The suppression of torulene and torularhodin treatment on the growth of PC-3 xenograft prostate tumors

Research advancements in the maintenance mechanism of Sporidiobolus pararoseus enhancing the quality of soy sauce during fermentation

Soy sauce is a traditional condiment that undergoes microbial fermentation of various ingredients to achieve its desired color, scent, and flavor. Sporidiobolus pararoseus, which is a type of Rhodocerevisiae, shows promising potential as a source of lipids, carotenoids, and enzymes that can enrich the taste and color of soy sauce. However, there is currently a lack of systematic and comprehensive studies on the functions and mechanisms of action of S. pararoseus during soy sauce fermentation. In this review, it is well established that S. pararoseus produces lipids that are abundant in unsaturated fatty acids, particularly oleic acid, as well as various carotenoids, such as β-carotene, torulene, and torularhodin. These pigments are synthesized through the mevalonic acid pathway and possess remarkable antioxidant properties, acting as natural colorants. The synthesis of carotenoids is stimulated by high salt concentrations, which induces oxidative stress caused by NaCl. This stress further activates crucial enzymes involved in carotenoid production, ultimately leading to pigment formation. Moreover, S. pararoseus can produce high-quality enzymes that aid in the efficient utilization of soy sauce substrates during fermentation. Furthermore, this review focused on the impact of S. pararoseus on the color and quality of soy sauce and comprehensively analyzed its characteristics and ingredients. Thus, this review serves as a basis for screening high-quality oleaginous red yeast strains and improving the quality of industrial soy sauce production through the wide application of S. pararoseus.

A New Method for Selective Extraction of Torularhodin from Red Yeast Using CO2-SFE Technique

Torularhodin is a dark pink colored carotenoid belonging to the xanthophylls group that can be biologically synthesized by red yeasts, especially by Rhodotorula and Sporobolomyces genera. The growing interest in this molecule is due to its biological activities such as antioxidant, anticholesterolemic, anti-inflammatory, antimicrobial, and anticancer. To satisfy potential commercial markets, numerous methods have been proposed to develop a cost-effective and environmentally friendly downstream process for the purification of torularhodin. However, obtaining high purity products without resorting to the use of toxic solvents, which can leave residues in the final preparations, remains a major challenge. In this context, the present study aimed to develop a new efficient method for the isolation of torularhodin from the red yeast Rhodotorula strain ELP2022 by applying the extraction technique with supercritical CO2 (CO2-SFE) in two sequential steps. In particular, in the first step, the dried lysed biomass of yeast was subjected to the action of CO2 in supercritical conditions (CO2SC) as sole solvent for extraction of apolar carotenoids. In the second step, the residual biomass was subjected to the action of CO2SC using ethanol as a polar co-solvent for the extraction of torularhodin. Both steps were carried out at different operating parameters of temperature (40 and 60 °C) and pressure (from 300 to 500 bar) with a constant CO2 flow of 6 L min-1. Regardless of the operating conditions used, this method allowed to obtain an orange-colored oily extract and a red-colored extract after the first and second step, respectively. In all trials, torularhodin represented no less than 95.2% ± 0.70 of the total carotenoids in the red extracts obtained from the second step. In particular, the best results were obtained by performing both steps at 40 °C and 300 bar, and the maximum percentage of torularhodin achieved was 97.9% ± 0.88. Since there are no data on the selective recovery of torularhodin from red yeast using the SFE technique, this study may be a good starting point to optimize and support the development of industrial production of torularhodin by microbial synthesis. This new method can significantly reduce the environmental impact of torularhodin recovery and can be considered an innovation for which an Italian patent application has been filed. In a circular bioeconomy approach, this method will be validated up to a pilot scale, culturing the strain Rhodotorula spp. ELP2022 on low-cost media derived from agri-food wastes.

Multi-omics analysis reveals the mechanism of torularhodin accumulation in the mutant Rhodosporidium toruloides A1-15 under nitrogen-limited conditions

A carotenoid production strain Rhodosporidium toruloides NP11 and its mutant strain R. toruloides A1-15 were studied under chemostat nitrogen-limited cultivation. Multi-omics analysis (metabolomics, lipidomics and transcriptomics) was used to investigate the different mechanisms of torularhodin accumulation between NP11 and A1-15. The results showed that the carotenoid synthesis pathway was significantly enhanced in A1-15 compared to NP11 under nitrogen limitation, due to the significant increase of torularhodin. Under nitrogen-limited conditions, higher levels of β-oxidation were present in A1-15 compared to those in NP11, which provided sufficient precursors for carotenoid synthesis. In addition, ROS stress accelerated the intracellular transport of iron ions, promoted the expression of CRTI and CRTY genes, and reduced the transcript levels of FNTB1 and FNTB2 in the bypass pathway, and these factors may be responsible for the regulation of high torularhodin production in A1-15. This study provided insights into the selective production of torularhodin.

