Project description:Unicellular marine algae have promise for providing sustainable and scalable biofuel feedstocks, although no single species has emerged as a preferred organism. Moreover, adequate molecular and genetic resources prerequisite for the rational engineering of marine algal feedstocks are lacking for most candidate species. Heterokonts of the genus Nannochloropsis naturally have high cellular oil content and are already in use for industrial production of high value lipid products. First success in applying reverse genetics makes Nannochloropsis species attractive models to investigate the cell and molecular biology and biochemistry of this fascinating organism group. (Principle findings) Here we present the assembly of the 28.7 Mb genome of Nannochloropsis oceanica CCMP1779. RNA sequencing data from N-replete and N-depleted growth conditions support a total of 11,973 genes, which in addition to automatic annotation were manually inspected to predict the biochemical repertoire for this organism. Among others, more than 100 genes putatively related to lipid metabolism, 114 predicted transcription factors and 109 transcriptional regulators were annotated. In addition, we provide protocols for the transformation of the sequenced strain. (Significance) The availability of genomic and transcriptomic data for Nannochloropsis oceanica CCMP1779, along with efficient transformation protocols provides a blueprint for future detailed gene functional analysis and phylogenetic comparison of Nannochloropsis species by a growing academic community focused on this genus. one sample each of nitrogen-replete and nitrogen-depleted conditions
Project description:Dunaliella salina Bardawil (also known as Dunaliella bardawil) is an extremophilic, unicellular green alga from the Chlorophyte lineage. D. salina is found in hypersaline environments where it can tolerate extremes of heat, light, pH, and up to saturating concentrations of salt. The D. salina Bardawil isolate (UTEX LB 2538) was found in a salt pond near the Bardawil Lagoon on the Sinai peninsula in 1976. This isolate of D. salina is the richest natural source of beta-carotene, a highly valuable commercial product. This accession includes an RNA-Seq analysis of D. salina Bardawil cultures grown in iron-replete (1.5 µM) or iron-deficient (0 µM) media.
Project description:Limited systems-level understanding of oil synthesis in wild oleaginous algae has hindered the development of microalgal feedstock. Nannochloropsis is a small unicellular microalgae widely distributed in oceans and fresh water. In many large-scale and pilot-scale outdoor cultivation facilities, Nannochloropsis strains have been found to be capable of robust growth when supplied with flue gases, naturally accumulating large quantities of oils in a stationary phase, and exhibiting resistance to environmental contaminants. The rich genomic resources, compact genomes, resistance to foreign DNA invasion, wide ecological adaptation, large collections of natural strains and the demonstrated ability to grow on a large scale suggested Nannochloropsis can serve as research models and platform strains for economical and scalable photosynthetic production of fuels and chemicals. To untangle the intricate genome-wide networks underlying the robust biomass accumulation and oil production in Nannochloropsis, we applied high-throughput mRNA-sequencing and reconstructed the structure and dynamics of the genome-wide functional network underlying robust microalgal triacylglycerol (TAG) production in Nannochloropsis oceanica, by tracking the genome-wide, single-base-resolutiontranscript change for the complete time-courses of nitrogen-depletion-induced TAG synthesis. Nannochloropsis oceanica IMET1 cells were grown in liquid cultures under continuous light (approximately 50 M-BM-5mol photons m-2 s-1) at 25M-bM-^DM-^C and aerated by bubbling with a mixture of 1.5% CO2 in air. Mid-logarithmic phase algal cells were collected and washed three times with axenic seawater. Equal numbers of cells were re-inoculated in nitrogen replete medium (Control condition or C, i.e. N+) and nitrogen deprived medium (N deficiency or N, i.e. N-) with 50M-BM-5mol m-2 s-1 light intensity, respectively. Cell aliquots were collected for RNA isolation after being transferred to the designated conditions for 3h, 4h, 6h, 12h, 24h and 48h. Three biological replicates of algal cultures were established under each of the above M-bM-^@M-^\CM-bM-^@M-^] (i.e. N+) and M-bM-^@M-^\NM-bM-^@M-^] (i.e. N-) conditions, respectively. In total, 36 samples collected at six time points (3h,4h,6h,12h,24h and 48h) were used for mRNA-Seq library preparation and then submitted to Illumina HiSeq 2000 for sequencing.
Project description:We set out to investigate the genetic adaptions of the known marine fungus Paradendryphiella salina CBS112865 to the degradation of brown macro-algae, expecting to find a repertoire of carbohydrate active enzymes highly specialized to the degradation of algal polysaccharides. We performed whole genome, transcriptome sequencing and shotgun proteomic analysis of the secretome of P. salina growing on three species of brown algae and under carbon starvation. The genome comparison to close terrestrial fungal relatives, revealed P. salina to have a similar, but reduced carbohydrate active enzyme (CAZyme) profile, except for the presence of three putative alginate lyase 7 genes, most likely acquired via ancient horizontal gene transfer event from a marine bacterium and a polysaccharide lyase 8 gene with similarity to ascomycete chondroitin AC lyases. The proteomic analysis revealed both PL7 and PL8 enzymes to be highly abundant in the algal fermentations together with enzymes necessary for degradation of laminarin, cellulose, lipids and peptides. Our findings indicate that the base CAZyme repertoire of saprobic and plant pathogenic ascomycetes with the necessary addition of alginate lyases provide the fungi with the enzymatic capabilities to thrive on brown algae polysaccharides and even cope with the algal defense mechanisms.