Targeted expression of nuclear transgenes in Chlamydomonas reinhardtii with a versatile, modular vector toolkit

Lauersen KJ, Kruse O, Mussgnug JH. Targeted expression of nuclear transgenes in Chlamydomonas reinhardtii with a versatile, modular vector toolkit. Applied Microbiology and Biotechnology. 2015;99(8):3491-3503

Reconstruction of the lipid metabolism for the microalga Monoraphidium neglectum from its genome sequence reveals characteristics suitable for biofuel production

Bogen C, Al-Dilaimi A, Albersmeier A, et al. Reconstruction of the lipid metabolism for the microalga Monoraphidium neglectum from its genome sequence reveals characteristics suitable for biofuel production. BMC Genomics. 2013;14(1): 926.BACKGROUND: Microalgae are gaining importance as sustainable production hosts in the fields of biotechnology and bioenergy. A robust biomass accumulating strainof the genus Monoraphidium (SAG 48.87) was investigated in this work as apotential feedstock for biofuel production. The genome was sequenced, annotated, and key enzymes for triacylglycerol formation were elucidated. RESULTS: Monoraphidium neglectum was identified as an oleaginous species with favourable growth characteristics as well as a high potential for crude oil production, based on neutral lipid contents of approximately 21% (dry weight) under nitrogen starvation, composed of predominantly C18:1 and C16:0 fatty acids. Further characterization revealed growth in a relatively wide pH range and salt concentrations of up to 1.0% NaCl, in which the cells exhibited larger structures. This first full genome sequencing of a member of the Selenastraceae revealed a diploid, approximately 68 Mbp genome with a G + C content of 64.7%. The circular chloroplast genome was assembled to a 135,362 bp single contig, containing 67 protein-coding genes. The assembly of the mitochondrial genome resulted in two contigs with an approximate total size of 94 kb, the largest known mitochondrial genome within algae. 16,761 protein-coding genes were assigned to the nuclear genome. Comparison of gene sets with respect to functional categories revealed a higher gene number assigned to the category "carbohydrate metabolic process" and in "fatty acid biosynthetic process" in M. neglectum when compared to Chlamydomonas reinhardtii and Nannochloropsis gaditana, indicating a higher metabolic diversity for applications in carbohydrate conversions of biotechnological relevance. CONCLUSIONS: The genome of M. neglectum, as well as the metabolic reconstruction of crucial lipid pathways, provides new insights into the diversity of the lipid metabolism in microalgae. The results of this work provide a platform to encourage the development of this strain for biotechnological applications and production concepts

Efficient phototrophic production of a high-value sesquiterpenoid from the eukaryotic microalga Chlamydomonas reinhardtii

Lauersen KJ, Baier T, Wichmann J, et al. Efficient phototrophic production of a high-value sesquiterpenoid from the eukaryotic microalga Chlamydomonas reinhardtii. Metabolic Engineering. 2016;38:331-343

Investigating the dynamics of recombinant protein secretion from a microalgal host

Lauersen KJ, Huber I, Wichmann J, et al. Investigating the dynamics of recombinant protein secretion from a microalgal host. Journal of Biotechnology. 2015;215:62-71

Biomethanation potential of biological and other wastes

Anaerobic technology has been traditionally applied for the treatment of carbon rich wastewater and organic residues. Anaerobic processes can be fully integrated in the biobased economy concept for resource recovery. After a brief introduction about applications of anaerobic processes to industrial wastewater treatment, agriculture feedstock and organic fraction of municipal solid waste, the position of anaerobic processes in biorefinery concepts is presented. Integration of anaerobic digestion with these processes can help in the maximisation of the economic value of the biomass used, while reducing the waste streams produced and mitigating greenhouse gases emissions. Besides the integration of biogas in the existing full-scale bioethanol and biodiesel production processes, the potential applications of biogas in the second generation lignocellulosic, algae and syngas-based biorefinery platforms are discussed.(undefined

Efficient recombinant protein production and secretion from nuclear transgenes in Chlamydomonas reinhardtii

Lauersen KJ, Berger H, Mussgnug JH, Kruse O. Efficient recombinant protein production and secretion from nuclear transgenes in Chlamydomonas reinhardtii. Journal of Biotechnology. 2013;167(2):101-110.Microalgae are diverse photosynthetic microbes which offer the potential for production of a number of high value products (HVP) such as pigments, oils, and bio-active compounds. Fast growth rates, ease of photo-autotrophic cultivation, unique metabolic properties and continuing progress in algal transgenics have raised interest in the use of microalgae systems for recombinant protein (RP) production. This work demonstrates the development of an advanced RP production and secretion system for the green unicellular model alga Chlamydomonas reinhardtii. We generated a versatile expression vector that employs the secretion signal of the native extracellular C. reinhardtii carbonic anhydrase for efficient RP secretion into the culture medium. Unique restriction sites were placed between the regulatory elements to allow fast and easy sub-cloning of sequences of interest. Positive transformants can rapidly be identified by high-throughput plate-level screens via a coupled Gaussia luciferase marker. The vector was tested in Chlamydomonas wild type CC-1883 (WT) and in the transgene expression transformant UVM4. Compared to the native secretion signal of the Gaussia luciferase, up to 84% higher RP production could be achieved. With this new expression system we could generate transformants that express up to 10 mg RP per liter culture without further optimization. The target RP is found exclusively in culture medium and can therefore easily be isolated and purified. We conclude that this new expression system will be a valuable tool for many heterologous protein expression applications from C. reinhardtii in the future

Ultrastructure of photosynthesis in green algae mutants

Foo AFW, Hankamer BD, Mussgnug JH, Rupprecht J, Kruse O, McDowall AW. Ultrastructure of photosynthesis in green algae mutants. MICROSCOPY AND MICROANALYSIS. 2007;13(S02):2-3