Researchers Collaborate to Develop Sorbic Acid Production Process

Achievement date: 
2014
Outcome/accomplishment: 

Researchers in the pyrone testbed at the Center for Biorenewable Chemicals (CBiRC), an NSF-funded Engineering Research Center (ERC) headquartered at Iowa State University, have collaborated across various research thrusts to develop a preliminary sorbic acid production process.

Impact/benefits: 

These collaborative efforts leveraged an Industrial Advisory Board (IAB) partnership with the U.S. Department of Agriculture's National Center for Agriculture Utilization Research (USDA NCAUR) to move the metabolic pathways engineered in two research thrusts into an industrially robust strain for the production of triacetic acid lactone (TAL). In doing so, impressive titers (ways of expressing concentrations) were accomplished, and the research team's techno-economic analysis estimates were independently validated. This undertaking demonstrates CBiRC's power to develop a successful route for obtaining commercially viable levels of biobased chemicals. The interactions, collaborations, and partnerships with members of the IAB add to the likelihood of demonstrating a successful pyrone testbed through an industrial microbe with higher titers and yields and a better understanding of process economics.

Explanation/Background: 

The integrated glucose-to-sorbic-acid process (see figure) was jointly developed by research-thrust teams in addition to CBiRC’s Translational Research Manager. A goal for researchers in the pyrone testbed is to understand mechanisms behind the increased titers and yields by using rational strategies of strain design. These strategies, which encompass a variety of chemical-analysis methods, enable fully grasping the inner workings of cells. By collaborating with NCAUR, several steps in strain design were circumvented because NCAUR has access to one of the largest public collections of microorganisms in the world. Genes and vectors from Thrusts 1 and 2 were transferred to NCAUR for studies in their industrial yeasts. After screening and initial experiments, TAL titers of up to 5.5 g/L were obtained using a modified industrial strain of yeast.

The CBiRC Life Cycle Assessment team (LCA, a CBiRC support area to evaluate sustainability of producing specific biorenewable chemicals) developed an economic model using BioPET (Biorenewables Process Evaluation Tool) for the production of sorbic acid through the TAL intermediate using CBiRC technology. The paper disclosing this information has yielded over 225 downloads.

Independent validation of the team's techno-economic analysis estimates was accomplished through collaboration with MBI International, an IAB member. MBI independently generated a techno-economic analysis for the same process that closely mirrored the results from CBiRC. Also, MBI vetted feasibility of CBiRC’s integrated sorbic acid production process, and no process deal breakers that could not be addressed with expected amounts of further engineering were identified.