Microalgae, Seaweeds and Aquatic Bacteria, Archaea, and Yeasts: Sources of Carotenoids with Potential Antioxidant and Anti-Inflammatory Health-Promoting Actions in the Sustainability Era

Carotenoids are a large group of health-promoting compounds used in many industrial sectors, such as foods, feeds, pharmaceuticals, cosmetics, nutraceuticals, and colorants. Considering the global population growth and environmental challenges, it is essential to find new sustainable sources of carotenoids beyond those obtained from agriculture. This review focuses on the potential use of marine archaea, bacteria, algae, and yeast as biological factories of carotenoids. A wide variety of carotenoids, including novel ones, were identified in these organisms. The role of carotenoids in marine organisms and their potential health-promoting actions have also been discussed. Marine organisms have a great capacity to synthesize a wide variety of carotenoids, which can be obtained in a renewable manner without depleting natural resources. Thus, it is concluded that they represent a key sustainable source of carotenoids that could help Europe achieve its Green Deal and Recovery Plan. Additionally, the lack of standards, clinical studies, and toxicity analysis reduces the use of marine organisms as sources of traditional and novel carotenoids. Therefore, further research on the processing of marine organisms, the biosynthetic pathways, extraction procedures, and examination of their content is needed to increase carotenoid productivity, document their safety, and decrease costs for their industrial implementation.

Rhodotorula sp. as a cell factory for production of valuable biomolecules

Rhodotorula sp. are well-known for their ability to biosynthesize a diverse range of valuable biomolecules, including carotenoids, lipids, enzymes, and polysaccharides. Despite the high number of studies conducted using Rhodotorula sp. at the laboratory scale, most of these do not address all processual aspects necessary for scaling up these processes for industrial applications. This chapter explores the potential of Rhodotorula sp. as a cell factory for the production of distinct biomolecules, with a particular emphasis on exploring their use from a biorefinery perspective. Through in-depth discussions of the latest research and insights into non-conventional applications, we aim to provide a comprehensive understanding of Rhodotorula sp.'s ability to produce biofuels, bioplastics, pharmaceuticals, and other valuable biochemicals. This book chapter also examines the fundamentals and challenges associated with the optimizing upstream and downstream processing of Rhodotorula sp-based processes. We believe that through this chapter, readers with different levels of expertise will gain insights into strategies for enhancing the sustainability, efficiency, and effectiveness of producing biomolecules using Rhodotorula sp.

Anti-microbial, anti-oxidant, and anti-breast cancer properties unraveled in yeast carotenoids produced via cost-effective fermentation technique utilizing waste hydrolysate

Introduction

Natural carotenoids are well known for their anti-oxidant property and also shown to have antimicrobial and anticancer efficacy. Production of carotenoids from microbial resources mainly from yeast has attracted commercial interest. Breast cancer has the highest incidence among women, and therapy resistance and lack of effective therapeutic strategies are major treatment bottlenecks, particularly for triple-negative subtypes. Yeast carotenoids are recently being evaluated for affordable, non-toxic, natural product-based therapies. In the present study, we have shown an environment-friendly and inexpensive method for carotenoid production from yeasts, utilizing "mandi" wastes, and investigated the biomedical properties of carotenoids, particularly antineoplastic properties.

Methods

Vegetable "mandi" waste was used to prepare waste hydrolysate, a culture medium, in which oleaginous red yeast Rhodosporidium sp. was grown. Carotenoid pigments were extracted using the solvent extraction method and analyzed by UV spectroscopy, thin-layer chromatography (TLC), and high-performance liquid chromatography (HPLC). Antimicrobial, antioxidant, and anticancer activities of the extract were evaluated, followed by in silico docking and absorption, distribution, metabolism, and excretion/toxicity (ADME/T) studies.

Results

Carotenoid extract was found to be composed of three main pigments-β-carotene, torulene, and torularhodin. Extract exhibited significant antioxidant, antimicrobial, and anti-breast cancer activities in vitro while being biocompatible. Interestingly, carotenoids have shown better efficacy in triple-negative breast cancer (TNBC) cells than ER+PR+ cells. In silico evaluation predicted binding with breast cancer-specific molecular targets, specifically the three components showed good binding energy toward VEGF receptors and good drug likeliness properties, as well as less toxicity.

Discussion

This is the first report on anti-breast cancer activities, particularly targeting TNBC cells by red yeast carotenoids (β-carotene, torulene, and torularhodin) produced via a sustainable environment-friendly bioprocess utilizing waste hydrolysate.

Ascomycota as a source of natural colorants

In the last few decades, there has been a great demand for natural colorants. Synthetic colorants are known to be easy to produce, are less expensive, and remain stable when subjected to chemical and physical factors. In addition, only small amounts are required to color any material, and unwanted flavors and aromas are not incorporated into the product. Natural colorants present in food, in addition to providing color, also have biological properties and effects that aid in the prevention and cure of many diseases. The main classes of colorants produced by phylum Ascomycota include polyketides and carotenoids. A promising producer of colorants should be able to assimilate a variety of sources of carbon and nitrogen and also exhibit relative stability. The strain should not be pathogenic, and its product should not be toxic. Production processes should also provide the expected color with a good yield through simple extraction methods. Research that seeks new sources of these compounds should continue to seek products of biotechnological origin in order to be competitive with products of synthetic and plant origin. In this review, we will focus on the recent studies on the main producing species, classes, and metabolic pathways of colorants produced by this phylum, historical background, impact of synthetic colorants on human health and the environment, social demand for natural colorants and also an in-depth approach to bioprocesses (influences on production, optimization of bioprocess, extraction, and identification), and limitations and perspectives for the use of fungal-based dyes.

