Symbiotic algae, Measurement of algal growth, Algal strain selection, Cultivation of algae, Biofuel production from algae:

1. Symbiotic algae
Measurement of algal growth
Algal strain selection
Cultivation of algae
Biofuel production form algae:
Dr. Harinatha Reddy M.sc, Ph.D.
biohari14@gmail.com
Department of Microbiology
Sri Krishnadevaraya University
Anantapur, A.p. India

2. Lichens: Symbiotic relationships between fungi and
algae:
 Lichens is a symbiotic association between fungi and various
groups of algae or Cyanobacteria.
 The most characteristic feature of lichens is that the
combination of algae (called the phytobiont) and fungus
(called the mycobiont),

3. Symbiotic Association between Cyanobacteria and sponges and
spoon (echiuroid) worms:
 Echiura, are spoon worms, are a small group of marine
animals.
 Sponges are multicellular parazoan organisms that have
bodies full of pores.

4. Symbiotic relation between Brown-yellow algae (Zooxanthellae) and
marine corals:
 Corals are marine invertebrates
 The algae present inside the marine corals.
 Corals provide protection and waste material to the algae.
 Algae intern provide nutrients and organic molecules to the
coral.

5. Symbiotic Association between Chlorella and Hydra:
 Hydra is a small, fresh-water animals.
 Chlorella is a genus of single-cell green algae belonging to
the division Chlorophyta.

6. Measurement of algal growth

7.  Micro algae cultivated for biofuel production.
 Production of biofertilizer (anabaena and nostoc).
 Spirulina and Chlorella for single cell protein.


8.  Direct methods: are algal biomass, packed cell volume, cell
counts and detecting pigment contents.
 Indirect methods: are changes in chemistry of the aqueous
environment used to express algal growth quantitatively.

9. Measuring turbidity:
 An increasing number of algae cells is supposed to increase
the turbidity of the samples.
 An increase in the turbidity of samples should decrease their
transmittance.

10. Biomass: Counting cells in the sample:
 The number of cells in 1 mL of sample could be defined
using a hemocitometer and a light microscope.
 A hemocitometer is used to count cells in a small amount
of sample.
 It is impossible to count cells, if their number is too big.
Such a sample should be diluted before counting.

11. Carbon content measurements:
 Inorganic carbon (CO2) is the primary nutrient required for
sustainable algal cultivation.
 However, CO2 is dissolved in an aqueous system (water) and
forms a weak acid-base buffer system.
C02+ H2O------------ CO3
- + 2H+
pH change:
Therefore, bicarbonate (HCO- 3) is the dominant inorganic
species in the pH where most microalgae thrive (i.e., between pH
8 and 10).

12. Algal strain selection

13. Algal species used for biofuel, protein and starch
production need the following properties:
 Produces high and constant lipid, protein and starch content.
 High photosynthetic efficiency.
 Grows with seasonal climatic differences and daily changes
in temperatures and pH.
 Easy to harvest.
 Easy to extract lipids, proteins and starch from algal cells.

14.  Microalgae one of the most promising biofuel feed stocks,
because of their:
 High lipid protein and starch productivity,
 High photosynthetic efficiency,
 High rapid growth rates.

15.  Microalgae or Microphytes are microscopic algae
typically found in freshwater and marine systems.
 They are unicellular species which exist individually, or in
chains or groups

16. Some algae are high in protein and others are mostly
starches or lipids.
Algae Lipids Proteins Carbohydrates
Anabaena 4-7 43-56 25-30
Chlorella 64-72 5-20 16-23
Spirulina 4-6 46-63 8-14
Spirogyra sp. 11-21 6-20 33-64
Table 1. Composition of Various Algae (% of dry matter)

17. Large scale cultivation of algae

18.  Commercial and industrial algae cultivation has numerous uses,
including production of food ingredients such as:
 Fatty acids
 Starch
 Protein
*********
 Bio fertilizers
 Bio plastics,
 Biofuel,
 Wastewater treatment
 Pollution control.

