ORNL is managed by UT-Battelle for the US Department of Energy

Algae: Fuel for the future? Teresa Mathews Environmental Sciences Division

2 Presentation_name

Why should you care about algae? • Diverse, aquatic, ancient, photosynthetic (and beautiful!)

Red Algae

Green Algae

Diatoms

Blue green algae

3 Presentation_name

Why should you care about algae? • Diverse, aquatic, ancient, photosynthetic (and beautiful!)

• Important for global cycles of carbon dioxide, oxygen, nitrogen, etc.

4 Presentation_name

Why should you care about algae? • Diverse, aquatic, ancient, photosynthetic (and beautiful!)

• Important globally for biogeochemical cycles of carbon, nitrogen, oxygen

• ~40% of net primary productivity globally—important source of food!

Try some day! Spirulina, Chlorella

5 Presentation_name

Why should you care about algae? • Diverse, aquatic, ancient, photosynthetic (and beautiful!)

• Important globally for biogeochemical cycles of carbon, nitrogen, oxygen

• ~40% of net primary productivity globally—important source of food!

• Water quality issues (e.g. harmful algal blooms, “dead zones”)

6 Presentation_name

Why does the Department of Energy care about algae?

7 Presentation_name

Georgiana et al., Nature, 2012

energy.agwired.com Why does the Department of Energy care about algae?

Land area required to replace 100% of U.S. petroleum needs with biodiesel

Lipid productivity much higher than

other energy crops Short

generation time Captures CO2 and can

grow in wastewater

8 Presentation_name

Challenges for algal biofuel commercialization Cost (2500-5000 gallons biofuel intermediate/acre/year @ $3/GGE) -Increasing biomass and lipid productivity Crop protection: minimizing algae death from grazers or pests Limiting resources: - Water supply - Nutrients demands (N, P, CO2)

Improve economics through using wastewater.

Heathy pond

Crashed pond

www.laprogressive.com

Pond crash due to pest (adapted from Sapphire Energy Inc., CA)

9 Presentation_name

Cyanotech Corporation, Hawaii

Algal biomass production: Monoculture vs polyculture

Specialist pathogen

www.waterontheweb.org Seasonal succession of phytoplankton populations

In nature, algae exist in polycultures

Biofuel industry focus is on growing monoculture

Polycultures can provide crop

protection against specialist pests

10 Presentation_name

Does increased species diversity lead to increased productivity?

Shurin et al., 2014

Overyielding can occur if polycultures include species with complementary traits or that occupy different niches

11 Presentation_name

Creating niche differentiation with nutrients

• 106 C: 16 N: 1 P – Nitrate (NO3) – Ammonia (NH4) – Urea (NH2)2CO

• How do algal growth rates differ when given different nitrogen sources?

• Do different algal species prefer different nitrogen sources?

• Can polycultures grown in mixed nutrient media outperform monocultures?

Culture media

Waste water

12 Presentation_name

Outcome: Decreased cost and increased

annual biomass yield

Complementarity can reduce competition among species for

nitrogen.

Our hypothesis: Algal polycultures in wastewater produce

more biomass Ammonium uptake (9 mol/L/day)

Tetraselmis Chlamydomonas

Navicula

Raphidocelis

Scenedesmus

Urea uptake (3 mol/L/day)

Nitrate uptake (5 mol/L/day)

Algal species showed complementarity in forms of nitrogen use

13 Presentation_name

Polyculture

Monoculture NO3

media

NH4 media

Urea media

NO3+NH4+urea media

(simulated wastewater)

16 algal species communities

Experimental design

1-species cultures: 5

2-species cultures: 10

5-species culture: 1

4 media (all containing

equimolar nitrogen) Algae cultures

in lab

14 Presentation_name

Overyielding (polyculture yield – monoculture mean) occurs most often in wastewater media

Biomass yield: Monocultures vs polycultures

128 82 161 0

30

60

90

120

150

180

B E BE

Bio

mas

s (m

g/L)

Positive overyielding polycultures

56 Monoculture mean = 105

128 112 93 0

30

60

90

120

150

180

B C BC

Bio

mas

s (m

g/L)

Negative overyielding polycultures

-27

Monoculture mean = 120

Spe

cies

co

mbi

natio

n

Over yielding = polyculture yield – mean of mono cultures

15 Presentation_name

The rate of increase in biomass production

is highest in wastewater with polycultures

Biomass production vs species richness

300

200

100

0

Bio

mas

s (m

g/L)

1 2 3 4 5 Species richness

Nitrate

Wastewater simulated

Urea

Ammonium

0

10

20

30

Slop

e

16 Presentation_name

NUE =Biomass

Nitrogen in biomass

Nutrients use efficiency (NUE) is much more

pronounced in wastewater with polycultures

30

20

NU

E (b

iom

ass/

N)

0 1 2 3 4 5

Species richness

Nutrients use efficiency (NUE) vs species richness

Nitrate

Wastewater simulated

Urea

Ammonium

0

1

2

3

Slop

e

17 Presentation_name

What mechanisms are responsible for over yielding?

Ammonium Nitrate Urea Wastewater A B AB AB

Complementary effect

Selection effect

Over yielding= Complementary + Selection effect

Bio

dive

rsity

effe

ct µ

m3 /m

L

Overyielding in wastewater was mostly explained by

complementary effect

18 Presentation_name

We see promising

evidence of increased

productivity in algal

polycultures, especially with

wastewater

Polyculture in wastewater

can reduce the nutrients cost

by increasing nutrients use

efficiency

Next steps: Feasibility study to

use wastewater resources in US.

Crop protection

using algal polycultures

Conclusions and future direction

19 Presentation_name

Questions?

20 Presentation_name

Extra slides

21 Presentation_name

Can GM algae survive outdoor settings and express engineered

phenotypes?

How far would GM algae disperse?

What risks do GM algae pose to native ecosystems?

Acutodesmus dimorphus

Addition of 2 genes: • C14 fatty acid biosynthesis • Green fluorescence protein (GFP)

Genetic modification of Acutodesmus dimorphus

First EPA-approved GM algae in open ponds

Genetically modified (GM) algae: Realizing the potential and weighing the risk

Dispersal tank

22 Presentation_name

GM phenotypes translated from lab to field

Wild type

GM

Alga

l bi

omas

s (g

/L)

GM pond

Wild type

Harvest 1

Harvest 2

Harvest 3

3-fold increase of C14:0 fatty

acids in GM strain

GM pond performed similar to wild type

GFP expressed in both lab and field

23 Presentation_name

-10 0 10 20 30 40 50

-10

010

2030

4050

4226 34

34

21

59

3259

y

>

>

Distance: P=0.0003 Distance* direction: P=0.004

Dispersal in different directions

GM algae can disperse with no apparent effect on native algae

Mur

ray

Mira

mar

Pow

ay

indo

ante

e

ControlWTGM

Lake Murry Miramar Poway Lindo Santee N

umbe

r of a

lgal

spe

cies

5

10

15

0

ContrWTGM

Colonization in natural water bodies without effect on native algae composition

Dis

tanc

e no

rth (m

)

Frequency of counts by wind direction (%)

W

S

N

E 2%

6% 10%

14% 18%

22%

mean = 0.681 calm = 15.8%

0 to 1 1 to 2 2 to 3 (m/s)

Frequency of counts by wind direction (%)

Distance east (m)

A- days to invasions

Increasing productivity