(Picture from Martek Annual Report)
Oil Crops Algal Fermentation Process
Cow Stomach “Extractor”
Cull Potatoes
Omega-3 food
Biodiesel
Crude Glycerol
Feed additives to fish
Omega-3 Algal cells before shifting
Algal biomass enriched with
lipids
Waste WaterNutraceuticals and foods
with omega-3
(Picture from www.wikipedia.com)
FeedstocksCull Potato Underutilized agricultural biomass with low commercial
value
Can provide both carbon and nitrogen sources for algae’s growth
Biodiesel Waste Glycerol Negative value by-product of biodiesel industry
Difficult to be purified, due to many impurities
However, it’s good carbon source for algae’s growth
Converting them to high value DHA could provide a great potential market for them
The Health Benefit of DHA (C22:6, -3) Component of the photoreceptor cells of infant retinas
Involved in the development of infant brains
Supplemental DHA in infant formula is strongly recommended by WHO
Reduced risk of age-related neurological disorders, such as Alzheimer’s and dementia
DHA Producing Alga Strain: Schizochytrium limacinum SR21
Heterotrophic algae growing on glucose and glycerol as carbon source
High lipids content in algae biomass (more than 50%)
High ratio of DHA to total fatty acids (more than 30%)
Fast growing
Two-stage Growth of Schizochytrium cell number increasing stage: cell reproduction and rapid cell
number increase with little increase in size and weight of each cell
cell size increasing stage: cells stop reproduction but enlarge due to lipids accumulation
Hypothesis Optimizing culture conditions of these two stages separately
and using a “shifting strategy” will increase the production rate
Omega-3 Used in Aquaculture 1 million tons of fish oil produced globally per year, 70~80%
of it used in aquaculture as fish meal
Aquaculture feed demand increases while ocean fishery resources decline, using fish meal to support aquaculture growth becomes non-sustainable
Organic fish movement requires an omega-3 source that is not originated from fish meal
The omega-3 enriched in the algae biomass produced in this process will be a better source
Potential DHA Market in U.S.
$ ( millions)
Infant Formula 200
Dairy beverages 820
Cheese 500
Beverages (non-dairy) 770
Snacks/candy/cookies/crackers 625
Bread 510
Cereal/Breakfast food 465
Yogurt 70
Other 1,500
Total 5,460
(UBS Global Life Sciences Conference, September 27, 2006)
BACKGROUND
RESULTS1. Verification of the two-stage growth
2. High oxygen concentration culture in the reproduction stage
3. Oxygen consumption in the cell increasing stage 5. Enhancing biomass production with fed batch culture
6. High cell density culture
The cell number stopped increasing after 24 hours, but the dry cell weight kept increasing
The only explanation is that the “body weight” of each cell was increasing
Therefore, to improve biomass production:
1. produce more cells in the first stage
2. grow bigger cells in the second stage
The specific oxygen uptake rate (SOUR) reached its maximum at 8th hr, and decreased to a very low level after 24th hour
Large amount of oxygen was consumed in the cell reproduction stage, but only a little oxygen was consumed in the lipid accumulation stage
Shifting strategy is necessary, in that it produce high cell density at first, and provide optimal condition for lipids accumulation
The bottle neck of the algae biomass production in previous study is low cell density produced in the cell reproduction stage
High oxygen concentration in the reproduction stage produced much more cells
Algae biomass production could be greatly enhanced with this high cell density
4. Biomass production with shift strategy
Culture the cell at high oxygen and nitrogen source concentration at high temperature, then shift the culture to low oxygen and nitrogen concentration at low temperature
Biomass production was greatly enhanced with shift strategy
The cell body weight suppose to be further enhanced, if feed more nutrients in the culture to the high cell density
Shift time(hr)
Dry cell weight (g/L)
cell density(106 cells/ml)
cell body weight(mg/106 cells)
Control (no shifting) 21.5 51 0.42
18 24.6 106 0.23
24 25.3 118 0.21
30 29.3 124 0.24
40 37.9 140 0.27
48 36.2 162 0.22
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To obtain high biomass production with this high cell density culture, more nutrients and carbon source need to be supplemented in the shifted culture, to make the algae cells accumulate more lipids inside cells
With the feeding, the cell body weight was enhanced to 0.38 mg/106 cells, 56 g/L algae biomass was obtained
Culture with 360× 106cells/ml at initial was conducted, 102.4 g/L algae biomass was obtained
DHA Production efficiency was greatly enhanced with this high cell density culture
This process is very promising to be industrialized
ACKNOWLEDGMENTSThis research is supported by the Washington State University
IMPACT Center and the Washington State Potato Commission
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Zhanyou Chi, Yubin Zheng, Chenlin Li, Bo Hu, Shulin ChenZhanyou Chi, Yubin Zheng, Chenlin Li, Bo Hu, Shulin ChenDepartment of Biological Systems Engineering, Washington State University, Pullman, WA 99164-6120Department of Biological Systems Engineering, Washington State University, Pullman, WA 99164-6120
Using wastewater from dark fermentative hydrogen production to culture Oleaginous yeast Cryptococcus curvatus to be used as biodiesel feedstock