Cold Plasma Treatment Facilitated the Conversion of Lignin-Derived Aldehyde for Pseudomonas putida

Syringaldehyde derived from lignin is one of the essential intermediates for the production of basic chemicals. However, it was poorly understood for the direct microbial conversion of syringaldehyde. Here, this study tried to use cold plasma technique to enhance syringaldehyde conversion for the bacterium Pseudomonas putida. It illustrated that cell growth and syringaldehyde conversion were separately increased by 1.49 times at 3 h and 1.60 times at 6 h for 35 s, 1.16 and 3.44 times for 140 W, and 1.63 and 4.02 times for 105 Pa for P. putida through single factor assays of cold plasma treatment. To be sure, cell growth and syringaldehyde conversion were enhanced by 1.14 and 5.54 times at 3 h under the optimum parameters (35 s, 140 W, and 105 Pa) for P. putida. Furthermore, genome re-sequencing further discovered single-nucleotide polymorphisms of P. putida, such as PP_2589 (A428V), PP_5651 (V82F), and PP_0545 (W335R), and thus indicated that the potential genetic changes derived from cold plasma treatment would be responsible for the acceleration of syringaldehyde conversion. This work would provide a robust strain catalyst and the potential candidate mutation sites for genetic manipulation for microbial bioconversion of the value-added and lignin-based biochemicals.