18-21: Evolving and engineering Actinobacillus succinogenes for succinate production from lignocellulose hydrolysate

Renewable bio-based industrial products are being intensively studied as alternatives to petroleum-based products, whose production releases teragrams of carbon dioxide equivalents as well as hundreds of thousands of tons of pollutants. Succinate is currently synthesized in small amounts to fulfill the needs of a small specialty chemical market. With an optimized biological production method from a renewable substrate, succinate’s versatility as a chemical feedstock could expand succinate’s market to a $15 billion industrial products market, reducing our reliance on petroleum. The bacteria Actinobacillus succinogenes naturally produces succinate at a higher titer and rate than most engineered E. coli strains, making it a clear choice for further engineering and optimization.

A. succinogenes has been grown and transferred on lignocellulosic sugars to selectively evolve it for rapid growth. Further evolution was performed by growing the evolved strain on ammonia fiber expansion-treated corn stover hydrolysate to adapt it to the desired substrate and possible growth inhibitors. The evolved strains have been sequenced and analysis is underway to identify mutations responsible for increased growth rates. Growth rate and fermentation balance analyses have been completed to confirm that strain evolution did not negatively affect succinate production. The strain evolved for rapid growth on corn stover hydrolysates will be engineered to generate a strain that grows quickly and produces large amounts of succinate efficiently.