Pigment Synthesis Research Articles

Sustainable synthesis of iron oxide nanopigments: Enhancing pigment quality through combined air oxidation and cavitation techniques

This study investigates the synthesis and characterization of iron oxide pigments through various methods, including air oxidation, co-precipitation, and hydrodynamic cavitation. The infrared (IR) spectral analysis revealed key functional groups and metal-oxide bonds indicative of goethite, with bands associated with O–H stretching and Fe–O vibrations. The study also explores how different conditions, such as temperature, pH, and reactant ratios, affect the color, yield, and particle size of the pigments produced. Through batch and continuous synthesis processes, it was found that cavitation offers a more controlled particle size distribution compared to other methods. The experiments highlight the influence of parameters like temperature, pH, and NaOH concentration on the final pigment properties, with optimized conditions yielding high-quality pigments. The comparison of synthetic methods demonstrates the trade-offs in terms of reaction complexity, particle size control, and yield, emphasizing the potential of hydrodynamic cavitation for efficient and scalable pigment production. The study concludes by summarizing the versatile reactions of FeSO4 and NaOH in producing various iron oxide and oxyhydroxide materials, which are valuable in industrial and environmental applications.

Drug-Induced Pigmentation: A Review.

Drug-induced pigmentation (DIP) is estimated to account for 20% of all cases of acquired hyperpigmentation. Over 50 agents have been implicated, including antibiotics, antimalarials, antiretrovirals, antipsychotics, prostaglandin analogs, heavy metals, and chemotherapeutic agents. The skin, mucosal surfaces, nails, and hair can all be affected, with the color, distribution, onset, and duration of pigmentation varying between offending agents. Both a thorough physical examination and medication history are necessary to determine the offending agent. In terms of mechanism, DIP occurs most frequently through the accumulation of melanin within the dermis but also by drug accumulation, pigment synthesis, and iron deposition. Photoprotection, including applying a broad-spectrum sunscreen, wearing photoprotective clothing, and seeking shade, plays an important role in the prevention of exacerbation of DIP. Multiple lasers, including the picosecond alexandrite, Q-switched Nd:YAG, Q-switched alexandrite, and Q-switched ruby lasers, have been successful in obtaining clearance of DIP. In this review, we examine the unique characteristics of each of the inciting agents in terms of incidence, clinical presentation, time to onset and resolution, and pathogenesis.

1, 3, 6, 8-pyrene sulfonic acid tetrasodium fluorescent pigment synthesis and security ink production

Colorants used in security inks are special pigments that radiate in the UV region or IR region. Obtained pigments can be from valuable rare earth elements or they can be organic based. Organic-based pigments are generally insoluble in water, which limits their use. For this purpose, an organic-based UV-radiating pigment was synthesized and made water-soluble by forming its salt. With the obtained salt-formed pigment, inkjet ink that can be used in counterfeiting was applied and its printability and resistance properties were determined. In this study, 1, 3, 6, 8-pyrene sulfonic acid tetrasodium salt was synthesized and water-based inkjet inks with hydroxy ethyl cellulose binder were produced. The prepared inks were printed on the paper surface. The color and gloss of the prints obtained were measured both in the visible region and in the UV region. Its optical properties were detected by UV spectroscopy. Strength properties such as light fastness, nitro resistance, alkali resistance, acid resistance, rub resistance, drying time, adhesion and dry film weight of the prints were determined. As a result; Inkjet ink with 1, 3, 6, 8-pyrene sulfonic acid tetrasodium salt was produced and it was concluded that it has good resistance properties.

