lignocellulose depolymerization
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Lignins are the most abundant biopolymers that consist of aromatic units. Lignins are obtained by fractionation of lignocellulose in the form of "technical lignins". The depolymerization (conversion) of lignin and the treatment of depolymerized lignin are challenging processes due to the complexity and resistance of lignins. Progress toward mild work-up of lignins has been discussed in numerous reviews. The next step in the valorization of lignin is the conversion of lignin-based monomers, which are limited in number, into a wider range of bulk and fine chemicals. These reactions may need chemicals, catalysts, solvents, or energy from fossil resources. This is counterintuitive to green, sustainable chemistry. Therefore, in this review, we focus on biocatalyzed reactions of lignin monomers, e.g., vanillin, vanillic acid, syringaldehyde, guaiacols, (iso)eugenol, ferulic acid, p-coumaric acid, and alkylphenols. For each monomer, its production from lignin or lignocellulose is summarized, and, mainly, its biotransformations that provide useful chemicals are discussed. The technological maturity of these processes is characterized based on, e.g., scale, volumetric productivities, or isolated yields. The biocatalyzed reactions are compared with their chemically catalyzed counterparts if the latter are available.
The bacterium Pseudomonas putida KT2440 is gaining considerable interest as a microbial platform for biotechnological valorization of polymeric organic materials, such as lignocellulosic residues or plastics. However, P. putida on its own cannot make much use of such complex substrates, mainly because it lacks an efficient extracellular depolymerizing apparatus. We seek to address this limitation by adopting a recombinant cellulosome strategy for this host. In this work, we report an essential step in this endeavor-a display of designer enzyme-anchoring protein "scaffoldins", encompassing cohesin binding domains from divergent cellulolytic bacterial species on the P. putida surface. Two P. putida chassis strains, EM42 and EM371, with streamlined genomes and differences in the composition of the outer membrane were employed in this study. Scaffoldin variants were optimally delivered to their surface with one of four tested autotransporter systems (Ag43 from Escherichia coli), and the efficient display was confirmed by extracellular attachment of chimeric β-glucosidase and fluorescent proteins. Our results not only highlight the value of cell surface engineering for presentation of recombinant proteins on the envelope of Gram-negative bacteria but also pave the way toward designer cellulosome strategies tailored for P. putida.
- MeSH
- beta-glukosidasa metabolismus MeSH
- celulosa metabolismus MeSH
- celulozómy metabolismus MeSH
- chromozomální proteiny, nehistonové chemie MeSH
- Escherichia coli metabolismus MeSH
- genom bakteriální * MeSH
- membránové proteiny metabolismus MeSH
- metabolické inženýrství metody MeSH
- proteinové domény MeSH
- proteiny buněčného cyklu chemie MeSH
- proteiny z Escherichia coli metabolismus MeSH
- Pseudomonas putida genetika metabolismus MeSH
- rekombinantní proteiny metabolismus MeSH
- vnější bakteriální membrána metabolismus MeSH
- zelené fluorescenční proteiny metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