Microbial torularhodin – a comprehensive review

The demand for food, feed, cosmeceutical, and nutraceutical supplements/additives from natural sources has been rapidly increasing, with expectations for a faster expansion than the growth of the global markets in the coming years. In this framework, a particular interest is given to carotenoids due to their outstanding antioxidant activities, particularly the xanthophylls class. Torularhodin is one of these carotenoids that stands out for its multifunctional role as: antioxidant, anticancer and antimicrobial, yet its commercial potential is still unexplored. Although most xanthophylls can be naturally found in: microbial, plant and animal sources, torularhodin is only produced by microbial species, especially red oleaginous yeast. The microbial production of xanthophylls has many advantages as compared to other natural sources, such as: the need for low production area, easier extraction, high yields (at optimum operating conditions), and low (or no) seasonal, climatic, and geographic variation dependency. Due to the importance of natural products and their relevance to the market, this review provides a comprehensive overview of the: properties, characteristics and potential health benefits of torularhodin. Moreover, the most promising developments in both upstream and downstream processing to obtain this colorant from microbial sources are considered. For this purpose, the main microorganisms used for torularhodin production are firstly reviewed, including biosynthesis pathway and torularhodin properties. Following, an overall analysis of the processing aspects related with its: extraction, separation and purification is provided. Lastly, current status and future trends of torularhodin-based processes and products such as therapeutic agents or biomaterials are discussed, indicating promising directions toward biorefinery and circular economy.

Effect of Selected Cations and B Vitamins on the Biosynthesis of Carotenoids by Rhodotorula mucilaginosa Yeast in the Media with Agro-Industrial Wastes

In recent years, there has been an increase in the search for novel raw materials for the production of natural carotenoids. Among yeasts, Rhodotorula species have the ability to synthesize carotenoids, mainly β-carotene, torulene, and torularhodin, depending on the culture conditions. This study aimed to determine the effect of selected cations (barium, zinc, aluminum, manganese) and B vitamins (biotin, riboflavin, niacin, pantothenic acid) on the biosynthesis of carotenoids by Rhodotorula mucilaginosa MK1 and estimate the percentages of β-carotene, torulene, and torularhodin synthesized by the yeast. The cultivation was carried out in a medium containing glycerol (waste resulting from biodiesel production) as a carbon source and potato wastewater (waste resulting from potato starch production) as a nitrogen source. Carotenoid biosynthesis was stimulated by the addition of aluminum (300 mg/L) or aluminum (300 mg/L) and niacin (100 µg/L) to the medium. The number of carotenoids produced by R. mucilaginosa MK1 in the medium containing only aluminum and in the medium with aluminum and niacin was 146.7 and 180.5 µg/gd.m., respectively. This content was 101% and 147% higher compared to the content of carotenoids produced by yeast grown in the control medium (73.0 µg/gd.m.). The addition of aluminum and barium seemed to have a positive effect on the biosynthesis of torulene, and the percentage of this compound increased from 31.86% to 75.20% and 68.24%, respectively. Niacin supplementation to the medium increased the percentage of torularhodin produced by the yeast from 23.31% to 31.59–33.79%. The conducted study showed that there is a possibility of intensifying carotenoid biosynthesis by red yeast and changing the percentages of individual carotenoids fractions by adding cations or B vitamins to the medium. Further research is needed to explain the mechanism of action of niacin on the stimulation of torularhodin biosynthesis.

High-Quality Genome Assembly of Oleaginous Red Yeast Sporobolomyces roseus CGMCC 2.4355

Sporobolomyces roseus is an important oleaginous red yeast with critical biotechnological applications and has received significant recognition as a valuable source of industrial enzymes, carotenoids, and lipids. To reveal the genetic basis and functional components underlying its biotechnological applications, a high-quality genome assembly is required. Here, we present a novel genome assembly of S. roseus CGMCC 2.4355 using a combination of Illunima and Oxford Nanopore technologies. The genome has an assembly size of 21.4 Mb and consists of 15 scaffolds with an N50 length of 2,126,566 bp and GC content of 49.52%. The assembly is of high integrity, comprising 95.2% complete Benchmarking Universal Single-Copy Orthologs (BUSCOs) as evaluated by a genome completeness assessment. The genome was predicted to contain 8,124 protein-coding genes, 6,890 of which were functionally annotated. We believe that the combination of our analyses and high-quality genome assembly will promote the basic development of S. roseus as an agent for biotechnological applications and make a significant contribution to assess the evolutionary relationship of Sporobolomyces species.