The effects of polypropylene microplastics on the removal of nitrogen and phosphorus from water by Acorus calamus, Iris tectorum and functional microorganisms

Polypropylene microplastics (PP-MPs), an emerging pollutant, adversely affect the ability of aquatic plants to restore water bodies, thereby compromising the functionality and integrity of wetland ecosystems. This study examines the effects of microplastic stress on the nitrogen and phosphorus removal capacities of Acorus calamus and Iris tectorum, as well as on functional microorganisms within the aquatic system. The findings indicate that under PP-MP stress, the nitrogen and phosphorus absorption capabilities of both plants were diminished. Additionally, there was a significant reduction in the metabolic enzyme activities related to nitrogen and phosphorus in the plants, alongside a notable decrease in leaf nitrogen content. PP-MPs hinder the nutrient uptake of plants, affecting their growth and indirectly reducing their ability to utilize nitrogen and phosphorus. Specifically, in the 10 mg L−1 treatment group, A. calamus and I. tectorum showed reductions in leaf nitrogen content by 23.1% and 31.0%, respectively, and by 14.8% and 27.7% in the 200 mg L−1 treatment group. Furthermore, I. tectorum had higher leaf nitrogen levels than A. calamus. Using fluorescent tagging, the distribution of PP-MPs was traced in the roots, stems, and leaves of the plants, revealing significant growth impairment in both species. This included a considerable decline in photosynthetic pigment synthesis, enhanced oxidative stress responses, and increased lipid peroxidation in cell membranes. PP-MP exposure also significantly reduced the abundance of functional microorganisms involved in denitrification and phosphorus removal at the genus level in aquatic systems. Ecological function predictions revealed a notable decrease in nitrogen cycling functions such as nitrogen respiration and nitrite denitrification among water microorganisms in both treatment groups, with a higher ecological risk potential in the A. calamus treatment group. This study provides new insights into the potential stress mechanisms of PP-MPs on aquatic plants involved in water body remediation and their impacts on wetland ecosystems.

Chromophoric Keratin‐Cysteine Particle Synthesis Using Factorial Design of Experiment

The quest for novel chromophoric materials with tunable properties to match the natural spectrum of skin tones lacks comprehensive solutions, particularly in harnessing natural proteins for pigment synthesis. This research delved into the synthesis of sub‐micron Keratin‐Cysteine particles inspired by natural pigment production pathways. Adjustment of the initial conditions of the water‐based reaction between keratin, tyrosinase and cysteine, yielded Keratin‐Cysteine particles with colors tunable within the light to intermediate skin tone range. A systematic investigation of the reaction conditions through factorial design of experiment (DOE) identified the sequence of addition of tyrosinase and cysteine as the key determinant of color tone. Ultraviolet‐visible (UV‐Vis) spectroscopy, attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy and color analysis were performed to elucidate the reaction mechanism. This research presents a promising approach to chromophore synthesis for cosmetic and biomedical applications.

Conjunctive BSA-Seq and BSR-Seq to Map the Genes of Yellow Leaf Mutations in Hot Peppers (Capsicum annuum L.).

Yellow leaf mutations have been widely used to study the chloroplast structures, the pigment synthesis, the photosynthesis mechanisms and the chlorophyll biosynthesis pathways across various species. For this study, a spontaneous mutant with the yellow leaf color named 96-140YBM was employed to explore the primary genetic elements that lead to the variations in the leaf color of hot peppers. To identify the pathways and genes associated with yellow leaf phenotypes, we applied sequencing-based Bulked Segregant Analysis (BSA-Seq) combined with BSR-Seq. We identified 4167 differentially expressed genes (DEGs) in the mutant pool compared with the wild-type pool. The results indicated that DEGs were involved in zeatin biosynthesis, plant hormone signal transduction, signal transduction mechanisms, post-translational modification and protein turnover. A total of 437 candidates were identified by the BSA-Seq, while the BSR-Seq pinpointed four candidate regions in chromosomes 8 and 9, containing 222 candidate genes. Additionally, the combination of BSA-Seq and BSR-Seq showed that there were 113 overlapping candidate genes between the two methods, among which 8 common candidates have been previously reported to be related to the development of chloroplasts, the photomorphogenesis and chlorophyll formation of plant chloroplasts and chlorophyll biogenesis. qRT-PCR analysis of the 8 common candidates showed higher expression levels in the mutant pool compared with the wild-type pool. Among the overlapping candidates, the DEG analysis showed that the CaKAS2 and CaMPH2 genes were down-regulated in the mutant pool compared to the wild type, suggesting that these genes may be key contributors to the yellow leaf phenotype of 96-140YBM. This research will deepen our understanding of the genetic basis of leaf color formation and provide valuable information for the breeding of hot peppers with diverse leaf colors.

