Joint bioprospection campaigns from the Arctic, the sub-tropics and Chilean desert
Hans Kleivdal,WP2 Leader, Uni Research
The joint WP2 bioprospecting campaigns have identified promising novel microalgae strains with industrial potential, so far have been collected 244 environmental samples from diverse climatological conditions. An industrial selection criteria was used for the screening of 46 novel clonal strains. Five with high target productivity were identified and require further characterization. In parallel, identical reactor systems are being established by each partner and productivity optimization by metabolic modelling approaches are continuing.
The objectives of WP2 are to perform bioprospecting and selection of robust, highly productive algal species from extreme and diverse climatological conditions. Based on industrial needs, the new strains will be screened for appropriate product profiles and biomass characteristics and productivity parameters will be optimized by metabolic modelling. The aim is to enable cultivation of microalgae in areas with limited potential for agriculture in order to broaden the resource base of a growing microalgae industry.
Task 2.1 Bioprospecting campaigns and screening for novel production strains
The MIRACLES project defined a need to identify strains that are more robust and have higher yields to unlock the full industrial potential of microalgae. One of the main focuses of MIRACLES is on bioprospecting these new, robust and productive algal isolates to evaluate their industrial potential.
Existing microalgae strain collections from the partners in Norway, Gran Canarias and Chile, with a total of 627 strains with widely diverse functional properties, forms the initial bioprospecting resource base for the project. However, WP2 partners have extended the MIRACLES resource base by establishing a 3-year harmonized sampling program from extreme microalgae habitats in highly diverse climatological conditions (Arctic waters, Nordic fjords, sub-tropical islands, altiplanic desert and hot springs). The sampling pursues a rational approach by designing the sampling efforts based on the requests from the industry partners in WP4 and is taking into consideration how evolutionary pressure in extreme habitats (high/low temperatures, high/low irradiation, high saline conditions, aridity etc.) may have developed special strain properties needed for survival. The industrial partners in the MIRACLES project have provided a list of target compounds and functionalities with commercial potential within four market application areas: algae ingredients in food, aquafeed, biobased materials and specialty compounds.
Based on the industrial needs, a set of strain selection criteria was established by the WP2 partners and specific screening procedures were developed for all the target groups. The sampling and screening procedures and plans are implemented in an overall screening program where all the efforts are coordinated to explore the commercial potential of microalgae diversity with industrial guidance. Since implementation in May 2014, a total of 244 environmental samples have been collected of which 86 clonal strains have been established for cultivation. The partners in Norway, Gran Canarias and Chile have so far screened 46 novel strains and identified 5 highly productive strains which may have industrial potential. These will be further assessed using lab-scale reactor systems and the biomass will be evaluated by WP3 and WP4.
Task 2.2 Establish outdoor cultivation systems to evaluate climatic impact on productivity
In order to evaluate productivity potential in different climatic conditions, identical outdoor photobioreactor systems are being installed at the partner locations in Norway, Gran Canarias and Chile. The WP2 members have put considerable effort into defining the specific requirements for the outdoor cultivation system and ensuring suitability for inter-comparison studies. Based on the evaluation of several reactor systems, the GWP-III system of F & M (Italy) was chosen to be the most robust, cost-efficient and suitable system within the economic possibilities. The installation of all three systems is to take place in the period from May to September 2015, and will represent a unique possibility to compare hard productivity data of identical reference strains cultivated in identical reactor systems under different climatic conditions. The first inter-comparison exercise starts in Q3 2015.
Task 2.3 Metabolic modelling to maximize product yields
Efforts are also being made to gain knowledge on how to optimize productivity through metabolic modelling with two different approaches. An experimental approach studied the cultivation of Nannochloropsis gaditana to compare the effect of two different nitrogen sources (NaNO3 and NH4Cl) on fatty acid accumulation during nitrogen-replete and -deplete growth. The analysis showed no significant productivity differences between the different nitrogen sources, however, during nitrogen starvation the dry weight continued to increase four-fold, 50% of which could be explained by the increase in fatty acids. A second approach gathers transcriptomic data from sampling N. gaditana cultures in large-scale outdoor photobioreactors in order to learn about differentially expressed key genes through the production cycle. Furthermore, a re-annotation of the available Nannochloropsis gaditana transcriptomes on databases was performed using different bioinformatics tools. Putative genes involved in the main metabolic pathways have been identified and primer pairs have been designed for a set of genes to study the differential expression of key genes throughout production cycles. The combined data will contribute to improving the metabolic model and how the metabolic flux can be optimized either by metabolic engineering or by cultivation conditions.