Author
Peter G. Kroth
Other affiliations: University of Düsseldorf
Bio: Peter G. Kroth is an academic researcher from University of Konstanz. The author has contributed to research in topics: Phaeodactylum tricornutum & Plastid. The author has an hindex of 40, co-authored 108 publications receiving 7034 citations. Previous affiliations of Peter G. Kroth include University of Düsseldorf.
Papers published on a yearly basis
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École Normale Supérieure1, J. Craig Venter Institute2, Joint Genome Institute3, Alfred Wegener Institute for Polar and Marine Research4, University of Konstanz5, University of Wisconsin–Milwaukee6, University of Melbourne7, University of Washington8, University of Nantes9, University of Wisconsin-Madison10, Ghent University11, University of Rhode Island12, Sewanee: The University of the South13, University of Arizona14, Hebrew University of Jerusalem15, Georgia Institute of Technology16, Leibniz Institute for Neurobiology17, Stazione Zoologica Anton Dohrn18, University of British Columbia19, Stanford University20, Scottish Association for Marine Science21, University of North Carolina at Wilmington22
TL;DR: Analysis of molecular divergence compared with yeasts and metazoans reveals rapid rates of gene diversification in diatoms, and documents the presence of hundreds of genes from bacteria, likely to provide novel possibilities for metabolite management and for perception of environmental signals.
Abstract: Diatoms are photosynthetic secondary endosymbionts found throughout marine and freshwater environments, and are believed to be responsible for around one- fifth of the primary productivity on Earth(1,2). The genome sequence of the marine centric diatom Thalassiosira pseudonana was recently reported, revealing a wealth of information about diatom biology(3-5). Here we report the complete genome sequence of the pennate diatom Phaeodactylum tricornutum and compare it with that of T. pseudonana to clarify evolutionary origins, functional significance and ubiquity of these features throughout diatoms. In spite of the fact that the pennate and centric lineages have only been diverging for 90 million years, their genome structures are dramatically different and a substantial fraction of genes (similar to 40%) are not shared by these representatives of the two lineages. Analysis of molecular divergence compared with yeasts and metazoans reveals rapid rates of gene diversification in diatoms. Contributing factors include selective gene family expansions, differential losses and gains of genes and introns, and differential mobilization of transposable elements. Most significantly, we document the presence of hundreds of genes from bacteria. More than 300 of these gene transfers are found in both diatoms, attesting to their ancient origins, and many are likely to provide novel possibilities for metabolite management and for perception of environmental signals. These findings go a long way towards explaining the incredible diversity and success of the diatoms in contemporary oceans.
1,500 citations
TL;DR: A detailed synthesis of carbohydrate metabolism in diatoms based on the genome sequences of Thalassiosira pseudonana and Phaeodactylum tricornutum is presented, which provides novel insights into acquisition of dissolved inorganic carbon and primary metabolic pathways of carbon in two different diats, which is of significance for an improved understanding of global carbon cycles.
Abstract: Background
Diatoms are unicellular algae responsible for approximately 20% of global carbon fixation. Their evolution by secondary endocytobiosis resulted in a complex cellular structure and metabolism compared to algae with primary plastids.
408 citations
TL;DR: It is demonstrated that a variety of selectable markers and reporter genes can be expressed in P. tricornutum, enhancing the potential of this organism for exploring basic biological questions and industrial applications.
Abstract: A general purpose transformation vector, designated pPha-T1, was constructed for use with the diatom Phaeodactylum tricornutum Bohlin. This vector harbors the sh ble cassette for primary selection on medium containing the antibiotic zeocin, and a multiple cloning site flanked by the P. tricornutum fcpA promoter. pPha-T1 was used to establish the utility of three selectable marker genes and two reporter genes for P. tricornutum transformation. The nat and sat-1 genes confer resistance to the antibiotic nourseothricin, and nptII confers resistance to G418. Each of these genes was effective as a selectable marker for identifying primary transformants. These markers could also be used for dual selections in combination with the sh ble gene. The reporter genes uidA and gfp were also introduced into P. tricornutum using pPha-T1. Gus expression in some transformants reached 15 μg·μg−1 of total soluble protein and permitted excellent cell staining, while GFP fluorescence was readily visible with standard fluorescence microscopy. The egfp gene, which has optimal codon usage for expression in human cells, was the only version of gfp that produced a strong fluorescent signal in P. tricornutum. The codon bias of the egfp gene is similar to that of P. tricornutum genes. This study suggests that codon usage has a significant effect on the efficient expression of reporter genes in P. tricornutum. The results presented here demonstrate that a variety of selectable markers and reporter genes can be expressed in P. tricornutum, enhancing the potential of this organism for exploring basic biological questions and industrial applications.
