Aquaculture in the high north in times of change - Future Food and Feed from Marine Sources Part 2
- 11:00 FEATURED TALK: Microalgae cell factories on the rise, trick or treat?
Authors: Hans Christian Eilertsen ( UiT The Arctic University of Norway )
The recent years we have witnessed increased focus on industrial mass cultivation and utilization of photoautotrophic microalgae. One conclusion that can be drawn from this is that there is a large diversity in the range of (suggested) products and applications, while unfortunately innovative bioreactor concepts are rather scarce or quite missing. In sum most mass cultivation initiatives must today be considered “pilots” or “well advanced plans”. If mass cultivation of microalgae shall have success, large scale industrial units (> 20 000 tons/year) must, for market reasons, be set up and must be profitable as well as environmental sustainable. Unfortunately such initiatives are, in our opinion, largely lacking from the scene.
One of the main reasons for the lack of progress here is that todays cultivated species have too low photosynthetic efficiencies. This can partly be improved by selection of species that allows for long light depths, i.e. large cells with high optical package effects, this combined with selection for efficient CO2 uptake. Also it is important that the reactor is cheap and favors efficient utilization of photons, and that the water that the algae are cultivated in are devoid of light absorbing dissolved organic material. Further the choice of species to cultivate suffers from the belief that “the safe thing to do is to cultivate the same species utilized by others”, e.g. small well-known green or bluegreen ones! Considering the large species and thereby size and chemical diversity that microalgae represents, this is a pity and a culprit that in many ways hinders further development towards profitable mass cultivation concepts. This can, we mean, be overcome by engaging traditional educated taxonomists and algae physiologist in the selection of species and strains, and encourage closer cooperation between biologists, biochemists and technological competence.
A potential profitable production scenario will here be illustrated with results from a ongoing mass cultivation research project integrated in the production line at the ferrosilicon producer Finnfjord as. The initiative is set up to sequester CO2 and NOx from the factory smoke by cultivation of lipid rich light efficient cold water diatoms, while the diatom biomass will be used as fish feed. Finally it will be focused upon that large biotechnology initiatives utilizing live organisms potentially are, by state environmental authorities, considered as being potential environmental treats, e.g. by release of “alien species”.
- 11:30 Potential of the microalgae Scenedesmus sp. in feed for Atlantic salmon
Authors: Mette Sørensen ( Nord University ); Tharindu N B Herath ( Nord University ); Yangyang Gong ( Nord University ); Mark Huntley ( Duke University ); Zackary Johnson ( Duke University ); Viswanath Kiron ( Nord University )
Availability of high quality protein and lipid ingredients to support future growth of Atlantic salmon farming is a challenge. In recent years, fishmeal and fish oil is to a large extent replaced with plant derived ingredients in feeds for salmonids. Plant ingredients in carnivore fish diets have nutritional limitations and sustainability is also debated. There is an increasing interest in use of novel marine ingredients to supply both lipid and valuable amino acids in feeds for fish. The aim of the present study was to investigate the potential of using the microalgae Scenedesmus sp. in low fishmeal diets for Atlantic salmon.
Three diets were formulated with microalgae Scenedesmus sp. incorporated at 0 (Ctrl), 10% (SCE 10) and 20% (SCE 20) partly replacing fish meal in low fish meal diets. Effect of inclusion level was studied on growth, feed utilization, nutrient digestibility and physical quality of feed. Fish with an initial average weight of 229.1 ± 1.5 g were fed the experimental diets in 6 replicates for 65-days, in a combined growth and digestibility study.
The results showed that fish fed SCE 20 had significantly lower weight gain and specific growth rate and feed intake:gain than those fed Ctrl. Retention of lipid differed among all groups while retention of protein and energy was significantly lower in fish fed SCE 20. Digestibility of dry matter, protein and energy was significantly different among all the three dietary treatments.
In conclusion, Scenedesmus sp. can be used at 10% inclusion in diets for Atlantic salmon without negative effect on growth, nutrient retention and physical quality of feeds.
Acknowledgment: This work was partly funded by project Marine Algae Industrialisation Consortium: Combining biofuel and high-value bioproducts, granted to Duke University by the US Department of Energy (Grant DE-EE0007091).
- 11:45 Heterotrophic microalgae -- the potential for cultivating cold-adapted varieties
Authors: Daniela Morales-Sanchez ( Nord University ); Alfredo Martinez ( Instituto de Biotecnologia ); Christopher Hulatt ( Nord University ); Rene Wijffels ( Wageningen University, AlgaePARC ); Viswanath Kiron ( Nord University )
Algae are photosynthetic organism that can convert CO2 to a variety of compounds that could be used as food, feed, high-value chemicals and biofuels. The growing interest in cultivating microalgae for new bio-based industries in Norway has spurred research interest in identifying algae species suitable for the local climatic conditions. During winter season when the light efficiency is low, the microalgae productivity may be poor. Therefore it is important to consider cultivation of heterotrophic microalgae—which use dark conditions and sugar as carbon and energy sources—as an alternative. In comparison with phototrophic growth, under heterotrophic conditions, growth rates, final cell number, cell mass and lipid content, including DHA and EPA can be significantly increased, depending on the selected strain of microalgae.
We present here the optimization of the cultivation of Neochloris oleoabundans (UTEX 1185), a freshwater edaphic microalga, as a concept for application to cold water microalgae species. As an example of a successful process under heterotrophic conditions, the performance of growing in batch and fed-batch cultures with glucose as the only carbon source was characterized.
Batch and fed-batch cultures were carried out in shake flasks and dark stirred tanks with N. oleoabundans, using a mineral medium and glucose at different concentrations.N.oleoabundans was able to grow using glucose. Batch cultures with an initial glucose concentration of 3 g/L allowed increasing the cell number 3.5-times in comparison with phototrophic cultures. Under these conditions, there was no nutrient limitation and the major cellular component was protein. At high glucose concentration (50 g/L) and nitrogen limitation in batch cultures there was a four-fold increase in dry cell weight (DCW), cell mass productivity was 1.03 gDCW/L/day; and lipid accumulation was enhanced up to 50% of the DCW. Exponentially fed-batch cultures controlling the microalgal growth rate allowed us to optimize the process and obtain the highest cell mass productivity (1.9 gDCW/L/day) and global lipid productivity (1.02 gLIP/L/day) reported to date for N. oleoabundans under phototrophic or heterotrophic conditions.
The experience gained from this study will enable us to develop suitable culture strategies for cold adapted microalgae, to develop them especially as feed sources for the aquaculture industry.
Wednesday 24th January 2018
11:00 - 12:00