An attractive example is the biodegradable polyester polybutylene succinate (PBS), which is derived from the polymerization of SA with 1,4-butanediol. Apart from its potential conversion to numerous valuable chemical compounds such as adipic acid, 1,4-butanediol, γ-butyrolactone, and tetrahydrofuran, SA can also be utilized as a monomer for the production of bio-based polyesters. Succinic acid (SA) is an organic acid which has been among the top 12 platform chemicals that can be obtained from carbohydrate biomass. The study illustrates that the theoretical CO 2-fixation capacity increases with increasing electron density of the co-substrate. The latter authors scrutinized the thermodynamic feasibility of such processes for different acids and different (co-) substrates. A popular example for such a mixed substrate utilization is the production of organic acids. However, CO 2 can also be directly used as a substrate in the production of chemicals by heterotrophic microbes provided that a reduced (and energy rich) co-substrate is used and that the target product is more oxidized than this co-substrate (when normalized to the number of carbon atoms). sugars, glycerol or lipids) originate from biomass generated by CO 2-fixing autotrophic organisms.
We indirectly use CO 2 in industrial biotechnology as soon as the feedstocks (e.g. The term ‘renewable’ concerns the direct or indirect use of present-day CO 2 instead of fossil resources. The use of renewable resources for the production of chemicals, fuels and materials by microbial cell factories is a central aspect of industrial biotechnology contributing to the vision of a circular economy. The achievements are encouraging to invest in future efforts establishing a process for SA production from (crude) glycerol and CO 2. The overexpression of PYC2 and the increased availability of bicarbonate, the co-substrate for the PYC reaction, further strengthened this capacity. The greatly increased capacity of the rTCA pathway obviously allowed successful competition with other pathways for the common precursor pyruvate. The data strongly suggest that a major part of dicarboxylic acids in our 2nd-generation SA-producer was formed via the rTCA pathway enabling a net fixation of CO 2. Off-gas analysis in controlled bioreactors with CO 2-enriched gas-phase indicated that CO 2 was fixed during the SA production phase. 0.1 Cmol Cmol −1 at the time point when SA yield was highest). Cultivation conditions which directly or indirectly increased the concentration of bicarbonate, led to an accumulation of malate in addition to the predominant product SA (ca. The data also suggest that the glyoxylate cycle did not contribute to the SA production in the new strain. The modifications in this 2nd-generation SA producer improved the maximum biomass-specific glycerol consumption rate by a factor of nearly four compared to the isogenic baseline strain solely equipped with the dihydroxyacetone (DHA) pathway for glycerol catabolism. Resultsīy changing the design of the expression cassettes for the rTCA pathway, overexpressing PYC2, and adding CaCO 3 to the batch fermentations, an SA yield on glycerol of 0.63 Cmol Cmol −1 was achieved (i.e. The current study aimed at improving the flux into the rTCA pathway accompanied by a higher CO 2-fixation and SA yield. The results of that previous study suggested that the glyoxylate cycle considerably contributed to SA accumulation in the respective strain. Recently, we described an engineered Saccharomyces cerevisiae strain which allowed SA production in synthetic glycerol medium with a maximum yield of 0.23 Cmol Cmol −1. Among reduced carbon sources, glycerol is particularly attractive since it allows a nearly twofold higher CO 2-fixation yield compared to sugars. The microbial production of succinic acid (SA) from renewable carbon sources via the reverse TCA (rTCA) pathway is a process potentially accompanied by net-fixation of carbon dioxide (CO 2).
0 kommentar(er)
