Improved polyhydroxybutyrate production by Saccharomyces cerevisiae through the use of the phosphoketolase pathway

Abstract

The metabolic pathways of the central carbon metabolism in Saccharomyces cerevisiae are well studied and consequently S. cerevisiae has been widely evaluated as a cell factory for many industrial biological products. In this study, we investigated the effect of engineering the supply of precursor, acetyl-CoA, and cofactor, NADPH, on the biosynthesis of the bacterial biopolymer polyhydroxybutyrate (PHB), in S. cerevisiae. Supply of acetyl-CoA was engineered by over-expression of genes from the ethanol degradation pathway or by heterologous expression of the phophoketolase pathway from Aspergillus nidulans. Both strategies improved the production of PHB. Integration of gapN encoding NADP(+) -dependent glyceraldehyde-3-phosphate dehydrogenase from Streptococcus mutans into the genome enabled an increased supply of NADPH resulting in a decrease in glycerol production and increased production of PHB. The strategy that resulted in the highest PHB production after 100 h was with a strain harboring the phosphoketolase pathway to supply acetyl-CoA without the need of increased NADPH production by gapN integration. The results from this study imply that during the exponential growth on glucose, the biosynthesis of PHB in S. cerevisiae is likely to be limited by the supply of NADPH whereas supply of acetyl-CoA as precursor plays a more important role in the improvement of PHB production during growth on ethanol.

Recent advances in biosynthesis of fatty acids derived products in Saccharomyces cerevisiae via enhanced supply of precursor metabolites

“…3) were introduced to boost the availability of acetyl-CoA in yeast [34,67]. Notably, improved production of amorphadiene [59], α-santalene [6], PHB [33,34], n-butanol [36,43], 3-HP [75], and fatty acids [67] were achieved by engineering the acetyl-CoA pool in S. cerevisiae. Considering the significance of acetyl-CoA in cellular metabolism, nature has evolved various routes to synthesize acetyl-CoA under different conditions.…”

“…To overcome such limitations, a feedback inhibition insensitive ACS mutant from Salmonella enterica (SeAcs L641P ) [6,33,36,59] and/or alternative acetyl-CoA biosynthetic pathways with less energy input requirement (Fig. 3) were introduced to boost the availability of acetyl-CoA in yeast [34,67]. Notably, improved production of amorphadiene [59], α-santalene [6], PHB [33,34], n-butanol [36,43], 3-HP [75], and fatty acids [67] were achieved by engineering the acetyl-CoA pool in S. cerevisiae.…”

Enhancing pentose phosphate pathway in Corynebacterium glutamicum to improve l‐isoleucine production

“…1). Overexpression of G6PDH, 6PGDH, or PGL could enhance the production of poly-hydroxybutyrate [16], xylitol [17], hydrogen [18], riboflavin [19], and l-lysine [20]. Fructose 1,6-bisphosphatase (FBPase) encoded by fbp is part of the gluconeogenetic pathway and essential for C. glutamicum to grow on noncarbohydrates such as acetate.…”

EngineeringAshbya gossypiifor efficient biolipid production

“…Thus, a combined strategy aimed at increasing both the levels of acetyl-CoA and NADPH has been used for the production of fatty acid ethyl esters and polyhydroxybutyrate. [19][20][21] Many culture medium formulations for microbial fermentations are based on waste/low-cost sugars and it is therefore important to improve lipid accumulation from sugar-based media. 22 In this sense, the pox1D strains generated in our work were able to produce up to 9% of their CDW as lipids in rich glucose-rich medium (Fig.…”