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It may take a microbial village to find the next generation of biofuel enzymes.

Researchers from the U.S. Department of Energy’s Joint BioEnergy Institute (JBEI) at the Lawrence Berkeley National Laboratory have found that microbial communities can be a source of stable enzymes that could be used to produce new biofuels from plants.

The researchers discovered new types of cellulases—enzymes that help break down plants into ingredients that can be used to make biofuels and bioproducts—that were cultured from a microbiome.

Using a microbial community veers from the approach typically taken of using isolated organisms to obtain enzymes.

The scientists studied the microbial menagerie present in municipal compost and found that 70 percent of the enzymatic activity originated from cellulases produced by a cluster of uncultivated bacteria in the compost.

They also discovered that the enzymes easily broke down the cellulose in plant biomass into glucose at temperatures up to 80 degrees Celsius.

“Here we're cultivating an entire community of microbes to access enzymes that we couldn't get from isolates,” study principal investigator Steve Singer, Ph.D., a senior scientist in Berkeley Lab's Biological Systems and Engineering Division and director of Microbial and Enzyme Discovery at JBEI, said in a statement. “Some microbes are difficult to culture in a lab.

“We are cultivating microbes living in communities, as they occur in the wild, which allows us to see things we don't see when they are isolated,” he added. “This opens up the opportunity to discover new types of enzymes that are only produced by microbes in communities.”

The bacterial population—Candidatus Reconcilibacillus cellulovorans—yielded cellulases that were arranged in robust carbohydrate-protein complexes, a structure never before observed in isolates that makes them attractive for applications in biofuels production.

“The enzymes persist, even after a decline in bacterial abundance,” Singer said. “We kept the microbial community cultivation going for more than three years in the lab.”

According to Singer, the stability of this cellulases is an advantage because other cellulases degrade more rapidly at high temperatures.

The study was published in Nature Microbiology

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