Redox Balanced Co-production of Propanediol and 3-Hydroxypropionic Acid from Glycerol Using Novel Recombinant Klebsiella quasipneumonia MSN12

The redox imbalance is the major obstacle in the microbial production of 3-hydroxypropionic acid (3-HP). Co- production of propanediol (PDO) and 3- HP is an effective strategy to overcome the redox imbalance issue. The biocatalyst Klebsiella pneumoniae naturally co-produces PDO and 3-HP. Its poor growth characteristics and excessive production of lipopolysaccharide hurdle its usage in industries. The objective of this study is to circumvent these constraints by isolating a novel strain of K. quasipneumoniae MSN12 (KpMSN12) from soil samples. From a numerous isolate, the new isolate KpMSN12 has produced 58 mM PDO and 4 mM 3-HP, when it was grown in shake flask under microaerobic conditions, which is higher than the control Kp109. The effect of overexpression of an aldH (KGSADH) on co-production of 3-HP and PDO from glycerol was investigated in recombinant KpMSN12 (KpMSN12K). KpMSN12K produced 45 mM of 3-HP and 30 mM PDO which was observed higher (3-HP 25 mM, PDO 28 mM) than the control strain. While over expressing dhaB in another recombinant (KpMSN12D), 3-HP was reduced to 9 mM and 11 mM PDO due to the accumulation of 3-HPA and the growth was severely hampered. In addition, combined overexpression of dhaB and aldH (KpMSN12DK) produced 33 mM 3-HP and 25 mM PDO. The lower lipopolysaccharide content in the KpMSN12 strain was confirmed by comparing 2-keto3deoxyoctonate content ( KpMSN12-3.8 mu g/mL; Kp109-5.14 mu g/mL). In addition, this new strain exhibited enhanced sedimentation characteristics and higher susceptibility to a variety of antibiotics when compared to Kp109 strain. These potential characteristics of KpMSN12 would shape it as a desirable host for the production of industrial chemicals. [GRAPHICS] .