Transcriptomic and Metabolomic Analyses Provide Insights into the Enhancement of Torulene and Torularhodin Production in Rhodotorula glutinis ZHK under Moderate Salt Conditions

Carotenoids are a group of tetraterpene pigments widely used in the food, pharmaceutical, and cosmetic industries. Torulene, torularhodin, and β-carotene, three principal carotenoids synthesized by Rhodotorula glutinis ZHK, possess strong health-promoting properties such as antioxidant, provitamin A, and antitumor. Here, the effect of different salt conditions on carotenoids production of R. glutinisZHK was investigated. The results showed that the total carotenoids were significantly enhanced in 0.5 M (3.91 mg/L) and 0.75 M (5.41 mg/L) NaCl treatments than that in 1.0 M (0.35 mg/L) and control (1.42 mg/L) after 120 h of cultivation. Of which, the increase in torulene and torularhodin production acts as the main contributor to the enhancement of total carotenoids. Transcriptome profiling revealed that salt stress efficiently promotes the gene expression of crtI, which could explain the molecular mechanisms of the enhanced torulene and torularhodin production under salt stress. Further experiments indicated that torulene and torularhodin play an important role in quenching excrescent reactive oxygen species induced by salt stress. Together, the present study reports an effective strategy for simultaneously improving torulene and torularhodin production in R. glutinis ZHK.

Recent Progress in Discovering the Role of Carotenoids and Their Metabolites in Prostatic Physiology and Pathology with a Focus on Prostate Cancer-A Review-Part I: Molecular Mechanisms of Carotenoid Action

Among the vast variety of plant-derived phytochemicals, the group of carotenoids has continuously been investigated in order to optimize their potential application in the area of dietary intervention and medicine. One organ which has been especially targeted in many of these studies and clinical trials is the human prostate. Without doubt, carotenoids (and their endogenous derivatives—retinoids and other apo-carotenoids) are involved in intra- and intercellular signaling, cell growth and differentiation of prostate tissue. Due to the accumulation of new data on the role of different carotenoids such as lycopene (LC) and β-carotene (BC) in prostatic physiology and pathology, the present review aims to cover the past ten years of research in this area. Data from experimental studies are presented in the first part of the review, while epidemiological studies are disclosed and discussed in the second part. The objective of this compilation is to emphasize the present state of knowledge regarding the most potent molecular targets of carotenoids and their main metabolites, as well as to propose promising carotenoid agents for the prevention and treatment of prostatic diseases.

Recent Progress in Discovering the Role of Carotenoids and Metabolites in Prostatic Physiology and Pathology-A Review-Part II: Carotenoids in the Human Studies

Among the vast variety of plant-derived phytochemicals, the group of carotenoids has continuously been investigated in order to optimize their potential application in the area of dietary intervention related to chronic diseases. One organ that has been especially targeted in many of these studies and clinical trials is the human prostate. Without doubt, carotenoids (and their endogenous derivatives-retinoids and apo-carotenoids) are involved in a plethora of intra- and intercellular signaling, cell growth, and differentiation of prostate tissue. Due to the accumulation of new data on the role of different carotenoids, such as lycopene (LYC) and β-carotene (BC), in prostatic physiology and pathology, the present review aimed to cover the past ten years of research in this regard. Data from experimental studies are presented in the first part of the review, while epidemiological studies are disclosed in this second part. The objective of this compilation was to emphasize the present state of knowledge about the most potent molecular targets of carotenoids, as well as to propose promising carotenoid agents for the prevention and possible treatment of prostatic diseases.

Carotenoids and Some Other Pigments from Fungi and Yeasts

Carotenoids are an essential group of compounds that may be obtained by microbiological synthesis. They are instrumental in various areas of industry, medicine, agriculture, and ecology. The increase of carotenoids' demand at the global market is now essential. At the moment, the production of natural carotenoids is more expensive than obtaining their synthetic forms, but several new approaches/directions on how to decrease this difference were developed during the last decades. This review briefly describes the information accumulated until now about the beneficial effects of carotenoids on human health protection, their possible application in the treatments of various diseases, and their use in the food and feed industry. This review also describes some issues that are linked with biotechnological production of fungal and yeasts carotenoids, as well as new approaches/directions to make their biotechnological production more efficient.

Genomics and lipidomics analysis of the biotechnologically important oleaginous red yeast Rhodotorula glutinis ZHK provides new insights into its lipid and carotenoid metabolism

Background

Rhodotorula glutinis is recognized as a biotechnologically important oleaginous red yeast, which synthesizes numerous meritorious compounds with wide industrial usages. One of the most notable properties of R. glutinis is the formation of intracellular lipid droplets full of carotenoids. However, the basic genomic features that underlie the biosynthesis of these valuable compounds in R. glutinis have not been fully documented. To reveal the biotechnological potential of R. glutinis, the genomics and lipidomics analysis was performed through the Next-Generation Sequencing and HPLC-MS-based metabolomics technologies.

Results

Here, we firstly assemble the genome of R. glutinis ZHK into 21.8 Mb, containing 30 scaffolds and 6774 predicted genes with a N50 length of 14, 66,672 bp and GC content of 67.8%. Genome completeness assessment (BUSCO alignment: 95.3%) indicated the genome assembly with a high-quality features. According to the functional annotation of the genome, we predicted several key genes involved in lipids and carotenoids metabolism as well as certain industrial enzymes biosynthesis. Comparative genomics results suggested that most of orthologous genes have underwent the strong purifying selection within the five Rhodotorula species, especially genes responsible for carotenoids biosynthesis. Furthermore, a total of 982 lipids were identified using the lipidomics approaches, mainly including triacylglycerols, diacylglyceryltrimethylhomo-ser and phosphatidylethanolamine.

