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Genomics of microalgae, fuel for the future?

Brooijmans RJ, Siezen RJ - Microb Biotechnol (2010)

View Article: PubMed Central - PubMed

Affiliation: B-Basic, 2628 BC Delft, the Netherlands.

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First‐ and second‐generation biofuels envision the conversion of plant biomass via the action of microorganisms, into usable organic compounds (alcohols and fats) and hydrogen... In general, microalgae do not comprise an evolutionarily related group, and may refer to cyanobacteria (blue‐green algae) or eukaryotic algae... Furthermore, algae can be grown everywhere where there is plenty of water and sun (including lakes or in the sea) and thus are not necessarily restricted to (or compete with) areas with arable land... Combined with their fast growth rate, microalgae are considered one of the few realistic sources for the production of biofuels and superior to agricultural crop‐derived bioethanol... Nevertheless, the two major classes of diatoms are represented: the bi/multipolar centrics (Thalassiosira pseudonana) and the pennates (Phaeodactylum tricornutum)... About 57% of the genes found in P. tricornutum have homologues in T. pseudonana and both have acquired a remarkable number of bacterial genes (after secondary endosymbiosis), a degree of magnitude higher than found in other free living eukaryotes... These include genes encoding silicic acid transporters, many spermidine and spermine synthase‐like enzymes, silaffins and frustulins (casing glycoproteins)... Up to fourfold more genes putatively encoding spermidine and spermine synthases can be found in diatom genomes than in other organisms... Chitin fibres, extending from the silica cage, are thought to limit sinking and can account for up to 40% of the biomass... Many diatom‐specific cyclins were also found in the genomes of P. tricornutum and T. pseudonana... For all its beauty, the actual function of the silica shell remains somewhat unclear... It may reduce predation by grazers... In addition to growing diatoms as algae for biofuels, the discovery of the genes that are associated with the silica cage formation may provide handles for future manipulation of the silica nanostructure to catalyse nanobiotechnological applications... Despite the growing number of completed microalgae genome sequences, only a few examples of genetic engineering of the metabolism for the production of biofuels are reported... The immediate future for metabolic engineering with microalgae may lie in the (over)production of high‐value chemicals or biomass components.

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Production of potential biofuels with photosynthetic cyanobacteria. Schematic representation of the metabolism underlying ‘photofermentation’, based on the introduction of a fermentation pathway or a hydrogen evolution pathway (i.e. a hydrogenase) from a chemotrophic organism into a cyanobacterium. Coupling between the endogenous metabolism of the phototrophic organism and the (heterologously encoded) pathways may occur through central metabolites like glyceraldehyde‐3‐phosphate or NADPH (and ATP). Reproduced from Angermayr and colleagues (2009) with permission from Elsevier.
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f3: Production of potential biofuels with photosynthetic cyanobacteria. Schematic representation of the metabolism underlying ‘photofermentation’, based on the introduction of a fermentation pathway or a hydrogen evolution pathway (i.e. a hydrogenase) from a chemotrophic organism into a cyanobacterium. Coupling between the endogenous metabolism of the phototrophic organism and the (heterologously encoded) pathways may occur through central metabolites like glyceraldehyde‐3‐phosphate or NADPH (and ATP). Reproduced from Angermayr and colleagues (2009) with permission from Elsevier.

Mentions: Cyanobacteria have proven to be a rich source for (toxic) bioactive metabolites, many of which are lipopeptides that display antibacterial, antifungal, antialgal, antiprotozoan and even antiviral activity (Rastogi and Sinha, 2009). Some produce polyhydroxyalkanoates (PHAs) as carbon storage compound, a potential precursor for biodegradable plastics. Furthermore, N2‐fixating cyanobacteria may be useful as natural fertilizers to stimulate (marine) bioremediation efforts (Abed et al., 2009). In terms of biofuels, the production of hydrogen gas with cyanobacteria, which is released in some conditions as metabolic by‐product, has been given most scientific attention (Fig. 3). There are at least three enzymes directly involved in hydrogen production: the nitrogenase, the uptake hydrogenase (associated with N2fixation encoded by hupSL) and the bidirectional hydrogenase (hoxEFUYH) involved in fermentation and/or photosynthesis. The latter two hydrogenases (NiFe hydrogenases) and the nitrogenase are not present in all cyanobacterial species (Tamagnini et al., 2007; Allahverdiyeva et al., 2010). Mutation of hupL, normally involved in removal of H2produced by the nitrogenase, led to increased hydrogen production in Nostoc punctiforme ATCC29133 and Anabaena sp. PCC7120 (Lindberg et al., 2002; Masukawa et al., 2002).