Transcriptome Analysis Revealed ZmPTOX1 Is Required for Seedling Development and Stress Tolerance in Maize.

Plant seedling morphogenesis is considerably related to photosynthesis, pigment synthesis, and circadian periodicity during seedling development. We identified and cloned a maize zebra or crossbanding leaves mutant wk3735, which produces pale white kernels and was identified and plays a role in the equilibrium of the Redox state the in/out of ETC by active oxygen scavenging. Interestingly, it produces the zebra leaves during the production of the first seven leaves, which is apparently different from the mutation of homologs AtPTOX in Arabidopsis. It is intriguing to investigate how and why yellow crossbands (zebra leaf phenotype) emerge on leaves. As expected, chlorophyll concentration and photosynthetic efficiency both significantly declined in the yellow sector of wk3735 leaves. Meanwhile, we observed the circadian expression pattern of ZmPTOX1, which was further validated by protein interaction assays of the circadian clock protein TIM1 and ZmPTOX1. The transcriptome data of yellow (muW) and green (muG) sectors of knock-out lines and normal leaves of overexpression lines (OE) at the 5th-leaf seedling stage were analyzed. Zebra leaf etiolated sections exhibit a marked defect in the expression of genes involved in the circadian rhythm and rhythmic stress (light and cold stress) responses than green sections. According to the analysis of co-DEGs of muW vs. OE and muG vs. OE, terms linked to cell repair function were upregulated while those linked to environmental adaptability and stress response were downregulated due to the mutation of ZmPTOX1. Further gene expression level analyses of reactive oxygen species (ROS) scavenging enzymes and detection of ROS deposition indicated that ZmPTOX1 played an essential role in plant stress resistance and ROS homeostasis. The pleiotropic roles of ZmPTOX1 in plant ROS homeostasis maintenance, stress response, and circadian rhythm character may collectively explain the phenotype of zebra leaves during wk3735 seedling development.

CuO Nanoparticles Reduce Toxicity and Enhance Bioaccumulation of Cadmium and Lead in the Cells of the Microalgae Desmodesmus communis.

The removal of pollutants, including heavy metals, from the aquatic environment is an urgent problem worldwide. Actively developing nanotechnology areas is becoming increasingly important for solving problems in the field of the remediation of aquatic ecosystems. In particular, methods for removing pollutants using nanoparticles (NPs) are proposed, which raises the question of the effect of a combination of NPs and heavy metals on living organisms. In this work, we investigated the role of CuO-NPs in changing the toxicity of Cd and Pb salts, as well as the bioaccumulation of these elements in a culture of the microalga Desmodesmus communis. It was found that CuO-NPs at concentrations of 10, 100, and 1000 µg L-1 had no effect on the viability of microalgae cells. On the 14th day of the experiment, Cd at a concentration of 1 mg L-1 reduced the viability index by 30% and, when combined with CuO-NPs, by 25%, i.e., CuO-NPs slightly reduced the toxic effect of Cd. At the same time, in this experiment, when CuO-NPs and Cd were used together, the level of oxidative stress increased, including on the first day in mixtures with 1 mg L-1 Cd. Under the influence of Pb, the cell viability index decreased by 70% by the end of the experiment, regardless of the metal concentration. The presence of CuO-NPs slightly reduced the toxicity of Pb in terms of viability and reactive oxygen species (ROS). At the same time, unlike Cd, Pb without NPs caused ROS production on the first day, whereas the addition of CuO-NPs completely detoxified Pb at the beginning and had a dose-dependent effect on mixtures at the end of the experiment. Also, the introduction of CuO-NPs slightly reduced the negative effect of Pb on pigment synthesis. As a molecular mechanism of the observed effects, we prioritized the provocation of oxidative stress by nanoparticles and related gene expression and biochemical reactions of algae cells. Analysis of the effect of CuO-NPs on the Cd and Pb content in microalgae cells showed increased accumulation of heavy metals. Thus, when algae were cultured in an environment with Cd and CuO-NPs, the Cd content per cell increased 4.2 times compared to the variant where cells were cultured only with Cd. In the case of Pb, the increase in its content per one cell increased 6.2 times when microalgae were cultured in an environment containing CuO-NPs. Thus, we found that CuO-NPs reduce the toxic effects of Cd and Pb, as well as significantly enhance the bioaccumulation of these toxic elements in the cells of D. communis microalgae. The results obtained can form the basis of technology for the nanobioremediation of aquatic ecosystems from heavy metals using microalgae.