Conclusion

Using whole genome shotgun sequencing, we comprehensively analyzed the genome of R. glutinis and predicted several key genes involved in lipids and carotenoids metabolism. By performing comparative genomic analysis, we show that most of the ortholog genes have undergone strong purifying selection within the five Rhodotorula species. Furthermore, we identified 982 lipid species using lipidomic approaches. These results provided valuable resources to further advance biotechnological applications of R .glutinis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-020-07244-z.

Metabolomics integrated with transcriptomics: assessing the central metabolism of marine red yeast Sporobolomyces pararoseus under salinity stress

Salinity stress is one of the most serious environmental issues in agricultural regions worldwide. Excess salinity inhibits root growth of various crops, and results in reductions of yield. It is of crucial to understand the molecular mechanisms mediating salinity stress responses for enhancing crops' salt tolerance. Marine red yeast Sporobolomyces pararoseus should have evolved some unique salt-tolerant mechanism, because they long-term live in high-salt ecosystems. However, little research has conducted so far by considering S. pararoseus as model microorganisms to study salt-tolerant mechanisms. Here, we successfully integrated metabolomics with transcriptomic profiles of S. pararoseus in response to salinity stress. Screening of metabolite features with untargeted metabolic profiling, we characterized 4862 compounds from the LC-MS/MS-based datasets. The integrated results showed that amino acid metabolism, carbohydrate metabolism, and lipid metabolism is significantly enriched in response to salt stress. Co-expression network analysis showed that 28 genes and 8 metabolites play an important role in the response of S. pararoseus, which provides valuable clues for subsequent validation. Together, the results provide valuable information for assessing the central metabolism of mediating salt responses in S. pararoseus and offer inventories of target genes for salt tolerance improvement via genetic engineering.

Xylose Metabolism and the Effect of Oxidative Stress on Lipid and Carotenoid Production in Rhodotorula toruloides: Insights for Future Biorefinery

The use of cell factories to convert sugars from lignocellulosic biomass into chemicals in which oleochemicals and food additives, such as carotenoids, is essential for the shift toward sustainable processes. Rhodotorula toruloides is a yeast that naturally metabolises a wide range of substrates, including lignocellulosic hydrolysates, and converts them into lipids and carotenoids. In this study, xylose, the main component of hemicellulose, was used as the sole substrate for R. toruloides, and a detailed physiology characterisation combined with absolute proteomics and genome-scale metabolic models was carried out to understand the regulation of lipid and carotenoid production. To improve these productions, oxidative stress was induced by hydrogen peroxide and light irradiation and further enhanced by adaptive laboratory evolution. Based on the online measurements of growth and CO2 excretion, three distinct growth phases were identified during batch cultivations. Majority of the intracellular flux estimations showed similar trends with the measured protein levels and demonstrated improved NADPH regeneration, phosphoketolase activity and reduced β-oxidation, correlating with increasing lipid yields. Light irradiation resulted in 70% higher carotenoid and 40% higher lipid content compared to the optimal growth conditions. The presence of hydrogen peroxide did not affect the carotenoid production but culminated in the highest lipid content of 0.65 g/gDCW. The adapted strain showed improved fitness and 2.3-fold higher carotenoid content than the parental strain. This work presents a holistic view of xylose conversion into microbial oil and carotenoids by R. toruloides, in a process toward renewable and cost-effective production of these molecules.

Carotenoids and lipid production from Rhodosporidium toruloides cultured in tea waste hydrolysate

BACKGROUND

In this study, renewable tea waste hydrolysate was used as a sole carbon source for carotenoids and lipid production. A novel Rhodosporidium toruloides mutant strain, RM18, was isolated through atmospheric and room-temperature plasma mutagenesis and continuous domestication in tea waste hydrolysate from R. toruloides ACCC20341.

RESULTS

RM18 produced a larger biomass and more carotenoids and α-linolenic acid compared with the control strain cultured in tea waste hydrolysate. The highest yields of torularhodin (481.92 μg/g DCW) and torulene (501 μg/g DCW) from RM18 cultured in tea waste hydrolysate were 12.86- and 1.5-fold higher, respectively, than that of the control strain. In addition, α-linolenic acid production from RM18 in TWH accounted for 5.5% of total lipids, which was 1.58 times more than that of the control strain. Transcriptomic profiling indicated that enhanced central metabolism and terpene biosynthesis led to improved carotenoids production, whereas aromatic amino acid synthesis and DNA damage checkpoint and sensing were probably relevant to tea waste hydrolysate tolerance.

CONCLUSION

Tea waste is suitable for the hydrolysis of microbial cell culture mediums. The R. toruloides mutant RM18 showed considerable carotenoids and lipid production cultured in tea waste hydrolysate, which makes it viable for industrial applications.

