Remarkably stable biofuel enzymes obtained from microbial community

This 50-milliliter flask contains a symbiotic mix of bacteria derived from compost that was maintained for three years. (Credit: Steve Singer/JBEI)
This 50-milliliter flask contains a symbiotic mix of bacteria derived from compost that was maintained for three years. (Credit: Steve Singer/JBEI)

Newly published research has demonstrated the importance of microbial communities as a source of stable enzymes that could be used to convert plants to biofuels.

The research was carried out by scientists from the Department of Energy’s Joint BioEnergy Institute (JBEI) based at Lawrence Berkley National Laboratory. The findings have been published in the journal Nature Microbiology, and report on the discovery of new types of cellulases - enzymes that help break down plants into ingredients that can be used to make biofuels and bioproducts, according to a JBEI statement.

Unlike traditional methods, the cellulases were cultured from a microbial community or microbiome. Usually, isolated organisms are used to obtain enzymes.

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

“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. This opens up the opportunity to discover new types of enzymes that are only produced by microbes in communities.”

It was revealed that the bacterial population Candidatus Reconcilibacillus cellulovorans yielded cellulases that were arranged in ‘remarkably robust carbohydrate-protein complexes’, a structure never before observed in isolates.

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

This stability makes the new cellulose complexes attractive for applications in biofuels production, the authors say. In particular, it gives the cellulases an advantage over alternatives that degrade more rapidly at high tremperature.

 

Industrial scale

JBEI scientists collaborated with researchers from the Advanced Biofuels and Bioproducts Process Demonstration Unit (ABPDU) at Berkeley Lab, a scale-up facility established by DOE to help accelerate the commercialisation of biofuels research discoveries, to determine whether the enzyme production could be scaled up for industrial applications.

While the JBEI scientists were able to produce 50 millilitre samples at the DOE Bioenergy Research Centre, in just six weeks the scientists at ABPDU scaled the cultures to a volume 6,000 times larger, 300 litres, in industrial bioreactors.

Sebastian Kolinko, a JBEI postdoctoral researcher, is the study’s lead author.

This 50-milliliter flask contains a symbiotic mix of bacteria derived from compost that was maintained for three years. (Credit: Steve Singer/JBEI)