The Impact of Growing Area on the Expression of Fruit Traits Related to Sensory Perception in Two Tomato Cultivars.

Environmental conditions greatly influence the quality of tomato fruit by affecting the expression of genes, the abundance of metabolites, and the perception of sensorial attributes. In this study, a fruit transcriptome investigation, a sensory test, and a metabolomic analysis were performed to evaluate the impact of the environment on two popular tomato cultivars grown in two Italian regions. The transcriptional profile of each cultivar, cultivated in two different areas, highlighted differential expression in genes involved in pathways related to cell wall components such as pectin, lignin, and hemicellulose and sugars as well as in amino acids, phenylpropanoids, and pigment synthesis. The cultivation area mainly affects sensory attributes related to texture and flavor and the metabolic pattern of cell wall precursors, sugars, glutamate, aspartate, and carotenoids. In the two genotypes cultivated in the same environment, some attributes and fruit-related quality processes are similarly affected, while others are differently influenced based on the specific genetic makeup of the tomato. A combination of transcriptomic, sensory, and metabolomic data obtained from the two tomato genotypes revealed that the environment has a profound effect on specific sensory traits, providing information on factors that shape the specific characteristics and genetic targets for improving tomato fruit characteristics.

Effect of different timing of water deficit combined with foliar application of ascorbic acid on physiological variables of sour passion fruit

The objective of this study was to evaluate the effects of deficit irrigation treatments during different phenological stages and foliar application of ascorbic acid on gas exchange, photosynthetic pigments, chlorophyll fluorescence, electrolyte leakage, relative water content and yield of ‘BRS GA1’ sour passion fruit. Treatments were distributed in randomized blocks, in a split-plot scheme, with plots consisting of six deficit irrigation treatments, based on crop evapotranspiration – ETc (irrigation with 100% ETc - FULL; irrigation with 50% ETc in the vegetative stage - VEG; flowering stage - FLO; fruiting stage - FRU; successively in the vegetative/flowering stages - VEG + FLO and vegetative/fruiting stages - VEG + FRU) and subplots represented by three concentrations of ascorbic acid - AsA (0, 0.5 and 1.0 mM). Water deficit induces changes in photosynthetic activity across all developmental stages of sour passion fruit, resulting in reduced yield in the period of 160 and 200 days after transplanting. Notably, flowering exhibits the greatest physiological acclimatization to water deficit conditions, albeit with more pronounced losses in the yield. When water deficit occurs during the vegetative and fruiting stages and is coupled with foliar application of ascorbic acid at 0.5 mM, there is an enhancement in the synthesis of photosynthetic pigments in ‘BRS GA1’ sour passion fruit. Overall, foliar application of ascorbic acid at concentrations of 0.5 and 1.0 mM emerges as a viable strategy to mitigate the adverse effects of water deficit on the physiology and yield of sour passion fruit at 200 days after transplanting.

