Light-Driven Biosynthesis of myo-Inositol Directly From CO2 in Synechocystis sp. PCC 6803

Abstract

myo-inositol (MI) is an essential growth factor, nutritional source, and important precursor for many derivatives like D-chiro-inositol. In this study, attempts were made to achieve the "green biosynthesis" of MI in a model photosynthetic cyanobacterium Synechocystis sp. PCC 6803. First, several genes encoding myo-inositol-1-phosphate synthases and myo-inositol-1-monophosphatase, catalyzing the first or the second step of MI synthesis, were introduced, respectively, into Synechocystis. The results showed that the engineered strain carrying myo-inositol-1-phosphate synthase gene from Saccharomyces cerevisiae was able to produce MI at 0.97 mg L −1. Second, the combined overexpression of genes related to the two catalyzing processes increased the production up to 1.42 mg L −1. Third, to redirect more cellular carbon flux into MI synthesis, an inducible small RNA regulatory tool, based on MicC-Hfq, was utilized to control the competing pathways of MI biosynthesis, resulting in MI production of ∼7.93 mg L −1. Finally, by optimizing the cultivation condition via supplying bicarbonate to enhance carbon fixation, a final MI production up to 12.72 mg L −1 was achieved, representing a ∼12-fold increase compared with the initial MI-producing strain. This study provides a light-driven green synthetic strategy for MI directly from CO 2 in cyanobacterial chassis and represents a renewable alternative that may deserve further optimization in the future.

MoS2 Nanosheets–Cyanobacteria Interaction: Reprogrammed Carbon and Nitrogen Metabolism

“…For example, ( r )-3- hydroxybutyric acid (3HB), a precursor to synthesize biodegradable plastics poly­(hydroxyalkanoates) (PHAs) and many related chemicals, was increased 2.5–6.9-fold upon exposure to MoS 2 nanosheets. Myo-inositol is a precursor for many valuable chemicals used in the functional food and pharmaceutical industry; the abundance of myo-inositol increased 20–38-fold upon exposure to MoS 2 nanosheets. In addition, d -myo-inositol-4-phosphate, the downstream product of myo-inositol, increased 603–1620-fold compared to unamended controls.…”

Harnessing the Endogenous 2μ Plasmid of Saccharomyces cerevisiae for Pathway Construction

“…Taking these results into account, in order to improve the stability of endogenous 2µ-based expression vector in yeast, an essential gene could be introduced into the plasmid while knocking out the same essential gene in the genome to ensure the existence of engineered endogenous 2µ plasmid in yeast (Zeng et al, 2021). In the future, researchers could apply the CRISPR/Cas9 system to directly integrate metabolic pathways into the endogenous 2µ plasmid with an essential gene in vivo (Dean-Johnson and Henry, 1989;Zheng et al, 1993;Wang et al, 2020;Yang et al, 2021). In summary, our endogenous 2µ-based expression vector p2µM has improved stability than the commonly used YEp pRS423, so it could be applied in S. cerevisiae for genetic manipulations.…”

Sustainable protein production through genetic engineering of cyanobacteria and use of atmospheric N2 gas

“…With the in‐depth analysis of the genome of cyanobacteria, the accumulation of knowledge of the metabolic network of cells, and the step‐by‐step application of metabolic engineering theories and methods, it is possible to utilize genetic engineering technologies to rationally design and selectively transform the metabolic pathways of cyanobacteria cells accumulate target products. Metabolic engineering is an extension of genetic engineering techniques, such as CRISPR/Cas technology and genome engineering, which have been successfully applied to cyanobacteria for metabolic and genetic modifications (Govindasamy et al., 2022; Wang, Chen, et al., 2020b; Wang, Gao, & Yang, 2020a). These techniques have shown promise in optimizing cyanobacterial cells for industrial production and have the potential to unlock their capabilities for sustainable biotechnologies.…”

“…However, large‐scale application of these techniques is still a technical challenge due to the low yields of bioproducts. Ongoing efforts are focused on characterizing and developing genetic regulatory parts and strategies to overcome these limitations (Wang, Chen, et al., 2020b; Wang, Gao, & Yang, 2020a). Overall, the application of genetic engineering techniques to cyanobacteria shows promise for the development of high‐throughput genome engineering and the optimization of cyanobacterial cells for various industrial applications, and the scope of cyanobacteria cell factories is constantly expanding.…”