Channelling carbon flux through the meta‐cleavage route for improved poly(3‐hydroxyalkanoate) production from benzoate and lignin‐based aromatics in Pseudomonas putida H

Abstract

Engineered P. putida H sets a benchmark in lignin‐based PHA. Balancing the catechol degrading pathways enables improved PHA production. A DO‐stat fed‐batch process permits the efficient conversion of lignin hydrolysates into biomass and biopolymer.

Lignin Aromatics to PHA Polymers: Nitrogen and Oxygen Are the Key Factors for Pseudomonas

“…Together with ongoing important metabolic engineering efforts for strain development on improving lignin aromatic uptake, balancing of carbon flux and avoiding mcl-PHA reassimilation, 8,11,19,20,51,55,56 we encourage future research on linking aspects like: media formulation (i.e., optimization of nutrients like nitrogen amount to ratio of real mixed lignin fractions), 2 oxygen fine-tuned feeding strategies (i.e., DO stat fed batch cultivations) 59 to improve mcl-PHA concentrations and minimize diauxic aromatic uptake profiles during different nitrogen availability (i.e., "feast and famine" stages), synergistic cocarbon feeding strategies to balance metabolic energy 17,21,60 and ensuring final product quality (i.e., mcl-PHA material properties). 16 The outcomes of this in depth bioprocess understanding may also benefit the production of other value compounds than mcl-PHA from lignin aromatics.…”

“…Furthermore, limited methods for analysis of the heterogeneous aromatic fractions and complex catabolic repression phenomena make a detailed physiological study on mcl- PHA production from liquors obtained after lignin depolimerization very challenging. Therefore, much of the physiological research thus far focused on the evaluation of single lignin-derived aromatic compounds like benzoate, , vanillate, ferulate, or cofeeding some of them with glycerol . Thus, detailed studies toward a physiological understanding of the uptake and conversion dynamics of defined aromatic mixtures into mcl- PHA are necessary.…”

Integrated chemo‐ and biocatalytic processes: a new fashion toward renewable chemicals production from lignocellulosic biomass

“…For example, the hydrogenolysis of switchgrass lignin using Pd/C yielded 7,8‐dihydro‐ p ‐coumaric acid methyl ester and 7,8‐dihydroferulic acid methyl ester as major products, which can be converted into PDC with near‐stoichiometric yields by the engineered N. aromaticivorans 93 . Other value‐added products, such as gallate and medium‐chain‐length PHB, are also obtainable from lignin via combined chemical and biological catalysis 94,95 …”

Rational engineering of natural polyhydroxyalkanoates producing microorganisms for improved synthesis and recovery

“…In another study, the deletion of the phaZ depolymerase in KT2440 improved polyester synthesis by 36%, resulting in 2.2 gPHA L −1 in batch cultures (Poblete‐Castro et al, 2014b ) (Table 1 ). Likewise, assessing different feeding modes in fed‐batch bioreactors, the ∆ phaZ P. putida produced 0.34 (gPHA L −1 h −1 ) on crude glycerol, displaying a Mw of 506 KDa and a PDI of 2.6, desirable values for industrial thermoforming (Borrero‐de Acuña et al, 2021a , 2021b ). Nevertheless, the high secretion rate of the side‐product citrate during crude glycerol bioconversion represents a challenge since it had a product yield of 0.6 (g gGlycerol −1 ).…”