Metabolome and transcriptome unveil the mechanism of light on regulating beauvericin synthesis in Cordyceps chanhua

Cordyceps chanhua, an important cordycipitoid medical mushroom with wide use in Asia, has gained attention for its bioactive component beauvericin (BEA), which is of medicinal value as a drug lead, but also of food safety risk. Recent observations by our group revealed a significant decrease of BEA content in C. chanhua when exposed to light, but the underlying regulatory mechanisms remain elusive. In this study, a comprehensive approach combining metabolomics and transcriptomics was employed to investigate the effects of white light on the secondary metabolism of C. chanhua for elucidation of the influence of light on BEA biosynthesis in this fungus. The result showed that the genes and metabolites involved in the synthesis of D-hydroxyisovaleric acid, a precursor of BEA synthesis, were down-regulated under light exposure, while those associated with the synthesis of phenylalanine, another precursor of BEA synthesis, were up-regulated leading to elevated phenylalanine levels. It suggested that the suppressive effect of light on BEA synthesis in C. chanhua occurred primarily through the inhibition of D-hydroxyisovaleric acid synthesis, while the enhanced phenylalanine biosynthesis likely directed towards other metabolic pathway such as pigment synthesis. These results contributed to a better understanding on how light modulates the secondary metabolism of C. chanhua and provided valuable guidance for optimizing BEA production in cultivation practices.

Optimization of Phycocyanobilin Synthesis in E. coli BL21: Biotechnological Insights and Challenges for Scalable Production.

Phycocyanobilin (PCB) is a small chromophore found in certain phycobiliproteins, such as phycocyanins (PCs) and allophycocyanins (APCs). PCB, along with other phycobilins (PBs) and intermediates such as biliverdin (BV) or phycoerythrobilin (PEB), is attracting increasing biotechnological interest due to its fluorescent and medicinal properties that allow potential applications in biomedicine and the food industry. This study aims to optimize PCB synthesis in Escherichia coli BL21 (DE3) and scale the process to a pre-industrial level. Parameters such as optimal temperature, inducer concentration, initial OD600, and stirring speed were analyzed in shake flask cultures to maximize PCB production. The best results were obtained at a temperature of 28 °C, an IPTG concentration of 0.1 mM, an initial OD600 of 0.5, and an orbital shaking speed of 260 rpm. Furthermore, the optimized protocol was scaled up into a 2 L bioreactor batch, achieving a maximum PCB concentration of 3.8 mg/L. Analysis of the results revealed that biosynthesis of exogenous PBs in Escherichia coli BL21 (DE3) is highly dependent on the metabolic burden of the host. Several scenarios, such as too rapid growth, high inducer concentration, or mechanical stress, can advance entry into the stationary phase. That progressively halts pigment synthesis, leading, in some cases, to its excretion into the growth media and ultimately triggering rapid degradation by the host. These conclusions provide a promising protocol for scalable PCB production and highlight the main biotechnological challenges to increase the yields of the process.

Study of Anti-Corosion Properties of Pigments Fe2O3-Al2O3-MgO Obtained by Coprecipitation

