Genetic modification of Mucor circinelloides for canthaxanthin production by heterologous expression of β-carotene ketolase gene

11 pags, 4 figs, 1 tab. -- he Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fnut.2021.756218/full#supplementary-materiaCanthaxanthin is a reddish-orange xanthophyll with strong antioxidant activity and higher bioavailability than carotenes, primarily used in food, cosmetics, aquaculture, and pharmaceutical industries. The spiking market for natural canthaxanthin promoted researchers toward genetic engineering of heterologous hosts for canthaxanthin production. Mucor circinelloides is a dimorphic fungus that produces β-carotene as the major carotenoid and is considered as a model organism for carotenogenic studies. In this study, canthaxanthin-producing M. circinelloides strain was developed by integrating the codon-optimized β-carotene ketolase gene (bkt) of the Haematococcus pluvialis into the genome of the fungus under the control of strong promoter zrt1. First, a basic plasmid was constructed to disrupt crgA gene, a negative regulator of carotene biosynthesis resulted in substantial β-carotene production, which served as the building block for canthaxanthin by further enzymatic reaction of the ketolase enzyme. The genetically engineered strain produced a significant amount (576 ± 28 μg/g) of canthaxanthin, which is the highest amount reported in Mucor to date. Moreover, the cell dry weight of the recombinant strain was also determined, producing up to more than 9.0 g/L, after 96 h. The mRNA expression level of bkt in the overexpressing strain was analyzed by RT-qPCR, which increased by 5.3-, 4.1-, and 3-folds at 24, 48, and 72 h, respectively, compared with the control strain. The canthaxanthin-producing M. circinelloides strain obtained in this study provided a basis for further improving the biotechnological production of canthaxanthin and suggested a useful approach for the construction of more valuable carotenoids, such as astaxanthin.This work was supported by the National Natural Science Foundation of China (Grant Nos. 31670064 and 31972851), the Tai Shan Industrial Experts Program tscy 20160101, and the Shandong provincial key technology R&D plan (2018GNC110039, 2018GSF121013).Peer reviewe

Microbes as Biofertilizers, a Potential Approach for Sustainable Crop Production

Continuous decline of earth’s natural resources and increased use of hazardous chemical fertilizers pose a great concern for the future of agriculture. Biofertilizers are a promising alternative to hazardous chemical fertilizers and are gaining importance for attaining sustainable agriculture. Biofertilizers play a key role in increasing crop yield and maintaining long-term soil fertility, which is essential for meeting global food demand. Microbes can interact with the crop plants and enhance their immunity, growth, and development. Nitrogen, phosphorous, potassium, zinc, and silica are the essential nutrients required for the proper growth of crops, but these nutrients are naturally present in insolubilized or complex forms. Certain microorganisms render them soluble and make them available to the plants. The potential microbes, their mode of action, along with their effect on crops, are discussed in this review. Biofertilizers, being cost effective, non-toxic, and eco-friendly, serve as a good substitute for expensive and harmful chemical fertilizers. The knowledge gained from this review can help us to understand the importance of microbes in agriculture and the ways to formulate these microbes as biofertilizers for sustainable crop production

Microbes as Biofertilizers, a Potential Approach for Sustainable Crop Production

Continuous decline of earth’s natural resources and increased use of hazardous chemical fertilizers pose a great concern for the future of agriculture. Biofertilizers are a promising alternative to hazardous chemical fertilizers and are gaining importance for attaining sustainable agriculture. Biofertilizers play a key role in increasing crop yield and maintaining long-term soil fertility, which is essential for meeting global food demand. Microbes can interact with the crop plants and enhance their immunity, growth, and development. Nitrogen, phosphorous, potassium, zinc, and silica are the essential nutrients required for the proper growth of crops, but these nutrients are naturally present in insolubilized or complex forms. Certain microorganisms render them soluble and make them available to the plants. The potential microbes, their mode of action, along with their effect on crops, are discussed in this review. Biofertilizers, being cost effective, non-toxic, and eco-friendly, serve as a good substitute for expensive and harmful chemical fertilizers. The knowledge gained from this review can help us to understand the importance of microbes in agriculture and the ways to formulate these microbes as biofertilizers for sustainable crop production

Role of Education in Promoting Employment Opportunities in district Rajanpur (South Punjab) Pakistan

