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
Article continues
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
Article continues
Monday, December 03, 2007
The bioeconomy at work: researchers develop 'nanohybrid' bioplastic that biodegrades much faster
The plastic is a modified form of polyhydroxybutyrate (PHB), a promising biodegradable thermoplastic produced by the fermentation of renewable biomass by bacteria (previous post) that has been widely hailed as a 'green' alternative to petroleum-based plastic for use in packaging, agricultural and biomedical applications. Although commercially available since the 1980s, PHB has seen only limited use because of its brittleness and unpredictable biodegradation rates.
In the new study, Pralay Maiti, Carl Batt, and Emmanuel Giannelis from Cornell University's Department of Materials Science and Engineering compared the strength and biodegradation rates of raw PHB to a modified form of PHB that contains nanoparticles of clay or 'nanoclays'. One advantage of clay nanocomposites is their improved barrier properties while retaining the flexibility and optical clarity of the pure biopolymer. The use of such particles has been reported in biodegradable aliphatic polyester nanocomposites, but this is the first time they were introduced into PHB/layered silicate nanocomposites:
energy :: sustainability ::biomass :: bioenergy :: biofuels :: biopolymer :: bioplastic :: biodegradable :: nanoclay :: nanocomposite :: bioeconomy ::
The main objective of the researchers was to study the effect of nanoclays on biodegradation. Although the biodegradation of neat PHB enzymatically and in seawater was already studied, this is the first report of biodegradability of PHB nanocomposites.
Biodegradation tests were carried out at room temperature (20 C) and at 60 C. The scientists found that the modified PHB was both stronger and decomposed faster than regular PHB. The nanohybrid PHB decomposed almost completely after seven weeks, while its traditional counterpart showed almost no decomposition (image, click to enlarge). They also showed that degradation could be fine-tuned by adjusting the amount of nanoparticles added.
The study is the first report of the biodegradation of PHB nanocomposites and could lead to wider use of PHB plastics, the scientists say.
Nanotechnology and the field of nano-enhanced bioplastics is having concrete results. Recently a specialty chemicals company announced that it succeeded in embedding dispersible nanoparticles into polylactic acid (PLA) based bioplastics which makes them considerably stronger and less hazy (previous post). This is a much needed improvement, overcoming one of the key weaknesses of PLA bioplastics.
Picture: Polarizing optical images of the virgin bioplastic (PHB) and the 'nanohybrid' (PHBCN2) before and after 8 weeks of biodegradation. The samples were crystallized at 125 °C prior to composting.
References:
Pralay Maiti, Carl A. Batt, Emmanuel P. Giannelis, "New Biodegradable Polyhydroxybutyrate/Layered Silicate Nanocomposites", Biomacromolecules, 8 (11), 3393 -3400, 2007. 10.1021/bm700500t S1525-7797(70)00500-7
Biopact: Nanoparticle additive makes PLA based bioplastics stronger - July 23, 2007
Biopact: Notes on biopolymers in the Global South - March 11, 2007
Article continues
posted by Biopact team at 11:27 PM 0 comments links to this post