Generation of random mutants to improve light-use efficiency of Nannochloropsis gaditana cultures for biofuel production

Abstract

BackgroundThe productivity of an algal culture depends on how efficiently it converts sunlight into biomass and lipids. Wild-type algae in their natural environment evolved to compete for light energy and maximize individual cell growth; however, in a photobioreactor, global productivity should be maximized. Improving light use efficiency is one of the primary aims of algae biotechnological research, and genetic engineering can play a major role in attaining this goal.ResultsIn this work, we generated a collection of Nannochloropsis gaditana mutant strains and screened them for alterations in the photosynthetic apparatus. The selected mutant strains exhibited diverse phenotypes, some of which are potentially beneficial under the specific artificial conditions of a photobioreactor. Particular attention was given to strains showing reduced cellular pigment contents, and further characterization revealed that some of the selected strains exhibited improved photosynthetic activity; in at least one case, this trait corresponded to improved biomass productivity in lab-scale cultures.ConclusionsThis work demonstrates that genetic modification of N. gaditana has the potential to generate strains with improved biomass productivity when cultivated under the artificial conditions of a photobioreactor.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0337-5) contains supplementary material, which is available to authorized users.

RNAi‐based targeted gene knockdown in the model oleaginous microalgae Nannochloropsis oceanica

“…Moreover, the use of RNAi in perturbing gene function and cellular network can offer a higher degree of flexibility and nimbleness than gene disruption, as RNAi targets transcripts (instead of the genome) that are in nature more volatile, diverse and sensitive to environment. Therefore, the RNAi method reported here is a valuable addition to the existing genetic toolbox of Nannochloropsis spp., which includes random insertional mutagenesis (Perin et al ., ), homologous recombination (Kilian et al ., ), gene overexpression (Kang et al ., ) and Cas9‐based genome editing (Wang et al ., ).…”

“…For example, insertional mutagenesis and targeted gene disruption have been reported in a few algae, such as Chlamydomonas reinhardtii (Sodeinde and Kindle, ; Dent et al ., ), Phaeodactylum tricornutum (Daboussi et al ., ), Cyanidioschyzon merolae (Minoda et al ., ) and Nannochloropsis spp. (Kilian et al ., ; Perin et al ., ). However, these tools can be laborious, difficult to replicate in other strains, limited by significant biological constraints, or require extensive screening.…”

Light Remodels Lipid Biosynthesis in Nannochloropsis gaditana by Modulating Carbon Partitioning between Organelles

“…In fluorescence induction kinetics, t 2/3 values were taken as the functional antenna size of PSII. Samples, for F v /F m and ASII determination were dark-adapted for 20 min before measuring (Perin et al, 2015).…”

The potential of quantitative models to improve microalgae photosynthetic efficiency

“…Quantitative description of photosynthetic activity and induction of photo‐regulation in PBR. Prediction of (A) photo‐inhibition level, expressed as fraction of photo‐inhibited PSUs out of the total, (B) NPQ activation, as percentage of its maximal activity, and (C) photosynthetic activity, expressed as oxygen evolution (Perin et al ) for different PBR layers, as function of the PBR depth in centimeters (cm). Predictions come from the model developed in (Perin et al ) and refer to Nannochloropsis cultures with a biomass concentration of 1 g l −1 in cylindric lab PBR with 5 cm diameter exposed to 1500 µmol photons m −2 s −1 .…”