19.  Algae are organisms that grow in aquatic environments and use
light and carbon dioxide (CO2) to create biomass.
 There are two classifications of algae: microalgae and
macroalgae.
 Microalgae Unicellular algae (phytoplankton, microphytes).
 Macroalgae, multi-cellular algae commonly known as seaweed.

20. Algae cultivation can be achieved in two ways:
1. Photobioreactors (PBR) and
2. Open ponds
 A photobioreactor is a closed system, which provides a
controlled environment (T.m.p, pH, CO2 and Water) and
enables high productivity of algae.

21.  Tubular photobioreactors.
 Plate photobioreactor
 Horizontal photobioreactor
 Foil photobioreactor

22. Advantages of Photobioreactors:
 Cultivation of algae is in controlled circumstances (T.m.p
and pH), hence potential for much higher productivity.
 It provide large surface volume for photosynthesis.
 Reduction in evaporation of growth medium.
 Better protection from outside contamination.
 Space saving - Can be mounted vertically, horizontally or at
an angle, indoors or outdoors.

23. Open pond Systems :
 The ponds (open system) in which the algae are cultivated are
usually what are called the “raceway ponds”.
 In these ponds, the algae, water & nutrients circulate around a
racetrack.

24. Advantages:
 The biggest advantage of these open ponds is their simplicity.
 Low production costs and
 Low operating costs.
Disadvantages:
 Low productivity.
 The poor light utilization by the cells,
 Evaporation of media,
 Diffusion of CO2 to the atmosphere,
 Requirement of large areas of land.
 Contamination from strains of bacteria or other outside organisms.

25. Nutritional requirement and factors for algal growth:
 Water, carbon dioxide, minerals and light are all important
factors in cultivation.
 Nutrients such as nitrogen (N), phosphorus (P), and
potassium (K) serve as fertilizer for algae, and are generally
necessary for growth.
 Optimum pH of the water is 7.6 to 9.2 and temperature is
15˚C and 35˚C.

26. Biofuel production form algae:

27.  Microalgae good sources for biofuel production because of
their relatively high oil content and rapid biomass
production.
 Microalgae grow very quickly compared to other algae.
 Oils present in microalgae is in the form of tricylglycerols.
Fig: 1Tricylglycerol.

28. Microalga
Oil content
(% dry weight)
Botryococcus braunii 25-75
Chlorella sp. 64-72
Crypthecodinium cohnii 20-27
Cylindrotheca sp. 16-37
Nitzschia sp. 45-47
Phaeodactylum tricornutum 20-30
Schizochytrium sp. 50-77
Tetraselmis suecia 15-23
Table 1. Oil content of microalgae.

29. Advantages:
 Biodiesel is biodegradable, less CO2 emissions.
 Microalgae grow very quickly compared to terrestrial crops.
 Oil content of microalgae is usually between 20 % and 50 %
in dry weight of cell.

30. Oil extraction from microalgae: (Physical and chemical methods)
Physical extraction:
 The simplest method is mechanical crushing. When algae is
dried it retains its oil content, which then can be "pressed" out
with an oil press.
 Osmotic shock: is a sudden reduction in osmotic pressure, this
can cause cells in a solution to rupture. Osmotic shock is
sometimes used to release cellular components, such as oil.

31. Chemical extraction:
 Chemical solvents are often used in the extraction of the oils.
 Solvent such as hexane or petroleum ether, benzene
generally used for oil extraction from algae.
 Enzymatic extraction uses enzymes to degrade the cell walls,
especially cellulase enzyme used to degrade the cell of
algae.

32. Transesterification:
 Algal oil is converted into biodiesel through a
transesterification process.
 Oil extracted from the algae is mixed with alcohol and an
acid or a base to produce Glycerol and methylesters that
makes up the biodiesel. (1 molecule of glycerol and 3
molecules of biodiesel).