Bioprospectors identify new biohydrogen and ethanol producing bacteria in Iceland's hot springs
A bioprospecting expedition to Iceland's famed hot springs has yielded new strains of bacteria with potential of producing biohydrogen (H2) and ethanol (EtOH) fuels from biomass and waste materials containing carbohydrates. The report about the discovery of the new thermophilic microbes appeared online as an open access article in Energy & Fuels, a bi-monthly journal. This is yet another illustration of how investigating life in extreme environments may yield applications in the emerging bioeconomy.
In the study, Perttu E. P. Koskinen and colleagues point out that ethanol and hydrogen are two leading eco-friendly candidates for supplementing world supplies of oil, coal, and other conventional fuels. Research suggests that there would be advantages in producing those fuels by fermentation with bacteria capable of withstanding higher temperatures than microbes now in use.
Knowing that thermophilic, or heat-loving, bacteria inhabit Iceland's hot springs, the scientists bioprospected scalding-hot geothermal springs in different parts of the country for new ethanol and hydrogen-producing bacteria. After screening samples, including those from springs that approached the boiling point of water, the scientists enriched promising microorganisms that can produce the compounds from glucose or cellulose at high temperatures. The enrichments included those with unusually high yields of hydrogen or ethanol from carbohydrates.
Hydrogen- and EtOH-producing enrichment cultures were obtained from various hot spring samples over a temperature range of 50–78 °C. The temperature dependencies for the most promising enrichments were determined with a temperature-gradient incubator. One of the enrichments (33HL) produced 2.10 mol of H2/mol of glucose at 59 °C. Another enrichment (9HG), dominated by bacteria closely affiliated with Thermoanaerobacter thermohydrosulfuricus, produced 0.68 mol of H2/mol of glucose, and 1.21 mol of EtOH/mol of glucose at 78 °C:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: ethanol :: biohydrogen :: biochemistry :: microbes :: fermentation :: thermophilic ::
Hydrogen and EtOH production by 9HG was characterized further in a continuous-flow bioreactor at 74 °C. The highest H2 and EtOH yields of 9HG were obtained at pH 6.8 ± 0.3. Lactate production decreased the H2 and EtOH yields in the continuous-flow bioreactor, and the yields were lower than those obtained in the batch fermentations.
In conclusion, the thorough batch screening of Icelandic hot spring samples indicated promising enrichments for H2 or H2 plus EtOH production from carbohydrate materials.
References:
Perttu E. P. Koskinen, Chyi-How Lay, Steinar R. Beck, Katariina E. S. Tolvanen, Anna H. Kaksonen, Jóhann Örlygsson, Chiu-Yue Lin, and Jaakko A. Puhakka, "Bioprospecting Thermophilic Microorganisms from Icelandic Hot Springs for Hydrogen and Ethanol Production", Energy & Fuels, ASAP Article, October 18, 2007, DOI: 10.1021/ef700275w
Eurekalert: Bioprospectors identify hot new biofuel-producing bacteria - December 3, 2007.
Biopact: Investigating life in extreme environments may yield applications in the bioeconomy - July 05, 2007
In the study, Perttu E. P. Koskinen and colleagues point out that ethanol and hydrogen are two leading eco-friendly candidates for supplementing world supplies of oil, coal, and other conventional fuels. Research suggests that there would be advantages in producing those fuels by fermentation with bacteria capable of withstanding higher temperatures than microbes now in use.
Knowing that thermophilic, or heat-loving, bacteria inhabit Iceland's hot springs, the scientists bioprospected scalding-hot geothermal springs in different parts of the country for new ethanol and hydrogen-producing bacteria. After screening samples, including those from springs that approached the boiling point of water, the scientists enriched promising microorganisms that can produce the compounds from glucose or cellulose at high temperatures. The enrichments included those with unusually high yields of hydrogen or ethanol from carbohydrates.
Hydrogen- and EtOH-producing enrichment cultures were obtained from various hot spring samples over a temperature range of 50–78 °C. The temperature dependencies for the most promising enrichments were determined with a temperature-gradient incubator. One of the enrichments (33HL) produced 2.10 mol of H2/mol of glucose at 59 °C. Another enrichment (9HG), dominated by bacteria closely affiliated with Thermoanaerobacter thermohydrosulfuricus, produced 0.68 mol of H2/mol of glucose, and 1.21 mol of EtOH/mol of glucose at 78 °C:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: ethanol :: biohydrogen :: biochemistry :: microbes :: fermentation :: thermophilic ::
Hydrogen and EtOH production by 9HG was characterized further in a continuous-flow bioreactor at 74 °C. The highest H2 and EtOH yields of 9HG were obtained at pH 6.8 ± 0.3. Lactate production decreased the H2 and EtOH yields in the continuous-flow bioreactor, and the yields were lower than those obtained in the batch fermentations.
In conclusion, the thorough batch screening of Icelandic hot spring samples indicated promising enrichments for H2 or H2 plus EtOH production from carbohydrate materials.
References:
Perttu E. P. Koskinen, Chyi-How Lay, Steinar R. Beck, Katariina E. S. Tolvanen, Anna H. Kaksonen, Jóhann Örlygsson, Chiu-Yue Lin, and Jaakko A. Puhakka, "Bioprospecting Thermophilic Microorganisms from Icelandic Hot Springs for Hydrogen and Ethanol Production", Energy & Fuels, ASAP Article, October 18, 2007, DOI: 10.1021/ef700275w
Eurekalert: Bioprospectors identify hot new biofuel-producing bacteria - December 3, 2007.
Biopact: Investigating life in extreme environments may yield applications in the bioeconomy - July 05, 2007
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