title: Physiological tolerance and stoichiometric potential of cyanobacteria for hydrocarbon fuel production.
abstract: Cyanobacteria are capable of directly converting sunlight, carbon dioxide and water into hydrocarbon fuel or precursors thereof. Many biological and non-biological factors will influence the ability of such a production system to become economically sustainable. We evaluated two factors in engineerable cyanobacteria which could potentially limit economic sustainability: (i) tolerance of the host to the intended end-product, and (ii) stoichiometric potential for production. Alcohols, when externally added, inhibited growth the most, followed by aldehydes and acids, whilst alkanes were the least inhibitory. The growth inhibition became progressively greater with increasing chain-length for alcohols, whilst the intermediate C6 alkane caused more inhibition than both C3 and C11 alkane. Synechocystis sp. PCC 6803 was more tolerant to some of the tested chemicals than Synechococcus elongatus PCC 7942, particularly ethanol and undecane. Stoichiometric evaluation of the potential yields suggested that there is no difference in the potential productivity of harvestable energy between any of the studied fuels, with the exception of ethylene, for which maximal stoichiometric yield is considerably lower. In summary, it was concluded that alkanes would constitute the best choice metabolic end-product for fuel production using cyanobacteria if high-yielding strains can be developed.
authors.affiliation: Department of Biochemistry and Food Chemistry, University of Turku, Tykistökatu 6A, 6krs, 20520 Turku, Finland.
authors.forename: Jari
authors.initials: J
authors.lastname: Kämäräinen
authors.forename: Henning
authors.initials: H
authors.lastname: Knoop
authors.forename: Natalie J
authors.initials: NJ
authors.lastname: Stanford
authors.forename: Fernando
authors.initials: F
authors.lastname: Guerrero
authors.forename: M Kalim
authors.initials: MK
authors.lastname: Akhtar
authors.forename: Eva-Mari
authors.initials: EM
authors.lastname: Aro
authors.forename: Ralf
authors.initials: R
authors.lastname: Steuer
authors.forename: Patrik R
authors.initials: PR
authors.lastname: Jones
mesh_terms: D000438:Alcohols / Q000378:metabolism; D000473:Alkanes / Q000378:metabolism*; D056804:Biofuels; D002264:Carboxylic Acids / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D046940:Synechococcus / Q000378:metabolism / Q000502:physiology*; D046939:Synechocystis / Q000378:metabolism / Q000502:physiology*
chemical_list: D000438:Alcohols; D000473:Alkanes; D056804:Biofuels; D002264:Carboxylic Acids