Genomics of microalgae, fuel for the future?

Brooijmans RJ, Siezen RJ - Microb Biotechnol (2010)

Production of potential biofuels with photosynthetic cyanobacteria. Schematic representation of the metabolism underlying ‘photofermentation’, based on the introduction of a fermentation pathway or a hydrogen evolution pathway (i.e. a hydrogenase) from a chemotrophic organism into a cyanobacterium. Coupling between the endogenous metabolism of the phototrophic organism and the (heterologously encoded) pathways may occur through central metabolites like glyceraldehyde‐3‐phosphate or NADPH (and ATP). Reproduced from Angermayr and colleagues (2009) with permission from Elsevier.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3815765&req=5

f3: Production of potential biofuels with photosynthetic cyanobacteria. Schematic representation of the metabolism underlying ‘photofermentation’, based on the introduction of a fermentation pathway or a hydrogen evolution pathway (i.e. a hydrogenase) from a chemotrophic organism into a cyanobacterium. Coupling between the endogenous metabolism of the phototrophic organism and the (heterologously encoded) pathways may occur through central metabolites like glyceraldehyde‐3‐phosphate or NADPH (and ATP). Reproduced from Angermayr and colleagues (2009) with permission from Elsevier.
Mentions: Cyanobacteria have proven to be a rich source for (toxic) bioactive metabolites, many of which are lipopeptides that display antibacterial, antifungal, antialgal, antiprotozoan and even antiviral activity (Rastogi and Sinha, 2009). Some produce polyhydroxyalkanoates (PHAs) as carbon storage compound, a potential precursor for biodegradable plastics. Furthermore, N2‐fixating cyanobacteria may be useful as natural fertilizers to stimulate (marine) bioremediation efforts (Abed et al., 2009). In terms of biofuels, the production of hydrogen gas with cyanobacteria, which is released in some conditions as metabolic by‐product, has been given most scientific attention (Fig. 3). There are at least three enzymes directly involved in hydrogen production: the nitrogenase, the uptake hydrogenase (associated with N2fixation encoded by hupSL) and the bidirectional hydrogenase (hoxEFUYH) involved in fermentation and/or photosynthesis. The latter two hydrogenases (NiFe hydrogenases) and the nitrogenase are not present in all cyanobacterial species (Tamagnini et al., 2007; Allahverdiyeva et al., 2010). Mutation of hupL, normally involved in removal of H2produced by the nitrogenase, led to increased hydrogen production in Nostoc punctiforme ATCC29133 and Anabaena sp. PCC7120 (Lindberg et al., 2002; Masukawa et al., 2002).

View Article: PubMed Central - PubMed

Affiliation: B-Basic, 2628 BC Delft, the Netherlands.

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

First‐ and second‐generation biofuels envision the conversion of plant biomass via the action of microorganisms, into usable organic compounds (alcohols and fats) and hydrogen... In general, microalgae do not comprise an evolutionarily related group, and may refer to cyanobacteria (blue‐green algae) or eukaryotic algae... Furthermore, algae can be grown everywhere where there is plenty of water and sun (including lakes or in the sea) and thus are not necessarily restricted to (or compete with) areas with arable land... Combined with their fast growth rate, microalgae are considered one of the few realistic sources for the production of biofuels and superior to agricultural crop‐derived bioethanol... Nevertheless, the two major classes of diatoms are represented: the bi/multipolar centrics (Thalassiosira pseudonana) and the pennates (Phaeodactylum tricornutum)... About 57% of the genes found in P. tricornutum have homologues in T. pseudonana and both have acquired a remarkable number of bacterial genes (after secondary endosymbiosis), a degree of magnitude higher than found in other free living eukaryotes... These include genes encoding silicic acid transporters, many spermidine and spermine synthase‐like enzymes, silaffins and frustulins (casing glycoproteins)... Up to fourfold more genes putatively encoding spermidine and spermine synthases can be found in diatom genomes than in other organisms... Chitin fibres, extending from the silica cage, are thought to limit sinking and can account for up to 40% of the biomass... Many diatom‐specific cyclins were also found in the genomes of P. tricornutum and T. pseudonana... For all its beauty, the actual function of the silica shell remains somewhat unclear... It may reduce predation by grazers... In addition to growing diatoms as algae for biofuels, the discovery of the genes that are associated with the silica cage formation may provide handles for future manipulation of the silica nanostructure to catalyse nanobiotechnological applications... Despite the growing number of completed microalgae genome sequences, only a few examples of genetic engineering of the metabolism for the production of biofuels are reported... The immediate future for metabolic engineering with microalgae may lie in the (over)production of high‐value chemicals or biomass components.

Show MeSH