Evaluation of pulsed electric fields technology for the improvement of subsequent carotenoid extraction from dried Rhodotorula glutinis yeast

This research aims to evaluate whether the electroporation of Rhodotorula glutinis fresh biomass improved the subsequent extraction of carotenoids from dry biomass using supercritical CO2 and traditional solvent extraction. Supercritical CO2 extraction yields were low after all treatments assayed. Similarly, solvent extraction of carotenoids from untreated or PEF treated cells that were immediately freeze-dried after the pre-treatment was neither effective (extraction yield < 20% total content). Conversely, PEF-treatment and subsequent intermediate incubation in aqueous buffer for 24 h, followed by freeze-drying and extraction, led to a large improvement with the three solvents assayed (acetone, hexane, ethanol). Ethanol was the most efficient, reaching an extraction yield of 80% of total carotenoid, which represents a recovery of 267 µg/gdw. Torularhodin esters constituted the main carotenoid found in the extracts. This is of great interest, as ethanol is eco-friendly solvent and potential applications of torularhodin range from food to medical purposes.

C/N ratio and carbon source-dependent lipid production profiling in Rhodotorula toruloides

Microbial oils are lipids produced by oleaginous microorganisms, which can be used as a potential feedstock for oleochemical production. The oleaginous yeast Rhodotorula toruloides can co-produce microbial oils and high-value compounds from low-cost substrates, such as xylose and acetic acid (from hemicellulosic hydrolysates) and raw glycerol (a byproduct of biodiesel production). One step towards economic viability is identifying the best conditions for lipid production, primarily the most suitable carbon-to-nitrogen ratio (C/N). Here, we aimed to identify the best conditions and cultivation mode for lipid production by R. toruloides using various low-cost substrates and a range of C/N ratios (60, 80, 100, and 120). Turbidostat mode was used to achieve a steady state at the maximal specific growth rate and to avoid continuously changing environmental conditions (i.e., C/N ratio) that inherently occur in batch mode. Regardless of the carbon source, higher C/N ratios increased lipid yields (up to 60% on xylose at a C/N of 120) but decreased the specific growth rate. Growth on glycerol resulted in the highest specific growth and lipid production (0.085 g lipids/gDW*h) rates at C/Ns between 60 and 100. We went on to study lipid production using glycerol in both batch and fed-batch modes, which resulted in lower specific lipid production rates compared with turbisdostat, however, fed batch is superior in terms of biomass production and lipid titers. By combining the data we obtained in these experiments with a genome-scale metabolic model of R. toruloides, we identified targets for improvements in lipid production that could be carried out either by metabolic engineering or process optimization.

Pulsed electric field-assisted extraction of valuable compounds from microorganisms

Microorganisms (bacteria, yeast, and microalgae) are a promising resource for products of high value such as nutrients, pigments, and enzymes. The majority of these compounds of interest remain inside the cell, thus making it necessary to extract and purify them before use. This review presents the challenges and opportunities in the production of these compounds, the microbial structure and the location of target compounds in the cells, the different procedures proposed for improving extraction of these compounds, and pulsed electric field (PEF)-assisted extraction as alternative to these procedures. PEF is a nonthermal technology that produces a precise action on the cytoplasmic membrane improving the selective release of intracellular compounds while avoiding undesirable consequences of heating on the characteristics and purity of the extracts. PEF pretreatment with low energetic requirements allows for high extraction yields. However, PEF parameters should be tailored to each microbial cell, according to their structure, size, and other factors affecting efficiency. Furthermore, the recent discovery of the triggering effect of enzymatic activity during cell incubation after electroporation opens up the possibility of new implementations of PEF for the recovery of compounds that are bounded or assembled in structures. Similarly, PEF parameters and suspension storage conditions need to be optimized to reach the desired effect. PEF can be applied in continuous flow and is adaptable to industrial equipment, making it feasible for scale-up to large processing capacities.

Determination of the effects of torularhodin against alcoholic liver diseases by transcriptome analysis

Alcoholic liver disease (ALD) is a major cause of liver injury worldwide. Oxidative damage is one of the main injuries caused by ALD. The aim of this study was to elucidate the preventive effects of torularhodin, extracted from Sporidiobolus pararoseus, on alcoholic liver injury in mice. The mechanisms involved were investigated using transcriptome analysis. Torularhodin supplementation decreased ethanol-induced aspartate transaminase (ALT), aspartate transaminase (AST) and low density lipoprotein (LDL) levels, and increased high density lipoprotein (HDL) levels in the serum of mice. In liver tissue, treatment with torularhodin increased ethanol-induced superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels and decreased tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) levels. Histological analysis showed that torularhodin could alleviate the negative effects of alcohol on the liver. Transcriptomic analysis showed that 806 genes were significantly differentially expressed (506 up-regulated and 300 down-regulated) after torularhodin treatment. These genes were involved in three main Gene Ontology categories (biological process, cellular component, and molecular function) and multiple pathways. Therefore, torularhodin was considered to have potential as a protective agent against ALD.

