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Valdehuesa, Kris Niñ,o G.,Liu, Huaiwei,Nisola, Grace M.,Chung, Wook-Jin,Lee, Seung Hwan,Park, Si Jae Springer-Verlag 2013 Applied microbiology and biotechnology Vol.97 No.8
<P>Development of sustainable technologies for the production of 3-hydroxypropionic acid (3HP) as a platform chemical has recently been gaining much attention owing to its versatility in applications for the synthesis of other specialty chemicals. Several proposed biological synthesis routes and strategies for producing 3HP from glucose and glycerol are reviewed presently. Ten proposed routes for 3HP production from glucose are described and one of which was recently constructed successfully in Escherichia coli with malonyl-Coenzyme A as a precursor. This resulted in a yield still far from the required level for industrial application. On the other hand, strategies employing engineered E. coli and Klebsiella pneumoniae capable of producing 3HP from glycerol are also evaluated. The titers produced by these recombinant strains reached around 3 %. At its current state, it is evident that a bulk of engineering works is yet to be done to acquire a biosynthesis route for 3HP that is acceptable for industrial-scale production.</P>
Valdehuesa, Kris Niñ,o G.,Lee, Won-Keun,Ramos, Kristine Rose M.,Cabulong, Rhudith B.,Choi, JiSoo,Liu, Huaiwei,Nisola, Grace M.,Chung, Wook-Jin Springer-Verlag 2015 BIOPROCESS AND BIOSYSTEMS ENGINEERING Vol.38 No.9
<P>Biosynthetic pathways for the production of biofuels often rely on inherent aldehyde reductases (ALRs) of the microbial host. These native ALRs play vital roles in the success of the microbial production of 1,3-propanediol, 1,4-butanediol, and isobutanol. In the present study, the main ALR for 1,2,4-butanetriol (BT) production in Escherichia coli was identified. Results of real-time PCR analysis for ALRs in EWBT305 revealed the increased expression of adhP, fucO, adhE, and yqhD genes during BT production. The highest increase of expression was observed up to four times in yqhD. Singular deletion of adhP, fucO, or adhE gene showed marginal differences in BT production compared to that of the parent strain, EWBT305. Remarkably, yqhD gene deletion (KBTA4 strain) almost completely abolished BT production while its re-introduction (wild-type gene with its native promoter) on a low copy plasmid restored 75?% of BT production (KBTA4-2 strain). This suggests that yqhD gene is the main ALR of the BT pathway. In addition, KBTA4 showed almost no NADPH-dependent ALR activity, but was also restored upon re-introduction of the yqhD gene (KBTA4-2 strain). Therefore, the required ALR activity to complete the BT pathway was mainly contributed by YqhD. Increased gene expression and promiscuity of YqhD were both found essential factors to render YqhD as the key ALR for the BT pathway.</P>