365 citations
Dalhousie University1, University of British Columbia2, University of Konstanz3, University of Toronto4, Centre national de la recherche scientifique5, United States Department of Energy6, University of Freiburg7, University of Ostrava8, University of Alberta9, Sewanee: The University of the South10, Academy of Sciences of the Czech Republic11, University of New Brunswick12, University of Washington13, University of Exeter14, Aix-Marseille University15, Science for Life Laboratory16, University of Tsukuba17, American Museum of Natural History18, Natural History Museum19, Monterey Bay Aquarium Research Institute20, University of East Anglia21, University of Canterbury22, San Francisco State University23, Reed College24, National Center for Genome Resources25, University of Melbourne26
TL;DR: The nuclear genomes of the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans are sequenced and extensive genetic and biochemical mosaicism is revealed, with both host- and endosymbiont-derived genes servicing the mitochondrion, the host cell cytosol, the plastid and the remnant endosYmbionT cytOSol of both algae.
Abstract: Cryptophyte and chlorarachniophyte algae are transitional forms in the widespread secondary endosymbiotic acquisition of photosynthesis by engulfment of eukaryotic algae. Unlike most secondary plastid-bearing algae, miniaturized versions of the endosymbiont nuclei (nucleomorphs) persist in cryptophytes and chlorarachniophytes. To determine why, and to address other fundamental questions about eukaryote-eukaryote endosymbiosis, we sequenced the nuclear genomes of the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans. Both genomes have >21,000 protein genes and are intron rich, and B. natans exhibits unprecedented alternative splicing for a single-celled organism. Phylogenomic analyses and subcellular targeting predictions reveal extensive genetic and biochemical mosaicism, with both host- and endosymbiont-derived genes servicing the mitochondrion, the host cell cytosol, the plastid and the remnant endosymbiont cytosol of both algae. Mitochondrion-to-nucleus gene transfer still occurs in both organisms but plastid-to-nucleus and nucleomorph-to-nucleus transfers do not, which explains why a small residue of essential genes remains locked in each nucleomorph.
356 citations
University of East Anglia1, Joint Genome Institute2, Norwich Research Park3, Stazione Zoologica Anton Dohrn4, Scripps Institution of Oceanography5, J. Craig Venter Institute6, Alfred Wegener Institute for Polar and Marine Research7, Université Paris-Saclay8, École Normale Supérieure9, University of Paris10, Leibniz Association11, University of Cologne12, University of Konstanz13, Medical University of South Carolina14, University of Duisburg-Essen15, Leibniz Institute for Neurobiology16, University of Washington17, University of Nevada, Las Vegas18, Monterey Bay Aquarium Research Institute19, University of British Columbia20, University of California, Berkeley21
TL;DR: In this article, the genome evolution of a cold-adapted diatom from the Southern Ocean, Fragilariopsis cylindrus, based on a comparison with temperate diatoms was studied.
Abstract: The Southern Ocean houses a diverse and productive community of organisms. Unicellular eukaryotic diatoms are the main primary producers in this environment, where photosynthesis is limited by low concentrations of dissolved iron and large seasonal fluctuations in light, temperature and the extent of sea ice. How diatoms have adapted to this extreme environment is largely unknown. Here we present insights into the genome evolution of a cold-adapted diatom from the Southern Ocean, Fragilariopsis cylindrus, based on a comparison with temperate diatoms. We find that approximately 24.7 per cent of the diploid F. cylindrus genome consists of genetic loci with alleles that are highly divergent (15.1 megabases of the total genome size of 61.1 megabases). These divergent alleles were differentially expressed across environmental conditions, including darkness, low iron, freezing, elevated temperature and increased CO2. Alleles with the largest ratio of non-synonymous to synonymous nucleotide substitutions also show the most pronounced condition-dependent expression, suggesting a correlation between diversifying selection and allelic differentiation. Divergent alleles may be involved in adaptation to environmental fluctuations in the Southern Ocean.
