(70f) Enhancement of Polyhydroxyalkanoate Production By Co-Feeding Lignin Derivatives with Glycerol in Pseudomonas Putida KT2440

Authors: 
Yang, B., Washington State University Tri-Cities
Xu, Z., Washington State University
Li, X., Washington State University
Hao, N., University of Tennessee
Ragauskas, A. J., University of Tennessee
Pseudomonas putida has great potential for biosynthesis of polyhydroxyalkanoate (PHA) to produce biodegradable plastics. In this study, with co-feeding lignin derivatives (i.e. benzoate, vanillin, and vanillic acid) in addition to glycerol, the cell dry weight and PHA content at 72 h improved by 14%-20% and 49.1%-72.6%, respectively. GC-MS analysis of PHA compositions revealed that the addition of lignin derivatives to glycerol decreased the distribution of long chain monomers (e.g. C10 and C12) of PHA while increased the short chain monomers (e.g. C6 and C8). A newly developed 1H/13C HMBC method that directly examined cell samples without the PHA extraction process confirmed these findings. Further optimization of benzoate/glycerol/nitrogen ratio revealed that the addition of benzoate increased intracellular NADH and NADPH concentrations, indicating the strengthened oxidative stress, consistent with the improvement of both PHA and cell biomass yields. In addition, 1H, 13C and 31P NMR metabolite analysis suggested that the co-feeding of benzoate and glycerol enhanced glycerol consumption, and potentially improved the ED pathway. Overall, this study provides an effective co-carbon feeding strategy to improve PHA yield and lignin conversion.
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