This study is based to examine the role of education in promoting employment opportunities in Rajanpur District (Southern Punjab) Pakistan. Study was descriptive in nature and survey method was assumed for the collection of data. The group of 200, teachers 170 and 30 lawyers were recognized as sample for this study purpose. Data was collected through questionnaire that was consisted 30 close ended questions and 3 open ended questions. Data was analyzed by using SPSS data analysis sheet, mean score, standard deviation, frequency, percentage, ANOVA, Tukeys HSD, Pearson correlation and simple linear regression.  Findings were drawn on the basis of data analysis and it showed that education had a positive relationship in employment opportunities. Results showed that it’s an important requirement for employment. Education is the key of employability and there is coordination between education and employability. Level of education is influencing the employability and lack of university education effecting on individual career. There is a connection between studies and workplace and policies in education to support unemployed youth to get work. There is involvement of private sector in educational institutions and education is influencing the career of individuals. Moreover, education is playing a positive role in employment opportunities

Effects of sesame seed extract as a natural antioxidant on the oxidative stability of sunflower oil

Natural and de-novo biosynthesized phyto-compounds have gained much significance because of their non-controversial nutritional, health and safety benefits as compared with chemically synthesized commercially rivalry antioxidants. However, none of natural de-novo biosynthesized phyto-compounds has been commercially available and used in customary food business and processing. In this study, efficacy of sesame seed extracts (SSEs) in stabilizing sunflower oil during storage has been studied. Fine powder of sesame seed was extracted in different solvents. The results showed that significant differences in extractability of different solvents and maximum extraction yield (29.48%) were achieved with methanol. The antioxidant components and capability of different extracts were further investigated and evaluated via total phenolic contents, DPPH radical scavenging activity and β-carotene/linoleic acid calorimetric assays respectively. Being highest in yield and antioxidant potential, methanolic extract was used; three different concentrations of SSE (500, 750, and 1000\ua0μL) were added in 100\ua0mL of sunflower oil to further evaluate its oxidative stability. Sensory and oxidative analysis of baked product from these groups was also evaluated

Microencapsulation of microbial antioxidants from Mucor circinelloides, their physico-chemical characterization, in vitro digestion and releasing behaviors in food

This study aimed at increasing the stability of heat-labile and pH-sensitive microbial antioxidants by the microencapsulation. Microbial antioxidants from Mucor circinelloides were microencapsulated. The physico-chemical and powder flowing properties of resulting microcapsules were evaluated. The initial safety studies were evaluated by in vivo acute oral toxicity tests. The bio-accessibility of powders vs. extracts was analyzed in in vitro digestion models with further application of microcapsules to model food system. Physico-chemical properties were significantly different (p 0.05) in powder flowing properties. The microencapsulation of extract with 5% whey protein hydrogels (WPHG) + 5% pectin (T) showed higher retain-ability of polyphenols accompanying low degradation in gastric and intestinal digestion and with no major toxicity signs. The addition of T microcapsule did not produce any nutritional, physico-chemical, compositional, and nutritional distinctions in cheese. Microencapsulation proved to be appropriate approach for not only protecting the thermo-labile and pH-sensitive microbial antioxidants but also for enhanced bioavailability, and targeted release of bioactive extracts

Comparative Study on the Role of Berberine and <i>Berberis lycium</i> Royle Roots Extract against the Biochemical Markers and Cyclin D1 Expression in HCC Animal Model

Diethylamine nitrosamine (DEN), as an initiator of liver tumor, and carbon tetrachloride (CCl4), as a tumor promoter, have been used to study the molecular events of liver cancer in animal models. Recently, our in vitro study reported BLE (Berberis lycium Royle ethanol extract) as the most effective agent against liver cancer, thus we continued our study in vivo to assess the hepatoprotective effect of BLE and its most active alkaloid, berberine, in albino mice (70 male). Moreover, we investigated the biochemical/immunohistochemical effects of a single alkaloid versus the effect of Berberis extract in mice liver. Hepatic cancer was induced in mice by a single intraperitoneal injection with DEN (100 mg/kg b.wt), followed by biweekly injections of CCl4 (0.5 mL/kg) for 30 days. The development of liver cancer was assessed after 60 days of DEN injection by measuring the elevated level of the serum tumor marker alpha-fetoprotein (AFP) and liver function test (ALT, AST, ALP, and BUN) markers. After the confirmation of liver cancer development, the BLE extract and berberine were fed to mice for 90 days and the serum biomarkers for liver injury (LFTs and AFP) were measured again. Overall, berberine (120 mg/kg b.wt) proved to be a stronger agent in reducing the symptoms of HCC in mice, as compared with BLE. Histopathological analysis agreed well with the biochemical observations. Immunohistochemistry analysis suggested significant suppression of the quantitative expression of the key oncogene cyclin D1 at low (60 mg/kg) and high (120 mg/kg) doses of berberine. These findings implicate the amelioration of hepatocarcinoma by berberine more prominently in mice, by suppression of cyclin-dependent kinase activator (CD1) expression, reducing LFTs, as well as AFP, in the serum. Thus, our findings are novel, as berberine may help in controlling the perturbation in CD1 associated with aggressive forms of HCC. However, future studies should be directed at finding out whether berberine has any effect on inhibitors (p27 and CDKI) of cyclin-dependent kinase too

