Research Highlights

Extremophile Microbes Improve Soybean Oil Extraction Efficiency

By Sarah Hill

Squeezing every ounce of value out of soybeans would allow the agriculture industry to maximize soybean processing. One example of extracting additional value is through a process called biohydrolysis, which a University of Nebraska researcher has perfected to utilize even the indigestible parts of the soybean.

What is Biohydrolysis?

Plants that are woody or hard can be softened to make that material more digestible and allow it to be converted into other materials. When the oil is released through soybean processing, cellulose becomes trapped in part of the bean.

“Feedstocks contain lignocellulose, a mix of lignin, cellulose and hemicellulose, which are the woody, or undigestible components of soybeans,” says Paul Blum, University of Nebraska professor of biological sciences. “It’s also referred to as deconvolution in the corn ethanol industry.”

Biohydrolysis uses an enzyme to break apart the long chains of sugars found in soybeans. The process converts cellulose into fermentable sugar, turning a low-value product into something value-added.

Putting Extremophiles to Work

Blum, a microbiologist by training with more than 30 years of experience, works with microbes called extremophiles, which thrive in unusual conditions. He has created a unique, proprietary enzyme cocktail called Extremase to treat soybeans during processing. Extremase is optimized with different enzymes that have complimentary activity, resulting in more soybean oil being extracted. 

“The microbes used to create Extremase come from geothermal hot springs, where the environment is acidic, with a low pH and a high temperature of 112-212 degrees Fahrenheit,” Blum explains. “Those conditions mimic soybean processing, so the microbe thrives because it’s in an environment where it naturally wants to be.”

In addition, the thermostable microbes in Extremase naturally inhibit other microbial contaminants, so the end product is more pure. 

Producing Diesel from Soybean Oil

Biodiesel is typically produced by chemically converting soybean oil to diesel, so improving extraction efficiency to get more soybean oil will also increase biodiesel production.

“We checked the soybean oil composition from oil extracted using Extremase,” says Blum. “The enzyme cocktail doesn’t change the composition of the soybean oil components, so there will be no effect on the biodiesel produced using the more efficient extraction process, but it yields 50% more soybean oil relative to processing.”

Using Extremase also allows soybean processors the ability to process older soybeans than are usually processed for ethanol.

“Another major benefit is converting low-value lignocellulosic material into value-added sugar, which isn’t usually recognized by the soybean industry because it’s largely used as a feed additive after the oil is extracted,” Blum says. “However, that sugar can be used to make high-value products, such as ethanol.”

Huge Cost Savings

Despite adding another input into the processing, mixing in Extremase ends up costing less than a penny per pound of soybeans. The tradeoff is more soybean oil and high-value sugar.

“Currently with ethanol production, the expense to the grower is 4 cents per gallon,” Blum says. “A competitor’s product costs soybean growers 44 cents per gallon, so Extremase is significantly cheaper.”

Extremase can be reused multiple times, which provides another dramatic cost savings. The enzyme cocktail doesn’t need to be frozen and has a long shelf life, so soybean processors can purchase it and leave it on the shelf until it’s needed, and then reuse it multiple times.

Published: Aug 7, 2023