287 citations
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TL;DR: A review of second generation biodiesel production systems using microalgae can be found in this paper, where the main advantages of second-generation microalgal systems are that they: (1) have a higher photon conversion efficiency (as evidenced by increased biomass yields per hectare): (2) can be harvested batch-wise nearly all-year-round, providing a reliable and continuous supply of oil: (3) can utilize salt and waste water streams, thereby greatly reducing freshwater use: (4) can couple CO2-neutral fuel production with CO2 sequestration: (
Abstract: The use of fossil fuels is now widely accepted as unsustainable due to depleting resources and the accumulation of greenhouse gases in the environment that have already exceeded the “dangerously high” threshold of 450 ppm CO2-e. To achieve environmental and economic sustainability, fuel production processes are required that are not only renewable, but also capable of sequestering atmospheric CO2. Currently, nearly all renewable energy sources (e.g. hydroelectric, solar, wind, tidal, geothermal) target the electricity market, while fuels make up a much larger share of the global energy demand (∼66%). Biofuels are therefore rapidly being developed. Second generation microalgal systems have the advantage that they can produce a wide range of feedstocks for the production of biodiesel, bioethanol, biomethane and biohydrogen. Biodiesel is currently produced from oil synthesized by conventional fuel crops that harvest the sun’s energy and store it as chemical energy. This presents a route for renewable and carbon-neutral fuel production. However, current supplies from oil crops and animal fats account for only approximately 0.3% of the current demand for transport fuels. Increasing biofuel production on arable land could have severe consequences for global food supply. In contrast, producing biodiesel from algae is widely regarded as one of the most efficient ways of generating biofuels and also appears to represent the only current renewable source of oil that could meet the global demand for transport fuels. The main advantages of second generation microalgal systems are that they: (1) Have a higher photon conversion efficiency (as evidenced by increased biomass yields per hectare): (2) Can be harvested batch-wise nearly all-year-round, providing a reliable and continuous supply of oil: (3) Can utilize salt and waste water streams, thereby greatly reducing freshwater use: (4) Can couple CO2-neutral fuel production with CO2 sequestration: (5) Produce non-toxic and highly biodegradable biofuels. Current limitations exist mainly in the harvesting process and in the supply of CO2 for high efficiency production. This review provides a brief overview of second generation biodiesel production systems using microalgae.
2,254 citations
University of Washington1, University of Wisconsin–Milwaukee2, École Normale Supérieure3, University of British Columbia4, University of Wisconsin-Madison5, Princeton University6, Martek Biosciences Corporation7, University of California, Santa Barbara8, University of Melbourne9, University of California, San Diego10, Sandia National Laboratories11, University of California, Santa Cruz12, University of Regensburg13, Oak Ridge National Laboratory14, University of Hull15, Joint Genome Institute16, Academy of Sciences of the Czech Republic17, University of Massachusetts Medical School18, Woods Hole Oceanographic Institution19, Alfred Wegener Institute for Polar and Marine Research20, San Francisco State University21, University of California, Berkeley22
TL;DR: The 34 million-base-pair draft nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand-base pair plastid and 44 thousand base-pair mitochondrial genomes were reported in this article.
Abstract: Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis. They are responsible for approximately 20% of global carbon fixation. We report the 34 million-base pair draft nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand-base pair plastid and 44 thousand-base pair mitochondrial genomes. Sequence and optical restriction mapping revealed 24 diploid nuclear chromosomes. We identified novel genes for silicic acid transport and formation of silica-based cell walls, high-affinity iron uptake, biosynthetic enzymes for several types of polyunsaturated fatty acids, use of a range of nitrogenous compounds, and a complete urea cycle, all attributes that allow diatoms to prosper in aquatic environments.
1,945 citations
TL;DR: Although microalgae are not yet produced at large scale for bulk applications, recent advances—particularly in the methods of systems biology, genetic engineering, and biorefining—present opportunities to develop this process in a sustainable and economical way within the next 10 to 15 years.
Abstract: Microalgae are considered one of the most promising feedstocks for biofuels. The productivity of these photosynthetic microorganisms in converting carbon dioxide into carbon-rich lipids, only a step or two away from biodiesel, greatly exceeds that of agricultural oleaginous crops, without competing for arable land. Worldwide, research and demonstration programs are being carried out to develop the technology needed to expand algal lipid production from a craft to a major industrial process. Although microalgae are not yet produced at large scale for bulk applications, recent advances—particularly in the methods of systems biology, genetic engineering, and biorefining—present opportunities to develop this process in a sustainable and economical way within the next 10 to 15 years.
1,712 citations
TL;DR: There are opportunities to use such sustainable polymers in both high-value areas and in basic applications such as packaging.
Abstract: Renewable resources are used increasingly in the production of polymers. In particular, monomers such as carbon dioxide, terpenes, vegetable oils and carbohydrates can be used as feedstocks for the manufacture of a variety of sustainable materials and products, including elastomers, plastics, hydrogels, flexible electronics, resins, engineering polymers and composites. Efficient catalysis is required to produce monomers, to facilitate selective polymerizations and to enable recycling or upcycling of waste materials. There are opportunities to use such sustainable polymers in both high-value areas and in basic applications such as packaging. Life-cycle assessment can be used to quantify the environmental benefits of sustainable polymers.
1,651 citations