scholarly journals Effectively Improve the Astaxanthin Production by Combined Additives Regulating Different Metabolic Nodes in Phaffia rhodozyma

Author(s):  
Zhipeng Li ◽  
Haoyi Yang ◽  
Chenhua Zheng ◽  
Xiping Du ◽  
Hui Ni ◽  
...  

Astaxanthin is an important natural resource that is widely found in marine environments. Metabolic regulation is an effective method for improving astaxanthin production in Phaffia rhodozyma. Most studies have focused on single regulators, which have limited effects. In this study, 16 metabolic regulators were screened to improve astaxanthin production in high-yield and wild-type strains. Fluconazol and glutamic acid increased astaxanthin volumetric yield in MVP14 by 25.8 and 30.9%, respectively, while ethanol increased astaxanthin volumetric yield in DSM626, 29.3%. Furthermore, six additives that inhibit the competing pathways and promote the main pathway for astaxanthin synthesis were selected for combination treatment. We found that the optimal combination was penicillin, ethanol, triclosan, and fluconazol, which increased astaxanthin cell yield by 51%. Therefore, we suggest that simultaneously promoting the master pathways (mevalonate) and inhibiting competing pathways (fatty acid synthesis and ergosterol) is the best strategy to improve astaxanthin cell yield. Moreover, regulators of the biomass pathway should be avoided to improve cell yield. This study provides a technical basis for the utilisation of astaxanthin in P. rhodozyma.

2019 ◽  
Author(s):  
Zhipeng Li ◽  
Lina Chen ◽  
Tianli Li ◽  
Xiping Du ◽  
Ning He ◽  
...  

Abstract Background Phaffia rhodozyma is a potential industrial source for production of natural astaxanthin. The synthetic mechanism of astaxanthin in P. rhodozyma is complex and unclear that blocked its development. Results In this study, eight genes related to dicyclic and monocyclic pathway in three different strains of P. rhodozyma were analyzed, and the relationship between the expression and astaxanthin biosynthesis was explored. Among these genes, crtYB (R=0.75, P<0.05) and asy genes (R=0.74, P<0.05) showed the most closely correlation with astaxanthin biosynthesis. In order to further study exact relationship, crtYB and asy genes were knocked out by homologous recombination. After crtYB knock-out, astaxanthin was decreased to be under detected line. It suggested crtYB played a role in dicyclic and monocyclic pathway. Meanwhile, the asy gene was in dicyclic pathway of astaxanthin biosynthesis, and its knock-out would promote the astaxanthin biosynthesis in monocyclic pathway, resulting in a 25.04% increase in astaxanthin production. Conclusion The possible rate-limiting enzymes were asy gene and crtYB illustrated by analysis of regression. Knock-out of asy and crtYB gene was great helpful to understand the synthetic pathway of astaxanthin, and significant to the industrial application of producing astaxanthin.


2020 ◽  
Author(s):  
Ziyuan Wang ◽  
Fengzhu Guo ◽  
Tianyu Dong ◽  
Zhilei Tan ◽  
Mohamed Abdelraof ◽  
...  

Abstract ε-polylysine (ε-PL) is a polypeptide that shows broad-spectrum inhibition against both Gram-positive and Gram-negative bacteria, and it’s mainly produced by Streptomyces sp. However, the biosynthesis mechanism of ε-PL by Streptomyces sp. is still unclear. Herein, the metabolomic analysis of the biosynthesis mechanism of ε-PL in the original strain TUST and the high-yield mutant strain 6#-7 were investigated. Results show that the difference on metabolisms between TUST and 6#-7 was significant during fermentation periods. And based on further analyses of the results of both metabolomics and enzymatic activity, a possible metabolic regulation mechanism of the high-yield mutagenized strain 6#-7 was proposed. The transport and absorption capacity for glucose of strain 6#-7 is improved. And the activity of enzymes relating to ε-PL synthesis, including Hexokinase (HK) et al., is strengthened. On the contrary, the activity of enzymes in the branched-chain pathways, such as Succinate dehydrogenase (SDH) et al. is decreased. Meanwhile, the increase of trehalose, glutamic acid and proline makes the strain 6#-7 more resistant to ε-PL. Moreover, the strain 6#-7 has stronger ability to transfer ε-PL out the cell. Thus the ability of the mutagenized strain to synthesize ε-PL is enhanced and the strain 6#-7 can produce more ε-PL compared with the original strain. These findings provide a theoretical basis for further improving the production of ε-PL.


2016 ◽  
Vol 7 (1) ◽  
pp. 63 ◽  
Author(s):  
BibhuPrasad Panda ◽  
Hina Nangia ◽  
Mojeer Hasan ◽  
Mohd. Azhar ◽  
PrakashChandra Bhatt

2016 ◽  
Vol 28 (2) ◽  
pp. 174
Author(s):  
M. A. Roberts ◽  
L. F. Campos-Chillon ◽  
M. Barceló-Fimbres ◽  
J. L. Altermatt

Current bovine embryo culture methods result in accumulation of lipids and reactive oxygen species, possibly due to sub-optimal metabolic regulation. These effects decrease the cryopreservation survival and implantation potential of in vitro-produced (IVP) embryos. Forskolin has been shown to decrease lipid accumulation, and vitamin K2 (Vit K2) is thought to decrease oxidative stress from in vitro conditions. The aims of this study were (1) to assess lipid content of embryos cultured with or without forskolin and Vit K2 in both continuous and sequential SOF-based medium, and (2) to examine individual and combined effects of forskolin and Vit K2 on mitochondrial polarity. For Experiment 1, a 2 × 2 × 2 factorial design was used to compare culture systems (continuous v. 3-step sequential), additives (no additive v. Vit K2 (0.5 mM at Day 3) plus forskolin (10 µM at Day 5), and blastocyst stage [6 (early) v. 7 (late)] on overall lipid content. For Experiment 2, mitochondrial polarity of stage 7 blastocysts was analysed from the following groups: no additive, Vit K2 (0.5 mM at Day 3), forskolin (10 µM at Day 5), and Vit K2 plus forskolin. IVP embryos (n = 199, Experiment 1; n = 45, Experiment 2) were produced by standard procedures and cultured at 38.5°C in 5% O2, 5% CO2, and 90% N2. For Experiment 1, embryos were stained with 1 μg mL–1 Nile Red, and two images per embryo were taken along the equatorial plane at 40× magnification. For Experiment 2, embryos were stained with 300 nM MitoTracker Red CMX-Rosamine, and 10 images per embryo were acquired by confocal microscopy with a 5-μm step size at 40× magnification. For both experiments, fluorescence intensity (FI) of each image was measured by Image PRO software with embryo controlled for and background fluorescence corrected. Data (Table 1) were analysed by ANOVA and means were compared by Tukey’s HSD. In Experiment 1, embryos cultured with forskolin and Vit K2 showed decreased lipid content in both the early and late stage (P < 0.05), with no effect from culture system (P > 0.05). In Experiment 2, forskolin and Vit K2 individually increased mitochondrial polarity (P < 0.05), but had no combined effect (P > 0.05). In conclusion, these data suggest that while a combination of forskolin and Vit K2 as media additives reduces lipid accumulation, the interaction between these metabolic regulators may negate their individual effects on mitochondrial polarity. Table 1.Fluorescence intensity of Nile Red and MitoTracker Red dyes between treatment groups


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