17 November 2016 2016 01:04 PM GMT

NREL Scientists Discover How Bacterium Uses CO2 And Cellulose To Make Biofuels

Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) made the surprise discovery that a metabolic pathway to take up CO2 exists and functions in a microorganism capable of breaking down and fermenting cellulosic biomass to produce biofuels including hydrogen and hydrocarbons.

Clostridium thermocellum is among the most efficient bacteria indirectly converting cellulosic materials into hydrogen and hydrocarbons biofuels. Most bacteria feeding upon organic carbon compounds, such as glucose or xylose, release CO2 as a waste byproduct, decreasing the maximum amount of products the microorganism can produce per carbon atom measured as carbon efficiency.

Other scientists have found the addition of a form of CO2, known as bicarbonate, into the medium containing the bacterium actually promotes the growth of C. thermocellum, yet its mechanistic details remained a puzzle. This enhanced growth implied the bacterium had the ability to use CO2 and prompted NREL researchers to investigate the phenomena enhancing the bacterium’s growth.

“It took us by surprise that this microbe can recapture some of the CO2 released during growth while they consume sugars derived from cellulosic biomass,” said Katherine J. Chou, a staff scientist with NREL’s Photobiology group and co-author of the new paper “CO2-fixing one-carbon metabolism in a cellulose-degrading bacterium Clostridium thermocellum.” The research is in the new issue of the journal Proceedings of the National Academy of Sciences of the United States of America.

Using carbon isotopes coupled with mass spectrometry analysis, the researchers were able to track how CO2enters the cell, identify the enzymes critical to CO2 uptake, and how CO2 incorporates into products thereby discovering a new metabolic route unknown to the scientific community. Many species of bacteria have the pathway in place for CO2 uptake, but before the new research, the pathway was not associated with the role of carbon dioxide assimilation (otherwise known as CO2 fixation).

The pathway enables the bacterium to use both CO2 and organic carbons during its growth, which is counter-intuitive because it’s much more common for this type of organism to use one and not the other, especially in heterotrophic microbes.

NREL researchers and their collaborators determined adding bicarbonate increased the apparent carbon efficiency of C. thermocellum from 65.7 percent to 75.5 percent. The finding underscores the metabolic plasticity of the microbe and raises various possibilities on how the bacterium is able to use both organic carbons and CO2 without breaking the rules of thermodynamics in energy conservation. The discovery also provides a paradigm shift in the fundamental understandings of carbon metabolism in a cellulose degrading bacterium.

“Our findings pave the way for future engineering of the bacterium as a way to improve carbon efficiency and to reduce the amount of CO2 released into the environment,” Chou said. With the observed improved carbon efficiency, this work inspires future research to redirect more cellular electrons in support of increased hydrogen production, a key goal for the funded research. In addition to Chou, the co-authors from NREL are Wei Xiong, Lauren Magnusson, Lisa Warner, and Pin-Ching Maness. Two BioEnergy Science Center (BESC) co-authors are Paul Lin and James Liao from the University of California, Los Angeles, where Chou earned her Ph.D. in chemical and biomolecular engineering.

The latest research into the bacterium was financed by the NREL Director’s Fellowship Program, Energy Department’s Fuel Cell Technologies Office, as well as Office of Biological and Environmental Research in the DOE Office of Science. NREL is the U.S. Department of Energy’s primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for the Energy Department by The Alliance for Sustainable Energy, LLC.

Photo: Courtesy of National Renewable Energy Laboratory (NREL)

January 10th 2018
US: Doubling Of Wind & Solar Capacity Possible By 2020 as Coal & Nuclear Drop

In the latest issue of its “Energy Infrastructure Update” (with data through November 30, 2017), the Federal Energy Regulatory Commission (FERC) notes that proposed net additions to generating capacity by utility-scale wind and solar could total 115,984 megawatts (MW) by December 2020 – effectively doubling their current installed capacity of 115,520 MW.  The numbers were released as FERC prepares for a January 10 meeting to consider U.S. Department of Energy Secretary Rick Perry’s proposal for a bailout of the coal and nuclear industries.

February 5th 2018
European Parliament Gives A Resounding Vote In Favour Of Clean Energy In Europe

European lawmakers have called for a renewable energy target of 35% for 2030 – rather than the 27% which the European Commission proposed in 2016. The MEPs have now backed measures substantially raising the European Union’s clean-energy ambitions. By 2030, more than one-third of energy consumed in the EU should be from renewable sources such as wind and solar power. The measures are intended to help cut carbon dioxide emissions. The EU is the world’s third-largest emitter of greenhouse gases after China and the United States, releasing about 10% of global emissions. 

February 5th 2018
BASF Turn Hazardous Waste Into Clean Energy At World’s Largest Chemical Complex

Honeywell Process Solutions (HPS) has announced that BASF has opened a state-of-the-art control room equipped with Honeywell Experion® technology at its waste incineration complex in Ludwigshafen, Germany. The plant’s six incinerators process hazardous waste that cannot be reused or recycled and convert it into steam and electrical power. The clean, reusable energy is channelled back into BASF’s production processes, helping the company save resources and reduce emissions. “Thanks to excellent cooperation with Honeywell, our 60-year-old plant now has one of the most modern control rooms in the world,” said Dr Karin Flore, head of waste incineration, BASF.

February 5th 2018
EV, Renewables See CO2 Emissions Plateau By 2030, But Far From 2 Degree Pathway

Major shifts in the global energy landscape, particularly related to electric vehicles (EVs) and renewable energy sources, mean that MEI expects global CO₂emissions to plateau by 2030. However, increased global energy demand means emissions will remain at more than double the level required for a 2 degrees Celsius warming pathway. Ole Rolser, Associate Partner and Solution Leader at MEI, comments: “Despite the significant momentum around EVs and renewable energy sources taking an increasing share of the power market, to realise the 2 degrees pathway scenario, we’d have to see much broader, much more disruptive change than what we’re seeing now.”

February 5th 2018
Chinese Solar Surge Fuels Overall Global Growth In Clean Energy Investment

World clean energy investment totalled $333.5 billion last year, up 3% from 2016 and the second highest annual figure ever, taking cumulative investment since 2010 to $2.5 trillion. An extraordinary boom in photovoltaic installations made 2017 a record year for China’s investment in clean energy. This outpaced changes elsewhere, including jumps in investment in Australia and Mexico, and declines in Japan, the U.K. and Germany. The figures up 3% from a revised $324.6 billion in 2016, and only 7% short of the record figure of $360.3 billion, in 2015.


 

   

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