High-titer, antibiotic-free, pilot-scale production of 1,3-propanediol by engineered Corynebacterium

Abstract

The microbial valorization of glycerol, a major biodiesel byproduct, into high-value chemicals remains challenging at industrially competitive titers. Here we engineered Corynebacterium glutamicum for high-level 1,3-propanediol (1,3-PDO) production, validating each step via fed-batch fermentation. First, C. glutamicum ATCC 13032 was metabolically engineered to produce 138 g l−1 1,3-PDO from glucose–glycerol and 100.9 g l−1 from glycerol alone. Key engineering strategies included establishing glycerol uptake and 1,3-PDO biosynthetic pathways, minimizing byproducts and optimizing fed-batch fermentation. We then transferred these strategies to a newly isolated strain, C. glutamicum SC97. Further engineering, including antibiotic-free plasmid addiction system and sucCD overexpression, enabled 141.5 g l−1 1,3-PDO at 2.95 g l−1 h−1 without antibiotics. Scalability was demonstrated at 30-l and 300-l pilot-scale fermentations, reaching 120.2 g l−1 and 127.8 g l−1 of 1,3-PDO, respectively. Techno-economic and life-cycle assessments support industrial feasibility and environmental impact, providing a robust blueprint for sustainable microbial 1,3-PDO production at scale. This study reports on engineered Corynebacterium glutamicum capable of converting glycerol, a major biodiesel byproduct, into 1,3-propanediol at industrially relevant titers. Through integrated strain design, optimization of fed-batch conditions, implementation of antibiotic-free systems and validation in pilot-scale fermentation, this study establishes a scalable blueprint for sustainable 1,3-propanediol biomanufacturing.