Integrated process development for grass biomass utilization through enzymatic saccharification and upgrading...

Area of Science:

• Biomass Valorization
• Synthetic Biology
• Green Chemistry

Background:

• Hydroxycinnamic acids (HCAs) are key components in grass biomass, crosslinking lignin and polysaccharides.
• Mild alkaline extraction can recover HCAs, but heterogeneity poses challenges.
• HCAs are precursors for valuable bio-based chemicals.

Purpose of the Study:

• To develop a green process for the total valorization of grass biomass.
• To efficiently convert heterogeneous HCAs into specific bio-based building blocks.
• To improve enzymatic saccharification of lignocellulose after HCA extraction.

Main Methods:

• Extraction of HCAs from bamboo and rice straw using mild alkaline pretreatment.
• Microbial funneling using engineered Pseudomonas putida PpY1100 to convert HCAs.
• Production of 2-pyrone-4,6-dicarboxylic acid (PDC) and (4S)-3-carboxymuconolactone (4S-3CML).
• Assessment of enzymatic saccharification efficiency of lignocellulose post-HCA extraction.

Main Results:

• Engineered P. putida PpY1100 achieved high titers (3.9-9.3 g/L) and molar yields (92-99%) for PDC and 4S-3CML.
• Enzymatic saccharification efficiency increased significantly: 8.9-fold for bamboo and 6.8-fold for rice straw.
• Demonstrated a method for upgrading heterogeneous HCAs into valuable single chemicals.

Conclusions:

• A green-like process integrates HCA upgrading with enhanced lignocellulose saccharification for total grass biomass valorization.
• Microbial funneling offers an efficient route to produce bio-based polymer building blocks from grass biomass.
• This approach contributes to sustainable biorefinery strategies.