Promising pigments of the passivating type, in addition to phosphate ones, are other materials - oxyhydroxides, ferrites, molybdates, stanates, borates, tungstates, which are obtained using traditional technologies. condition. Researchers are becoming increasingly interested in the co-precipitation method, which makes it possible to vary the cationic and anionic composition of pigments and obtain nanodispersed products. In addition, developers of paints and varnishes are faced with the task of replacing toxic anti-corrosion chromium-, cadmium- and plumbum-containing pigments that are part of most modern inhibitory primers with pigments that are safe for human health. An alternative to such paint and varnish materials are oxide type fillers, which are anti-corrosion pigments, including oxyhydroxides, magnesium ferrites, cobalt aluminates, zinc ferrites, copper ferrites, magnesium aluminates, zinc aluminates, etc. The color of pigments and their anticorrosion properties depend on the chromophore ions included in the structure of the resulting compounds.Co-precipitation technology has a number of advantages over traditional ones and can radically reduce the cost of producing oxide materials. This process, based on the use of the internal chemical energy of the system, allows synthesis to be carried out at reduced temperatures, synthesis duration and energy costs. The simplicity of the equipment, the possibility of synthesizing a significant amount of the product of the desired phase and granulometric composition, and the environmental friendliness of the process also indicate the feasibility of using this method. Recently, attempts have been made to obtain pigments by co-precipitation, but no systematic studies have been carried out on the final products. The resulting products were in most cases poorly reproducible. In this regard, it becomes interesting to synthesize in a mode that would make it possible to obtain pigments with good color characteristics in a finely dispersed state, and eliminate the labor-intensive grinding stage, study the conditions for the formation of pigments with the structure of oxyhydroxides, the influence of their composition on color and anti-corrosion properties, study the patterns of formation of anti-corrosion properties, development of compositions for producing pigments using the co-precipitation method and subsequent heat treatment. Through experimental and theoretical studies, the influence of the nature of chromophore cations on the color tone, color purity, and anti-corrosion properties of pigments in the Fe-Al-Mg-O system has been established, which allows for the targeted synthesis of beige, red and yellow pigments with high anti-corrosion properties. The main technological properties of pigments are determined by the composition of metal-containing anions. The anti-corrosion properties of oxyhydroxide pigments are largely determined by the presence of hydroxide ions formed due to dissociation. The greatest effect is observed in the case of using metal compounds whose dissociation constants differ significantly. The protective effect is mainly determined by the slowdown of the anodic process. At the same time, anions containing aluminum atoms accelerate corrosion processes.

Physiological and Transcriptome Responses of Sweet Potato [Ipomoea batatas (L.) Lam] to Weak-Light Stress.

In the relay intercropping system of maize/sweet potato, the growth of the sweet potatoes is seriously limited by weak light stress in the early stage due to shade from maize plants. However, it is not clear how the weak light affects sweet potatoes and causes tuberous root loss. By setting two light intensity levels (weak light = 30% transmittance of normal light), this study evaluated the responses of two sweet potato cultivars with different tolerances to weak light in a field-based experiment and examined the divergence of gene expression related to light and photosynthesis in a pot-based experiment. The results showed that under weak light, the anatomic structure of functional leaves changed, and the leaf thickness decreased by 39.98% and 17.32% for Yuhongxinshu-4 and Wanshu-7, respectively. The ratio of S/R increased, and root length, root superficial area, and root volume all decreased. The photosynthetic enzyme rubisco was weakened, and the net photosynthetic rate (Pn) declined as well. The level of gene expression in Wanshu-7 was higher than that of Yuhongxinshu-4. The KEGG analysis showed that differentially expressed genes from the two cultivars under weak-light stress used the same enrichment pathway, mainly via glutathione metabolism and flavonoid biosynthesis. After full light levels were restored, the differentially expressed genes were all enriched in pathways such as photosynthesis, photosynthetic pigment synthesis, and carbon metabolism. These findings indicated that weak light changed the plant morphology, photosynthetic physiology and gene expression levels of sweet potatoes, which eventually caused losses in the tuberous root yield. The more light-sensitive cultivar (Wanshu-7) had stronger reactions to weak light. This study provides a theoretical basis and strategy for breeding low-light-tolerant varieties and improving relay intercropping production in sweet potatoes.

The Tet-on system for controllable gene expression in the rock-inhabiting black fungus Knufia petricola

