P77
Microbial Metabolism of Levulinic Acid and γ-Valerolactone
Sunday, August 2, 2015
Non-enzymatic sugar production is a promising alternative for second-generation biofuel production over traditional enzymatic hydrolysis due to its potential for lower cost and better scalability. Recently, it has been shown that biomass can be efficiently converted to two simple 5 carbon molecules γ-valerolactone (GVL) and levulinic acid (LA). A limited number of microbes possess the capability to consume these molecules and it is predicted they are catabolized through the same pathway, however the enzymes responsible have not been elucidated. In this work, we have isolated an enzyme that is capable of hydrolyzing GVL to form 4-hydroxyvalerate (4-HV), the first step in GVL catabolism. The formation of 4-HV is also the first step in the catabolism of LA. The laboratory microbe, Pseudomonas putida, can readily consume LA as its sole carbon source. Transposon studies in P. putida identified an operon involved in the LA metabolic pathway and through knockout and complementation studies we have confirmed the involvement of the operon in LA catabolism. We have also engineered E. coli for the utilization of LA and GVL as a carbon source. This research will allow microbial upgrading of a more cost effective biomass hydrolysis to a variety of fuels and chemicals in a potentially economically viable manner.