurately produce desired materials from microorganisms based on synthetic biology is urgently needed. Moreover, it is important to find new microbial and genetic chassis to meet the rapidly growing global market for high-value-added zeaxanthin. In this study, we aimed to identify the zeaxanthin biosynthetic gene cluster, crtZ-crtB-crtI-crtY, and confirm zeaxanthin production (11,330 μg g-1 dry biomass weight) through genome mining and liquid chromatography/mass spectrometry profiling using the novel zeaxanthin-producing bacteria Sphingomonas sp. strain BN140010T isolated from the subsurface soil of arable land. We report the highest yield among zeaxanthin-producing Sphingomonas strains to date. Moreover, we determined the taxonomic position of BN140010T using a polyphasic approach based on phylogenetic, physiological and chemotaxonomic characteristics, and we proposed Sphingomonas arvum strain BN140010T as a novel strain. Our results provide a zeaxanthin-producing chassis and diverse genetic tools for microbiological zeaxanthin production. Therefore, this research advances our progress towards the goal of lowering the unit cost of zeaxanthin production, making it more accessible for industrial applications.

Screening of novel β-carotene hydroxylases for the production of β-cryptoxanthin and zeaxanthin and the impact of enzyme localization and crowding on their production in Yarrowia lipolytica

Zeaxanthin, a vital dietary carotenoid, is naturally synthesized by plants, microalgae, and certain microorganisms. Large-scale zeaxanthin production can be achieved through plant extraction, chemical synthesis, or microbial fermentation. The environmental and health implications of the first two methods have made microbial fermentation an appealing alternative for natural zeaxanthin production despite the challenges in scaling up the bioprocess. An intermediate between β-carotene and zeaxanthin, β-cryptoxanthin, is found only in specific fruits and vegetables and has several important functions for human health. The low concentration of β-cryptoxanthin in these sources results in low extraction yields, making biotechnological production a promising alternative for achieving higher yields. Currently, there is no industrially relevant microbial fermentation process for β-cryptoxanthin production, primarily due to the lack of identified enzymes that specifically convert β-carotene to β-cryptoxanthin without further conversion to zeaxanthin. In this study, we used genetic engineering to leverage the oleaginous yeast Yarrowia lipolytica as a bio-factory for zeaxanthin and β-cryptoxanthin production. We screened 22 β-carotene hydroxylases and identified eight novel enzymes with β-carotene hydroxylating activity: six producing zeaxanthin and two producing only β-cryptoxanthin. By introducing the β-carotene hydroxylase from the bacterium Chondromyces crocatus (CcBCH), a β-cryptoxanthin titer of 24 ± 6 mg/L was achieved, representing the highest reported titer of sole β-cryptoxanthin in Y. lipolytica to date. By targeting zeaxanthin-producing β-carotene hydroxylase to the endoplasmic reticulum and peroxisomes, we increased the production of zeaxanthin by 54% and 66%, respectively, compared to untargeted enzyme. The highest zeaxanthin titer of 412 ± 34 mg/L was achieved by targeting β-carotene hydroxylases to peroxisomes. In addition, by constructing multienzyme scaffold-free complexes with short peptide tags RIDD and RIAD, we observed a 39% increase in the zeaxanthin titer and a 28% increase in the conversion rate compared to the strain expressing unmodified enzyme. The zeaxanthin titers obtained in this study are not the highest reported; however, our goal was to demonstrate that specific approaches can enhance both titer and conversion rate, rather than to achieve the maximum titer. These findings underscore the potential of Y. lipolytica as a promising platform for carotenoid production and provide a foundation for future research, where further optimization is required to maximize production.

A Review of the Chemistry and Biological Activities of Natural Colorants, Dyes, and Pigments: Challenges, and Opportunities for Food, Cosmetics, and Pharmaceutical Application

Natural pigments are important sources for the screening of bioactive lead compounds. This article reviewed the chemistry and therapeutic potentials of over 570 colored molecules from plants, fungi, bacteria, insects, algae, and marine sources. Moreover, related biological activities, advanced extraction, and identification approaches were reviewed. A variety of biological activities, including cytotoxicity against cancer cells, antioxidant, anti-inflammatory, wound healing, anti-microbial, antiviral, and anti-protozoal activities, have been reported for different pigments. Considering their structural backbone, they were classified as naphthoquinones, carotenoids, flavonoids, xanthones, anthocyanins, benzotropolones, alkaloids, terpenoids, isoprenoids, and non-isoprenoids. Alkaloid pigments were mostly isolated from bacteria and marine sources, while flavonoids were mostly found in plants and mushrooms. Colored quinones and xanthones were mostly extracted from plants and fungi, while colored polyketides and terpenoids are often found in marine sources and fungi. Carotenoids are mostly distributed among bacteria, followed by fungi and plants. The pigments isolated from insects have different structures, but among them, carotenoids and quinone/xanthone are the most important. Considering good manufacturing practices, the current permitted natural colorants are: Carotenoids (canthaxanthin, β-carotene, β-apo-8'-carotenal, annatto, astaxanthin) and their sources, lycopene, anthocyanins, betanin, chlorophyllins, spirulina extract, carmine and cochineal extract, henna, riboflavin, pyrogallol, logwood extract, guaiazulene, turmeric, and soy leghemoglobin.

Potential of Sorghum Polyphenols to Prevent and Treat Alzheimer's Disease: A Review Article

Alzheimer's disease (AD) is characterized by the excessive deposition of extracellular amyloid-beta peptide (Aβ) and the build-up of intracellular neurofibrillary tangles containing hyperphosphorylated tau proteins. This leads to neuronal damage, cell death and consequently results in memory and learning impairments leading to dementia. Although the exact cause of AD is not yet clear, numerous studies indicate that oxidative stress, inflammation, and mitochondrial dysfunction significantly contribute to its onset and progression. There is no effective therapeutic approach to stop the progression of AD and its associated symptoms. Thus, early intervention, preferably, pre-clinically when the brain is not significantly affected, is a better option for effective treatment. Natural polyphenols (PP) target multiple AD-related pathways such as protecting the brain from Aβ and tau neurotoxicity, ameliorating oxidative damage and mitochondrial dysfunction. Among natural products, the cereal crop sorghum has some unique features. It is one of the major global grain crops but in the developed world, it is primarily used as feed for farm animals. A broad range of PP, including phenolic acids, flavonoids, and condensed tannins are present in sorghum grain including some classes such as proanthocyanidins that are rarely found in others plants. Pigmented varieties of sorghum have the highest polyphenolic content and antioxidant activity which potentially makes their consumption beneficial for human health through different pathways such as oxidative stress reduction and thus the prevention and treatment of neurodegenerative diseases. This review summarizes the potential of sorghum PP to beneficially affect the neuropathology of AD.