Co-production of 3-hydroxypropionic acid and 1,3-propanediol from glycerol using resting cells of recombinant Klebsiella pneumoniae J2B strain overexpressing aldehyde dehydrogenase

Abstract

The co-production of 3-hydroxypropionic acid (3HP) and 1,3-propanediol (PDO) from glycerol was studied using the resting cells of a recombinant Klebsiella pneumoniae J2B strain that overexpresses an aldehyde dehydrogenase (KGSADH). Active biomass was produced in a mineral salt medium containing yeast extract and glycerol under a range of aeration conditions, and shifted to potassium phosphate buffer containing glycerol for bioconversion. The microaerobic or anaerobic conditions were favorable for both the production of active biomass and subsequent bioconversion. At the flask level, the recombinant strain (2.0g CDW/L) grown under microaerobic conditions produced 43.2mM 3HP and 59.0mM PDO from glycerol (117mM) in 30min with a cumulative yield of 0.87 (mol/mol). The fed-batch bioconversion, which was performed in a 1.5-L bioreactor with 1.0g CDW/L at a constant pH7.0 under anaerobic conditions, resulted in 125.6mM 3HP and 209.5mM PDO in 12h with a cumulative overall productivity, yield, and maximum specific production rate of 27.9mmol/L/h, 0.71 (mol/mol), and 128.5mmol/g CDW/h, respectively. Lactate, succinate and 2,3-butanediol were the major by-products, whereas the production of acetate and ethanol was marginal. This is the first report of the simultaneous production of 3HP and PDO from glycerol using a resting cell system.