Torularhodin Ameliorates Oxidative Activity in Vitro and d-Galactose-Induced Liver Injury via the Nrf2/HO-1 Signaling Pathway in Vivo

Torularhodin is a natural product extracted from Sporidiobolus pararoseus and has a similar chemical structure to β-carotene. The antioxidative effects of torularhodin were investigated using DPPH, ABTS, a cell oxidative damage model in vitro, and a d-galactose-induced liver-injured mouse model in vivo. Cell experiments demonstrated that torularhodin had a powerful effect on oxidative damage caused by H₂O₂ to AML12 cells. Torularhodin significantly reduced inflammatory cytokines and increased the activity of antioxidant enzymes both in mouse serum and the liver. The inhibition of d-galactose-induced oxidative damage in the liver was correlated with the torularhodin-mediated effects on improving the activity of Nrf2/HO-1, reducing the expression of Bax and NF-κB p65 by western blot analysis. RT-PCR results demonstrated torularhodin upregulated the antioxidative mRNA expression of Nrf2, NQO1, and HO-1 in the liver. In summary, torularhodin significantly scavenged free radicals and prevented oxidative damage in vitro and reduced d-galactose-induced liver oxidation via promotion of the Nrf2/HO-1 pathways in vivo.

Increased torulene production by the red yeast, Sporidiobolus pararoseus, using citrus juice

Response surface methodology was applied to maximize the yield and production of carotenoids by Sporidiobolus pararoseus WZ012 using citrus juice. A high concentration of yeast extract and citrus juice favored carotenoid production and biomass concentration, respectively. Under optimal conditions, a more than 51 percent (from 860 to 1300 µg/g) and 62 percent (from 17.05 to 27.66 mg/L) respective enhancement in intracellular and total carotenoid production was achieved. Finally, this process was successfully upscaled in a 5-L fermentor. A comparison of the carotenoid distributions revealed that torulene (61.3%) was the dominant carotenoid when using the citrus based medium, while the main carotenoid was β-carotene (62.5%) when using the glucose medium. The present work provides an alternative method to produce high-value products derived from waste and low-grade citrus.

Determination of the Molecular Mechanism of Torularhodin against Hepatic Oxidative Damage by Transcriptome Analysis

Torularhodin, extracted from Sporidiobolus pararoseus, is a significant carotenoid that is similar to lycopene in structure. Some studies have indicated torularhodin as having antioxidative activities. However, it has not been thoroughly studied with respect to its antioxidative activity and molecular mechanisms in liver injury. Therefore, the aim of this study was to elucidate the antioxidative activity of torularhodin against hydrogen peroxide- (H₂O₂-) induced damage and the mechanism involved through transcriptome analysis and to explore its antioxidant potential. BRL cells were first subjected to H₂O₂ damage and then treated with torularhodin. The results showed that at 10⁻⁵ g/ml, torularhodin had significant protective effects against H₂O₂-induced oxidative damage. Morphological and immunofluorescence staining showed that torularhodin could maintain cell integrity and enhance the activity of antioxidant enzymes in the cells. According to transcriptome analysis, 2808 genes were significantly differentially expressed (1334 upregulated and 1474 downregulated) after torularhodin treatment. These genes were involved in three major Gene Ontology categories (biological process, cellular component, and molecular function). Moreover, torularhodin was involved in some cellular pathways, such as cancer inhibition, antioxidation, and aging delay. Our data highlighted the importance of multiple pathways in the antioxidative damage of liver treated with torularhodin and will contribute to get the molecular mechanisms of torularhodin inhibition of hepatic oxidative damage.

Salt stress increases carotenoid production of Sporidiobolus pararoseus NGR via torulene biosynthetic pathway

Carotenoids represent a diverse class of aliphatic C40 molecules with a variety of applications in the food and pharmaceutical industries. Sporidiobolus pararoseus NGR produces various carotenoids, including torulene, torularhodin and β-carotene. Salt stress significantly increases the torulene accumulation of S. pararoseus NGR. However, little is known, about the molecular mechanisms underlying the increased torulene biosynthesis. In this work, we investigated the effects of NaCl treatment on the contents of carotenoids (both qualitatively and quantitatively) and transcriptome. A total of 12.3 Gb of clean bases were generated in six cDNA libraries. These bases were de novo assembled into 9,533 unigenes with an average length of 1,654 nt and N50 of 2,371 nt. Transcriptome analysis revealed that of 3,849 differential expressed genes (DEGs) in response to salt stress, 2,019 were up-regulated, and 1,830 were down-regulated. Among these DEGs, we identified three carotenogenic genes crtE, crtYB, and crtI. In addition, fourteen candidate genes were predicted to participate in the conversion from torulene to torularhodin. Our findings should provide insights into the mechanisms of carotenoid biosynthesis and salt-tolerance of S. pararoseus NGR.

Development of an Improved Carotenoid Extraction Method to Characterize the Carotenoid Composition under Oxidative Stress and Cold Temperature in the Rock Inhabiting Fungus Knufia petricola A95

Black yeasts are a highly specified group of fungi, which are characterized by a high resistance against stress factors. There are several factors enabling the cells to survive harsh environmental conditions. One aspect is the pigmentation, the melanin black yeasts often display a highly diverse carotenoid spectrum. Determination and characterization of carotenoids depend on an efficient extraction and separation, especially for black yeast, which is characterized by thick cell walls. Therefore, specific protocols are needed to ensure reliable analyses regarding stress responses in these fungi. Here we present both. First, we present a method to extract and analyze carotenoids and secondly we present the unusual carotenoid composition of the black yeast Knufia petricola A95. Mechanical treatment combined with an acetonitrile extraction gave us very good extraction rates with a high reproducibility. The presented extraction and elution protocol separates the main carotenoids (7) in K. petricola A95 and can be extended for the detection of additional carotenoids in other species. K. petricola A95 displays an unusual carotenoid composition, with mainly didehydrolycopene, torulene, and lycopene. The pigment composition varied in dependency to oxidative stress but remained relatively constant if the cells were cultivated under low temperature. Future experiments have to be carried out to determine if didehydrolycopene functions as a protective agent itself or if it serves as a precursor for antioxidative pigments like torulene and torularhodin, which could be produced after induction under stress conditions. Black yeasts are a promising source for carotenoid production and other substances. To unravel the potential of these fungi, new methods and studies are needed. The established protocol allows the determination of carotenoid composition in black yeasts.