In Vitro Anticancer Potential of Berberis lycium Royle Extracts against Human Hepatocarcinoma (HepG2) Cells

Human liver cancer has emerged as a serious health concern in the world, associated with poorly available therapies. The Berberis genus contains vital medicinal plants with miraculous healing properties and a wide range of bioactivities. In this study, different crude extracts of B. lycium Royle were prepared and screened against Human Hepatocarcinoma (HepG2) cell lines. The water/ethanolic extract of B. lycium Royle (BLE) exhibited significant antiproliferative activity against the HepG2 cancer cell line with an IC50 value of 47 μg/mL. The extract decreased the clonogenic potential of HepG2 cells in a dose-dependent manner. It induced apoptotic cell death in HepG2 cells that were confirmed by cytometric analysis and microscopic examination of cellular morphology through DAPI-stained cells. Biochemical evidence of apoptosis came from elevating the intracellular ROS level that was accompanied by the loss of mitochondrial membrane potential. The mechanism of apoptosis was further confirmed by gene expression analysis using RT-qPCR that revealed the decline in Bcl-2 independent of p53 mRNA and a rise in CDK1 while downregulating CDK5, CDK9, and CDK10 mRNA levels at 48 h of BLE treatment. The most active fraction was subjected to HPLC which indicated the presence of berberine (48 μg/mL) and benzoic acid (15.8 μg/mL) as major compounds in BLE and a trace amount of luteolin, rutin, and gallic acid. Our study highlighted the importance of the most active BLE extract as an excellent source of nutraceuticals against Human Hepatocarcinoma that can serve as an herbal natural cure against liver cancer

Role of Cytosolic Malic Enzyme in Oleaginicity of High-Lipid-Producing Fungal Strain Mucor circinelloides WJ11

Mucor circinelloides, an oleaginous filamentous fungus, is gaining popularity due to its ability to synthesize significant amounts of lipids containing &gamma;-linolenic acid (GLA) that have important health benefits. Malic enzyme (ME), which serves as the main source of NADPH in some fungi, has been found to regulate lipid accumulation in oleaginous fungi. In the present study, the role of two cytosolic ME genes, cmalA and cmalB, in the lipid accumulation of the M. circinelloides high-lipid-producing strain WJ11, was evaluated. Strains overexpressing cmalA and cmalB showed a 9.8- and 6.4-fold rise in specific ME activity, respectively, and an elevation of the lipid content by 23.2% and 5.8%, respectively, suggesting that these genes are involved in lipid biosynthesis. Due to increased lipid accumulation, overall GLA content in biomass was observed to be elevated by 11.42% and 16.85% in cmalA and cmalB overexpressing strains, respectively. Our study gives an important insight into different studies exploring the role of the cmalA gene, while we have for the first time investigated the role of the cmalB gene in the M. circinelloides WJ11 strain

Different Classes of Phytohormones Act Synergistically to Enhance the Growth, Lipid and DHA Biosynthetic Capacity of Aurantiochytrium sp. SW1

In the present study, the impact of eight phytohormones from six different classes on the growth, lipid and docosahexaenoic acid (DHA) biosynthetic capacity of Aurantiochytrium sp. SW1 (SW1) was evaluated. Kinetin (KIN), jasmonic acid (JA) and gibberellic acid (GA) significantly enhanced the growth and DHA production of SW1 by 16%&ndash;28% and 66%&ndash;84% in comparison to the control, respectively. The synergistic effect of these three phytohormones, evaluated by the response surface methodology (RSM), showed that a combination of 3.6 mg/L GA, 2.0 mg/L KIN and 20.0 mg/L JA further increased the growth and DHA production of SW1 by 16% to 28% and 22% to 36%, respectively, in comparison to the individual supplementation. The synergistic effect of these phytohormones was also shown to be time-dependent, where feeding at 24 h of cultivation led to 15%, 26% and 35% further increments in the biomass, lipid and DHA production in comparison to that of 0 h, respectively. The determination of stress markers, antioxidant enzymes and key enzymes involved in fatty acid biosynthesis aided to elucidate the potential mechanism underlying the improvement of growth and DHA production by SW1 at various times of feeding. Supplementation with the phytohormones at 24 h exhibited the maximum impact on reducing the level of reactive oxygen species (ROS) and malondialdehyde (MDA), as well as augmented the antioxidants (superoxide dismutase and catalase) and key metabolic enzymes involved in lipogenesis (malic, glucose-6-phosphate dehydrogenase and ATP-citrate lyase) in comparison to the control and other time points. This study signifies the potential application of phytohormones for improving the growth, lipid and DHA production in Aurantiochytrium spp