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Microbes devour plant material, like leaves and stems from native plants, and convert it into biofuels and bioproducts. But in the process, the deconstructed plant material releases toxins that get in the way, creating one of the challenges to making biofuels an efficient and economical alternative to existing fuels. GLBRC co-investigator Jason Peters and his team are building tools to help make the microbes more resilient.

Traditionally scientists grow “libraries” of mutants — pools of cells with different genes turned off — in the presence of a chemical. Analyzing the surviving cells can provide clues about which genes allow the microbe to tolerate that chemical. But using only one screening method tends to produce false positives, requiring slow and labor-intensive follow-up experiments.  To solve the problem, scientists used two genome screening techniques with complementary strengths and weaknesses to study the effects of inhibitory chemicals on Zymomonas mobilis, a promising microbe for industrial production. Applying the dual-library approach narrowed the field of candidate genes by two thirds. Genes selected for follow-up tests were all true positives. 

Building on previous work evaluating stepwise processing, scientists with the Great Lakes Bioenergy Research Center sought to improve the results with a biorefinery design that combines the first two steps, separating lignin from sugars and breaking into useable pieces with the help of a metal catalyst.

Scientists evaluated how switchgrass responded to drought stress at distinct stages of development — vegetative growth, flowering, and when leaves and shoots die off in the fall (senescence) — and the effects on fermentation of plant sugars. The findings suggest that the timing of drought stress has little impact on plant size but does change fermentation rates. Drought during the growing stage can make plants more hardy at the expense of biofuel production, while late-season drought enhances ethanol yields.

University of Wisconsin–Madison scientists have developed a new method for efficiently pinpointing genes that help microbes resist toxic chemicals, which could enable innovations in biotechnology, medicine, and agriculture.

Over millions of years, plants have developed ways to protect themselves. For example, plants produce special chemicals, or metabolites, to combat harmful microbes, especially fungi. But those same metabolites can make it harder for biorefineries to ferment the plant sugars into fuel or other products with yeast, a type of fungus. 

A team of researchers including current and former Great Lakes Bioenergy Research Center scientists has been honored for their efforts to engineer soybeans that produce an eco-friendly dye and a brain-boosting compound.

Efforts to produce sustainable fuels and chemicals from non-food plants focus on lignin, a part of the cell wall that binds together sugars and gives plants structure. Lignin contains ring-shaped molecules known as aromatics that some microbes can convert into chemicals used to make plastics and other products. But breaking this complex matrix — or polymer — into smaller, useful units is challenging. 

Despite growing interest in Z. mobilis for bioenergy production, scientists have limited understanding of how this treated biomass solution (known as hydrolysate) affects it. So scientists with the Great Lakes Bioenergy Research Center used a systems-level approach to study the microbe’s response to hydrolysate produced from switchgrass treated with a process called ammonia fiber expansion (AFEX). The findings revealed that the hydrolysate triggers a complex stress response, causing changes in the membrane that controls what enters and exits the cell as well as how the microbe digests carbon in the plant sugars.