Microbial polyhydroxyalkanoate production from lignin by Pseudomonas putida NX-1

Abstract

Biological approaches play an important role in lignin valorization, whereas many issues in this area remain unclear. Herein, ligninolytic enzymes in Pseudomonas putida NX-1 were systematically unraveled based on genome sequence technology. Particularly, a dye-decolorizing peroxidase was systematically studied by heterologous expression, enzyme purification, and enzymatic characterization, which suggested it possessed activities on both synthetic dyes and lignin-derived aromatics. Moreover, a complete pathway for polyhydroxyalkanoate biosynthesis was annotated, and the polyhydroxyalkanoate biosynthesis capability of P. putida NX-1 was experimentally confirmed with lignin as the sole carbon source. Furthermore, the monomer compositions, molecular weights, and thermal properties of polyhydroxyalkanoate from glucose and lignin-derived aromatics were comprehensively determined by gas chromatography-mass spectrometry, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. The results indicated that physical properties of polyhydroxyalkanoate prepared from glucose and lignin-derived aromatics were similar, which suggested lignin could be an alternative feedstock for polyhydroxyalkanoate production without compromising its quality.