Ameliorating effects of Sporidiobolus pararoseus extract on dyslipidemia in mice with high fat diet induced obesity

The study investigated how an extract of Sporidiobolus pararoseus (S.p.) affects lipid metabolism in Kunming mice that were obese as a result of being fed a high-fat diet; the control group were administered Max EPA fish oil. Ten mice were randomly selected from a pool of 60 mice for the control group and the remaining 50 mice were fed with a high-fat diet to establish a dyslipidemia model. After 4 weeks, these 50 mice were randomly distributed among 5 groups: high-fat model group; Max EPA group; and 3 groups of mice fed different doses of S.p. extract (low dose, medium dose, and high dose). After 8 weeks, the mice were sacrificed and the relevant parameters were measured. Compared with the high-fat model group, the group administered the high dose of S.p. extract showed significantly decreased body mass and serum levels of total cholesterol, triglycerides, and low-density lipoprotein cholesterol, and increased levels of high-density lipoprotein cholesterol. The results from RT-PCR showed that the mRNA expression of sterol regulatory element-binding protein 1c, fatty acid synthesis enzyme, and acetyl-CoA carboxylase was lower in the groups supplemented with S.p. extract than in the high-fat model group, whereas the expression of carnitine palmitoyltransferase 1 was higher in the group supplemented with S.p. extract than in the high-fat model group. Our results suggest that taking S.p. extract could benefit patients with dyslipidemia. Therefore, S.p. extract should be developed as a dietary supplement to improve lipid metabolism in obese people.

Torulene and torularhodin: "new" fungal carotenoids for industry?

Torulene and torularhodin represent the group of carotenoids and are synthesized by yeasts and fungi. The most important producers of these two compounds include yeasts of Rhodotorula and Sporobolomyces genera. The first reports confirming the presence of torulene and torularhodin in the cells of microorganisms date to the 1930s and 1940s; however, only in the past few years, the number of works describing the properties of these compounds increased. These compounds have strong anti-oxidative and anti-microbial properties, and thus may be successfully used as food, feedstock, and cosmetics additives. In addition, tests performed on rats and mice showed that both torulene and torularhodin have anti-cancerous properties. In order to commercialize the production of these two carotenoids, it is necessary to obtain highly efficient yeast strains, for example, via mutagenization and optimization of cultivation conditions. Further studies on the activity of torulene and torularhodin on the human body are also needed.

Torulene and torularhodin, protects human prostate stromal cells from hydrogen peroxide-induced oxidative stress damage through the regulation of Bcl-2/Bax mediated apoptosis

The current study was designed to elucidate the cytoprotective effects and possible mechanisms of torulene and torularhodin on hydrogen peroxide (H₂O₂)-induced oxidative stress damage in human prostate stromal cells (WPMY-1). After treated with H₂O₂, a notable decrease was appeared in cell viability, yet the decrease was attenuated when cells were pretreated with torulene and torularhodin (0.5-10 μM) as evaluated by WST-1 assay. Pretreatment with these two carotenoids significantly attenuated H₂O₂-induced apoptosis in WPMY-1 cells through the inhibition of intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) overproduction, as well as the activation of the activities in catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px). Finally, pretreatment of cells with carotenoids resulted in the regulation of the mRNA and protein expression of Bcl-2 and Bax in H₂O₂-exposed prostate stromal cells. The present results indicate that both torulene and torularhodin can protect human prostate stromal cells from oxidative stress damage via Bcl-2/Bax mediated apoptosis.

Rhodotorula glutinis-potential source of lipids, carotenoids, and enzymes for use in industries

Rhodotorula glutinis is capable of synthesizing numerous valuable compounds with a wide industrial usage. Biomass of this yeast constitutes sources of microbiological oils, and the whole pool of fatty acids is dominated by oleic, linoleic, and palmitic acid. Due to its composition, the lipids may be useful as a source for the production of the so-called third-generation biodiesel. These yeasts are also capable of synthesizing carotenoids such as β-carotene, torulene, and torularhodin. Due to their health-promoting characteristics, carotenoids are commonly used in the cosmetic, pharmaceutical, and food industries. They are also used as additives in fodders for livestock, fish, and crustaceans. A significant characteristic of R. glutinis is its capability to produce numerous enzymes, in particular, phenylalanine ammonia lyase (PAL). This enzyme is used in the food industry in the production of l-phenylalanine that constitutes the substrate for the synthesis of aspartame—a sweetener commonly used in the food industry.