Knufia petricola is a black fungus that colonizes sun-exposed surfaces as extreme and oligotrophic environments. As ecologically important heterotrophs and biofilm-formers on human-made surfaces, black fungi form one of the most resistant groups of biodeteriorating organisms. Due to its moderate growth rate in axenic culture and available protocols for its transformation and CRISPR/Cas9-mediated genome editing, K.petricola is used for studying the morpho-physiological adaptations shared by extremophilic and extremotolerant black fungi. In this study, the bacteria-derived tetracycline (TET)-dependent promoter (Tet-on) system was implemented to enable controllable gene expression in K. petricola. The functionality i.e., the dose-dependent inducibility of TET-regulated constructs was investigated by using GFP fluorescence, pigment synthesis (melanin and carotenoids) and restored uracil prototrophy as reporters. The newly generated cloning vectors containing the Tet-on construct, and the validated sites in the K. petricola genome for color-selectable or neutral insertion of expression constructs complete the reverse genetics toolbox. One or multiple genes can be expressed on demand from different genomic loci or from a single construct by using 2A self-cleaving peptides, e.g., for localizing proteins and protein complexes in the K.petricola cell or for using K. petricola as host for the expression of heterologous genes.

Production of nutritionally active compounds from Spirulina platensis under various stress conditions

The free-floating, filamentous cyanobacteria Spirulina platensis is highly valued and in great demand worldwide for its high-value colors and phytonutrients. These compounds find use in health foods, feed, medicines, and diagnostics. The primary objective of this work was to enhance the growth of Spirulina under both oxidative and physiological stress conditions in order to maximize the synthesis of phycocyanin and carotenoid pigments. Cultures were subjected to different concentrations of hydrogen peroxide (H2O2) and sodium chloride for varying temperatures and pH levels. Under lower concentrations of H2O2 (4mM), the maximum carotenoid content was increased, but the phycocyanin content was found to be stimulated at 10mM. Moreover, the synthesis of both pigments was shown to be highest under physiological stress circumstances (40mM and 60mM NaCl concentration) and at an optimal pH of 8-9, helped by a temperature range of 25-30℃. The experimental results demonstrate that both carotenoid and phycocyanin exhibit antioxidant properties even in the presence of oxidative stress. This suggests that the aforementioned circumstances can be applied in future investigations to extract different antioxidants from S. platensis.

Synthesis and Characterization of Red Pigment from Acid Regeneration Plant (ARP) By-product Via Rod Milling Process

Iron o xide waste from acid regeneration plants (ARP) is often discarded due to its non-profitability. This research aims to introduce a value-added process to convert iron oxide waste into red pigment via rod milling process. The iron oxide waste collected from ARP was grinded with a rod milling machine at 30 rpm for 24 hours. The ground product was then mixed with industrial-grade red pigment in various ratios. The mixed samples were then rod-milled again into ultra-fine particles. A total of seven samples were prepared, applied onto a canvas and analysed by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) methods. From the analyses, the existence, composition, and orientation of iron oxide were established. The waste-derived red pigments were subsequently subjected to particle size analysis on a scanning electron microscopy (SEM) platform, with results showcasing the efficiency of the rod milling process. Colour-related properties of the samples before and after canvas application were investigated using the L*a*b* system with a chromameter. Empirical outcomes indicated that the a* value plays an important role in determining the redness of the sample. Overall, the a* values obtained were above 15 and gradually increased in accordance to the amount of industrial-grade red pigment added. The oil absorptivity of red pigments was also tested via an oil absorptivity test. Notably, the assay signified that particle size and porosity affect the amount of oil that can be absorbed by the pigment.

Studies of the Morphology of Hematite Synthesized from Waste Iron Sulfate.

Microwave-based reactions have gained traction in recent years due to their ability to enhance reaction rates and yield while reducing energy consumption. Also, according to the conception of 'waste to materials', various waste feeds are intensively sought to be tested. The experimental setup of this study involved varying pH levels, oxidation agents, and precipitation agents to optimize the synthesis process of iron red based on waste iron sulfate. The selection of oxidation and precipitation agents was found to significantly influence the pigment synthesis process. Various oxidizing agents, including hydrogen peroxide and atmospheric air, were evaluated for their effectiveness in promoting the oxidation of ferrous ions to ferric ions, essential for pigment formation. Additionally, different precipitation agents such as sodium hydroxide and ammonia solution were assessed for their ability to precipitate iron hydroxides and facilitate pigment particle formation. The characterization of synthesized pigments revealed promising results in terms of quality and color properties. Helium Ion Microscopy (HIM) analysis confirmed the formation of well-defined pigment particles with controlled morphology. X-ray diffraction (XRD) studies provided insights into the crystalline structure of the pigments, indicating the presence of characteristic iron oxide phases. By improving this technology, waste iron sulfate can be efficiently transformed into valuable iron pigments, offering a sustainable solution for waste management while meeting the growing demand for high-quality pigments.

