"For years, we have been researching cost-effective ways to break down lignin and convert it into valuable platform chemicals," Sandia bioengineer Seema Singh said.
"We applied our understanding of natural lignin degraders to E. coli because that bacterium grows fast and can survive harsh industrial processes," she added in the work published in the Proceedings of the National Academy of Sciences of the United States of America,.
(Source: Sandia National Laboratories,
IANS, Quint, 19 May, 2018) Contact: Sandia National Laboratories, Seema Singh, Bioengineering, (925) 294-4551, www.jbei.org/wp-content/uploads/2013/06/Seema-Singh_CV_JBEI.pdf
More Low-Carbon Energy News Lignin, Biofuel, Biochemical, Renewable Fuel, Sandia National Laboratories,
A major focus of research at JBEI, and in the broader community of biofuel researchers, is the production of industrially and commercially relevant fuels and chemicals from renewable resources, such as lignocellulosic biomass, rather than from petroleum. The enzyme discovered in this study will enable the first-time microbial production of bio-based toluene, and in fact, the first microbial production of any aromatic hydrocarbon biofuel.
The enzyme discovery resulted from the intensive study of two very different microbial communities that produced toluene. One community contained microbes from lake sediment, and the other from sewage sludge. Since microbes in the environment are a reservoir of enzymes that catalyze an extraordinarily diverse set of chemical reactions, it's not unusual for scientists working in biotechnology to source enzymes from nature.
The toluene-synthesizing enzyme discovered in this study, phenylacetate decarboxylase, belongs to a family of enzymes known as glycyl radical enzymes (GREs). The radical nature of GREs allows them to catalyze chemically challenging reactions, such as anaerobic decarboxylation of phenylacetate to generate toluene.
In fact, metagenome analyses revealed that these microbial communities each contained more than 300,000 genes - the equivalent of more than 50 bacterial genomes. Another challenge was that the anaerobic microbial communities and many of their enzymes were sensitive to oxygen, forcing the scientists to manipulate cultures and enzymes under strictly anaerobic conditions.
The discovery process combined protein purification techniques used by biochemists for decades, such as fast protein liquid chromatography, with modern metagenomic, metaproteomic, and associated bioinformatic analyses, some of which were carried out in collaboration with the Joint Genome Institute, a DOE Office of Science User Facility. An important component of the discovery process was to validate the researchers' predictions of the toluene biosynthesis enzyme with experiments using highly controlled assays involving purified proteins.
The researchers believe that their study results have implications for fundamental and applied science. From a biochemical perspective, the study expands the known catalytic range of GREs, and from a biotechnological perspective, it will enable first-time biochemical synthesis of an aromatic fuel hydrocarbon from renewable resources.
(Source: Lawrence Berkeley National Laboratory, 26 Mar., 2018) Contact: DOE Joint BioEnergy Institute, www.jbei.org; LBNL, Harry Beller, Snr. Scientist, JBEI scientific lead, (510) 486-7321, HRBeller@lbl.gov,
More Low-Carbon Energy News JBEI, LBNL, Enzyme, Biofuel ,
JBEI was among three BRCs established by DOE a decade ago to accelerate fundamental research in advanced, next-generation biofuels, and to make such technology cost-effective and widely available. The other two centers were the BioEnergy Science Center, led by Oak Ridge National Laboratory, and the Great Lakes Bioenergy Research Center, led by the University of Wisconsin-Madison in partnership with Michigan State University.
To date, JBEI research has yielded 672 peer-reviewed publications, 85 licenses, 23 patents, and five startups. JBEI has contributed to many scientific achievements, including:
engineering bioenergy crops to increase sugar-containing polymers and decrease lignin in plant cell walls;
developing an affordable and scalable ionic liquid pretreatment technology;
developing microbial routes for the conversion of biomass-derived sugars into advanced, "drop-in" blendstocks for gasoline, diesel, and jet fuels.
(Source: JBEL, PR, 17 July, 2017) Contact: LBL, www.lbl.gov;
DOE Office of Science, science.energy.gov
The work, being conducted at the Joint BioEnergy Institute (JBI), targets LigM for its role in breaking down aromatic pollutants such as aryl compounds, a common waste product from industrial and agricultural practices, into something of value.
LigM is utilised by the soil bacterium Sphingomonas to metabolize aryl compounds derived from lignin, the stiff, organic material that gives plants their structure. In biofuel production, aryl compounds are a byproduct of the breakdown of lignin. Many of the pathways leading to the breakdown of lignin involve demethylation, which is often a critical precursor to any additional steps in modifying lignin-derived aryl compounds.
The researchers found that half of the LigM enzyme was homologous to known structures with a tetrahydrofolate-binding domain that is found in simple and complex organisms alike. The other half of LigM's structure was said to be completely unique, providing a starting point for determining where its aryl substrate-binding site is located.
Study lead author Amanda Kohler, JBEI postdoctoral researcher at Sandia, noted that LigM is an attractive demethylase for use in aromatic conversion because it is a simple, single-enzyme system. LigM is also able to maintain its functionality over a broad temperature range.(Source: Berkeley Lab, National Academy of Science, WMW, 2 May, 2017) Contact: LBL Berkeley, Sandia National Lab, Amanda Koehler, (530) 902-8670, ACKohler@lbl.gov, www.lbl.gov; Sandia National Lab., www.sandia.gov
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