MICROALGAE CULTURE (2) BIO301 Dr Navid Moheimani Prof Michael - - PowerPoint PPT Presentation

MICROALGAE CULTURE (2)

BIO301 Dr Navid Moheimani Prof Michael Borowitzka

Nutrients

• Macronutrients (g.l-1)
• Micronutrients (mg.l-1)
• Trace Elements (μg.l-1)

Macronutrients

C

CO2, HCO3

• , CO3

2-, organic molecules

O

O2, H2O, organic molecules

H

H2O, organic molecules, H2S

N

N2, NH4

+, NO3

• , NO2
• , amino acids, purines, pyrimidines, urea, etc

Na Several inorganic salts, i.e. NaCl, Na2SO4 K Several inorganic salts, i.e. KC1, K2SO4, K3PO4 Ca Several inorganic salts, i.e. CaCO3, Ca2+ (as chloride) P Several inorganic salts, Na or K phosphates, Na2 glycerophosphate S Several inorganic salts, MgSO4, amino acids Mg Several inorganic salts, CO3

2-, SO4 2- or Cl- salts

Cl As Na+ , K+ , Ca2+, or NH4

• salts

Micronutrients

Fe FeCl3, Fe(NH4)2SO4, ferric citrate Zn SO4

2¯ or Cl¯ salts

Mn SO4

2¯ or Cl- salts

Br As Na+, K+, Ca2+, or NH4

• salts

Si Na5SiO59H2O B H5BO5

Trace Elements

Mo Na+ or NH4

+ molybdate salts

V Na5VO4.16H2O Sr SO4

2-or Cl- salts

Al SO4

2-or Cl- salts

Rb SO4

2- or Cl- salts

Li SO4

2- or Cl- salts

Cu SO4

2- or Cl- salts

Co Vitamin B12, SO4

2- or Cl- salts

I As Na+, K+, Ca2+, or NH4- salts Se Na2SeO3

Inorganic C

CO2 + H2O ⇔ HCO3

• + H+ ⇔ CO3

2- + H+

Note: The pK values are strongly affected by salinity

Organic C {hetrotrophs and/or mixotrophs}

• Main form used by algae is acetate

(up to about 1 g.l-1)

• Some can also use glucose
• Other organic C sources – ethanol,

galactose etc.

N

• The usual nitrogen sources in algal media are (1)

nitrate; (2) ammonium; or (3) urea

• The heterocystous blue-green algae

(cyanobacteria), can also fix atmospheric N2.

• Most algae can use nitrate (NO3
• ), nitrite (NO2
• ) or

ammonium (NH4

+) as an N source

• Urea (NH2)CO is also potentially a good nitrogen

source for almost all algal species. Urea is hydrolysed before its N is incorporated into the algal cells by the action of either the enzyme urease, or the enzyme urea amidolyase (UALase).

Ammonia & Ammonium

NH4

+ NH3 + H+

pKa in FW at 20oC = 9.23

Dunaliella salina cultures. ( = 1 g.l-1 KNO3; • = 1 g.l-1 NH4NO3; O = 0.5 g.l-1 NH4NO3 (a) growth (b) carotenogenesis KNO3 NH4NO3 1 g.l-1 0.5 g.l-1 KNO3 NH4NO3

P

• The major form in which algae take up

phosphorous is as inorganic phosphate (H2PO4

• and HPO4

2-)

• Uptake is optimum at alkaline pH
• Can also use organic P compounds
• High concentrations of P may be toxic!
• Luxury phosphate uptake

S, Ca, Mg, Na, Cl

• Required by all algae to some degree
• Ca:Mg ratio generally more important than actual concentrations

Si

• Most (all?) algae have a low Si

requirement

• Diatoms have high Si requirement (added

as H4SiO4 (silicic acid)

• Germanium if added at a molar ratio of

Ge/Si of 0.1 to 0.2 inhibits diatom growth

Fe

• Essential for ALL algae
• Needs to be added in chelated form (i.e.

FeCl2 with EDTA or citrate) to be able to be take up

• High concentrations are toxic!

Other bits & Pieces

• Vitamins (mainly B12 and other B series)
• Selenium

O2

• Algae require O2 (but some can survive

periods of anoxia)

• High O2 will inhibit photosynthesis

(photorespiration)

• Competes as substrate for Ribulose,bis-

phosphate carboxylase/oxygenase

Isolating Algae

• Enrichment Culture
• Serial Dilution
• Single cell isolation
• ‘streaking’ on agar plates and colony selection
• Density Centrifugation
• The ‘spray’ method