Nonconventional yeasts in the spotlight with bioenergy research led by CBE’s Shao

Biofuels and bioproducts continue to be an area of great significance in the worldwide quest to reduce greenhouse gasses and to develop sustainable energy resources.

Department of Chemical and Biological Engineering (CBE) associate professor Zengyi Shao is part of a large group of investigators at work in this arena with support from the Department of Energy (DOE) CABBI (Center for Advanced Bioenergy and Bioproducts Innovation). It’s one of four DOE Biorenewable Research Centers and exists to develop efficient ways to grow bioenergy crops, transform biomass into valuable chemicals, and market the resulting biofuels and other bioproducts.

“Probing the integration and expression hotspots of nonconventional yeasts for producing high-value chemicals” is a to-be-published group research discovery that includes Shao and is supported by more than $447,000 from DOE for a three-year period.

The research centers on engineering of three nonconventional yeasts as the production hosts for wax esters and itaconic acid. Itaconic acid is a biopolymer precursor and wax esters are premier lubricants. “Development of those nonconventional microbes as production hosts is currently constrained by the lack of efficient genetic manipulation tools,” said Shao.

“My group is working on applying a transposon-mediated strategy and the nonhomologous end-joining mechanism to probe the integration and expression hotspots that will significantly enhance the production.” A transposon is a class of genetic elements that can “jump” to different locations within a genome. “The goal is to improve the production levels of wax esters and itaconic acid,” Shao explained. “The amount of the enzymes catalyzing the synthesis reactions is dependent on where we insert the corresponding genes. We are exploring two strategies to identify the optimal insertion location.”

“Currently, we are developing an itaconic acid biosensor to facilitate the screening of high-producing variants and investigating the production of wax esters from soybean-derived oils,” Shao reported, and explained the importance of the research: “The sensor is needed to enable high-throughput screening of high-producing variants created based on genome-scale mutagenesis. The typical screening format relying on analytic equipment can give an accurate quantification, but the screening throughput is only dozens per day. The sensor we are constructing allows for the screening of hundreds of clones per day.”

Postdoctoral research associate Yuxin Zhao and graduate student Wan Sun are also involved in this project.

Additionally, Shao’s Iowa State University research group is at work on “Leveraging the Hermes Transposon to Accelerate the Development of Nonconventional Yeast-based Microbial Cell Factories,” a research project supported by an Iowa State University bioscience-based research seed grant made possible through funding by the Iowa Legislature.

It’s one of two biobased projects university-wide to receive this funding through the Office of Vice President for Research to encourage industry-university collaborations. Industry partners on the project are Kemin Industries, Cargill and Puretein Bioscience. The effort deals with genetic engineering of high-performance yeast strains to create microbial mediums that offer the potential to more cost-efficiently produce larger quantities of high-value compounds.