Recycling potato waste for the production of blue pigments by Streptomyces lydicus PM7 through submerged fermentation

BackgroundDiscarded potato is the most abundant potato waste and represents a worldwide disposal problem to the potato industry. This agricultural waste contains valuable nutrients that could be used as substrate to obtain diverse high value-added microbial products, such as biopigments. The aim of this work was to evaluate the use of discarded potato as a sole substrate source for producing blue pigments by Streptomyces lydicus PM7 through submerged fermentation.ResultsInitially, the traditional culture medium ISP2 was established as suitable for inoculum preparation, as it allowed high growth rates and consumption of ~ 75% reducing sugar, leading to 1.3 g L−1 dry biomass at 72 h of incubation. The formulated discarded potato broth (DPB) medium was evaluated together with five other traditional liquid culture media (potato dextrose broth, ISP2, ISP3, ISP4, and ISP5) for producing blue pigments by S. lydicus PM7. The highest blue pigment production was obtained by using DPB medium, reaching ~ 0.97 g L−1, followed by ISP5 (~ 0.36 g L−1). In terms of evaluating the concentration of discarded potato powder, the highest concentration of blue pigments was obtained with 16 g L−1, compared to concentrations of 4, 8, and 32 g L−1. In general, a notable increase in total proteins (~ 14 g L−1 in biomass; ~ 8 g L−1 in medium) and reducing sugars (~ 5 g L−1) on the fifth day of DPB fermentation was observed, at which time the production of blue pigments began. These data proved that S. lydicus PM7 is able to degrade potato wastes during submerged fermentation and to direct metabolism towards the formation of biopigments. Chromatographic analysis revealed that the main blue pigment produced by new strain in this complex medium is actinorhodin.ConclusionsDiscarded potato favored the production of blue pigments by S. lydicus PM7 under submerged fermentation, leading to final product concentration almost three times higher than others traditional Streptomyces culture media. To the best of our knowledge, this is the first report on the production of actinorhodin by the specie S. lydicus, as well as on this pigment synthesis based on an agricultural waste as a sole nutrient source for fermentation process. The findings showed that potato waste could be a potential byproduct for replacement of commercial culture media using for this same purpose.Graphical

Final piece to the Fusarium pigmentation puzzle – Unraveling of the phenalenone biosynthetic pathway responsible for perithecial pigmentation in the Fusarium solani species complex

The Fusarium solani species complex (FSSC) is comprised of important pathogens of plants and humans. A distinctive feature of FSSC species is perithecial pigmentation. While the dark perithecial pigments of other Fusarium species are derived from fusarubins synthesized by polyketide synthase 3 (PKS3), the perithecial pigments of FSSC are derived from an unknown metabolite synthesized by PKS35. Here, we confirm in FSSC species Fusarium vanettenii that PKS35 (fsnI) is required for perithecial pigment synthesis by deletion analysis and that fsnI is closely related to phnA from Penicillium herquei, as well as duxI from Talaromyces stipentatus, which produce prephenalenone as an early intermediate in herqueinone and duclauxin synthesis respectively. The production of prephenalenone by expression of fsnI in Saccharomyces cerevisiae indicates that it is also an early intermediate in perithecial pigment synthesis. We next identified a conserved cluster of 10 genes flanking fsnI in F. vanettenii that when expressed in F. graminearum led to the production of a novel corymbiferan lactone F as a likely end product of the phenalenone biosynthetic pathway in FSSC.