A microbial platform for renewable propane synthesis based on a fermentative butanol pathway.

Area of Science:

• Biotechnology
• Synthetic Biology
• Chemical Engineering

Background:

• Propane is a valuable fuel with favorable properties, making it a target for renewable alternatives.
• Existing infrastructure supports propane utilization, driving research into sustainable production methods.
• Current research focuses on microbial biosynthesis of renewable propane, distinct from petroleum-derived fuels.

Purpose of the Study:

• To construct and evaluate novel microbial biosynthetic pathways for renewable propane production.
• To develop alternative CoA-dependent fermentative butanol pathways for propane synthesis.
• To address limitations in precursor availability and enzyme activity for efficient propane biosynthesis.

Main Methods:

• Assembly and evaluation of four synthetic pathways (atoB-adhE2, atoB-TPC7, nphT7-adhE2, nphT7-TPC7).
• Co-expression of aldehyde deformylating oxygenase (ADO) to convert butanol intermediates to propane.
• Optimization strategies including pathway deletion, engineered ADO variants (ADOA134F), and ferredoxin-based electron supply.

Main Results:

• Highest butanol titers achieved with atoB-adhE2 (473 mg/L) and atoB-TPC7 (163 mg/L) routes.
• Propane production was confirmed upon co-expression of ADO.
• The atoB-TPC7-ADO pathway yielded 220 µg/L propane, increased to 3.40 mg/L with optimization.

Conclusions:

• Expanded metabolic toolbox for renewable propane production.
• Provided insights into developing next-generation biofuel platforms.
• Demonstrated a CoA-dependent fermentative butanol pathway with an engineered ADO variant for improved propane synthesis.