scholarly journals A Comparison of Constitutive and Inducible Non-Endogenous Keto-Carotenoids Biosynthesis in Synechocystis sp. PCC 6803

2019 ◽  
Vol 7 (11) ◽  
pp. 501 ◽  
Author(s):  
Menin ◽  
Lami ◽  
Musazzi ◽  
Petrova ◽  
Santabarbara ◽  
...  

The model cyanobacterium Synechocystis sp. PCC 6803 has gained significant attention as an alternative and sustainable source for biomass, biofuels and added-value compounds. The latter category includes keto-carotenoids, which are molecules largely employed in a wide spectrum of industrial applications in the food, feed, nutraceutical, cosmetic and pharmaceutical sectors. Keto-carotenoids are not naturally synthesized by Synechocystis, at least in any significant amounts, but their accumulation can be induced by metabolic engineering of the endogenous carotenoid biosynthetic pathway. In this study, the accumulation of the keto-carotenoids astaxanthin and canthaxanthin, resulting from the constitutive or temperature-inducible expression of the CrtW and CrtZ genes from Brevundimonas, is compared. The benefits and drawbacks of the two engineering approaches are discussed.

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Zhenyu Zhang ◽  
Pengfu Liu ◽  
Weike Su ◽  
Huawei Zhang ◽  
Wenqian Xu ◽  
...  

AbstractTrans-4-hydroxy-l-proline is an important amino acid that is widely used in medicinal and industrial applications, particularly as a valuable chiral building block for the organic synthesis of pharmaceuticals. Traditionally, trans-4-hydroxy-l-proline is produced by the acidic hydrolysis of collagen, but this process has serious drawbacks, such as low productivity, a complex process and heavy environmental pollution. Presently, trans-4-hydroxy-l-proline is mainly produced via fermentative production by microorganisms. Some recently published advances in metabolic engineering have been used to effectively construct microbial cell factories that have improved the trans-4-hydroxy-l-proline biosynthetic pathway. To probe the potential of microorganisms for trans-4-hydroxy-l-proline production, new strategies and tools must be proposed. In this review, we provide a comprehensive understanding of trans-4-hydroxy-l-proline, including its biosynthetic pathway, proline hydroxylases and production by metabolic engineering, with a focus on improving its production.


2020 ◽  
Vol 57 ◽  
pp. 129-139 ◽  
Author(s):  
Laura Furelos Brey ◽  
Artur J. Włodarczyk ◽  
Jens F. Bang Thøfner ◽  
Meike Burow ◽  
Christoph Crocoll ◽  
...  

2016 ◽  
Vol 33 ◽  
pp. 1-11 ◽  
Author(s):  
Artur Wlodarczyk ◽  
Thiyagarajan Gnanasekaran ◽  
Agnieszka Zygadlo Nielsen ◽  
Nodumo Nokolunga Zulu ◽  
Silas Busck Mellor ◽  
...  

2020 ◽  
Vol 86 (17) ◽  
Author(s):  
Shivangi Mishra ◽  
Parul Pandey ◽  
Ashutosh Prakash Dubey ◽  
Aafreen Zehra ◽  
Chandan Singh Chanotiya ◽  
...  

ABSTRACT Escherichia coli and Saccharomyces cerevisiae have been used extensively for heterologous production of a variety of secondary metabolites. Neither has an endogenous high-flux isoprenoid pathway, required for the production of terpenoids. Azospirillum brasilense, a nonphotosynthetic GRAS (generally recognized as safe) bacterium, produces carotenoids in the presence of light. The carotenoid production increases multifold upon inactivating a gene encoding an anti-sigma factor (ChrR1). We used this A. brasilense mutant (Car-1) as a host for the heterologous production of two high-value phytochemicals, geraniol and amorphadiene. Cloned genes (crtE1 and crtE2) of A. brasilense encoding native geranylgeranyl pyrophosphate synthases (GGPPS), when overexpressed and purified, did not produce geranyl pyrophosphate (GPP) in vitro. Therefore, we cloned codon-optimized copies of the Catharanthus roseus genes encoding GPP synthase (GPPS) and geraniol synthase (GES) to show the endogenous intermediates of the carotenoid biosynthetic pathway in the Car-1 strain were utilized for the heterologous production of geraniol in A. brasilense. Similarly, cloning and expression of a codon-optimized copy of the amorphadiene synthase (ads) gene from Artemisia annua also led to the heterologous production of amorphadiene in Car-1. Geraniol or amorphadiene content was estimated using gas chromatography-mass spectrometry (GC-MS) and GC. These results demonstrate that Car-1 is a promising host for metabolic engineering, as the naturally available endogenous pool of the intermediates of the carotenoid biosynthetic pathway of A. brasilense can be effectively utilized for the heterologous production of high-value phytochemicals. IMPORTANCE To date, the major host organisms used for the heterologous production of terpenoids, i.e., E. coli and S. cerevisiae, do not have high-flux isoprenoid pathways and involve tedious metabolic engineering to increase the precursor pool. Since carotenoid-producing bacteria carry endogenous high-flux isoprenoid pathways, we used a carotenoid-producing mutant of A. brasilense as a host to show its suitability for the heterologous production of geraniol and amorphadiene as a proof-of-concept. The advantages of using A. brasilense as a model system include (i) dispensability of carotenoids and (ii) the possibility of overproducing carotenoids through a single mutation to exploit high carbon flux for terpenoid production.


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