Algae are a diverse group of photosynthetic organisms that can exist as single-celled or multicellular forms. They are found in a variety of habitats from oceans to freshwater and even snow. Algae play important roles in ecosystems and have many uses including producing oxygen, forming the base of the aquatic food chain, and providing products for food, medicine, and biofuels.

1. MICROBIOLOGY
ALGAE

2. CONTENTS
• INTRODUCTION
• CHARACTERISTICS OF ALGAE
• TYPES OF ALGAE
• EXAMPLES OF ALGAE
• USES AND IMPORTANCE OF ALGAE

3. INTRODUCTION
Algae can exist as single cells, an example of which is
Chlamydomonas, or joined together in chains like
Spirogyra or made up of many cells, for instance
Rhodymenia (red seaweed).
Most algae live in fresh or sea water where they can either
be free-floating (planktonic) or attached to the bottom.
Some algae can grow on rocks, soil or vegetation as long
as there is enough moisture. A few algae form very close
partnerships with fungi to form lichens. Unusual algal
habitats are the hairs of the South American sloth and
polar bears.

4. They vary from small, single-celled forms to complex
multicellular forms, such as the giant kelps of the eastern
Pacific that grow to more than 60 meters in length and form
dense marine forests. Algae are found in the fossil record
dating back to approximately 3 billion years in the
Precambrian.
All algae contain a pigment called chlorophyll a (other types of
chlorophyll such as b, c and/or d may also be present) and
they make their own food by photosynthesis. The chlorophyll
is contained in the chloroplasts and gives many algae their
green appearance. However some algae appear brown, yellow
or red because in addition to chlorophylls they have other
accessory pigments that camouflage the green colour.

5. Algae play many important and beneficial roles in fresh water
environments. They produce oxygen and consume carbon
dioxide, act as the base for the aquatic food chain, remove
nutrients and pollutants from water, and stabilize
sediments. Excessive algal growths, however, can cause
detrimental effects on aquatic systems, endangering the
organisms that live in or depend on these systems and
hampering or preventing human uses of the infested
waterways.

6. Algae exist in environments ranging from oceans, rivers, and lakes
to ponds, brackish waters and even snow. Algae are usually green,
but they can be found in a variety of different colours. For instance,
algae living in snow contain carotenoid pigments in addition to
chlorophyll, hence giving the surrounding snow a distinctive red
hue.
● Algae are autotrophs, having chloroplasts, they can
manufacture their food through photosynthesis.
● They reproduce by simple cell division or spores
● Unicellular algae are in a variety of shapes, such as rods,
spherical, spindle, etc. Multicellular algae are ribbon like
filaments with or without branches.

7. ● Algae are neither bacteria nor
plants. The term algae is used
to describe a large collection of
photosynthetic, eukaryotic
organisms.
Unlike traditional plants, algae
do not have true roots, stems
and leaves. Hence, they need to
be near a moist or watery
environment to survive. In
other words, they do not
possess vascular tissue
necessary for the conduction of
water and minerals.

8. CHARACTERISTICS OF ALGAE
Algal cells are eukaryotic. Algae can photosynthesize like plants, and they possess
specialized structures and cell-organelles, like centrioles and flagella, found only in
animals. The algal cell walls consist of mannans, cellulose and Galatians. Listed below
are some of the general characteristics of algae.
 Algae are photosynthetic organisms
 Algae can be either unicellular or multicellular organisms
 Algae lack a well-defined body, so, structures like roots, stems or leaves are
absent
 Alga are found where there is adequate moisture.
 Reproduction in algae occurs in both asexual and sexual forms. Asexual
reproduction occurs by spore formation.
 Algae are free-living, although some can form a symbiotic relationship with
other organisms.

9. TYPES OF ALGAE
RED ALGAE BROWN ALGAE
RHODOPHYTA PHAEOPHYTA
GREEN ALGAE
CHOLOPHYTA

10. RED ALGAE
Also called Rhodophyta, it is a
distinctive species found in
marine as well as freshwater
ecosystems. The pigments
phycocyanin and
phycoerythrin are responsible
for the characteristic red
colouration of the algae.
Other pigments that provide
green colouration (such as
chlorophyll a) are present.
However, they lack
chlorophyll b or beta-
carotene.

11. GREEN ALGAE
It is a large, informal grouping of algae having the primary
photosynthetic pigments chlorophyll a and b, along
with auxiliary pigments such as xanthophylls and beta
carotene.
Higher organisms use green algae to conduct
photosynthesis for them. Other species of green algae
have a symbiotic relationship with other organisms.
Members are unicellular, multicellular, colonial and
flagellates. Prominent examples of green algae
include Spirogyra, Ulothrix, Volvox, etc.
Multicellular examples of algae include the giant kelp and brown algae. Unicellular
examples include diatoms, Euglenophyta and Dinoflagellates.

12. BROWN ALGAE
Brown algae are algal species characterized
by being multicellular and having a brown or
greenish-brown color. The color is due to the
predominance of brown pigments, e.g.
fucoxanthin, in addition to the green
(chlorophyll a and c). Many of them are
macroscopic. In fact, kelps are large brown
seaweeds that grow in shallow oceans and
form the so-called kelp forest. Fucus is
macroscopic brown algal species. They thrive
in intertidal zones of rocky seashores. They
harvested, dried, and processed for the
commercial production of soap, glass, etc.
They are also used as fertilizers.

13. ULOTHRIX FUCUS
PHORPYRA
EXAMPLES
SPIROGYRA

14. USE AND IMPORTANCE OF ALGAE
Algae are known to fix 50% carbon dioxide. Being
photosynthetic, they increase the oxygen content of their
environment. They are primary producers and many organisms
derive food from them. Many commercial products are
obtained from algae such as align, etc.
Algae form the primary source of food for many organisms in
the food chain. From an economical perspective, algae are
very useful for creating biomass or fertilizers as they grow very
fast

15. USE AND IMPORTANCE OF ALGAE
Algae are important as primary producers of organic matter at
the base of the food chain. They also provide oxygen for other
aquatic life. Algae may contribute to mass mortality of other
organisms, in cases of algal blooms, but they also contribute to
economic well- being in the form of food, medicine and other
products. In tropical regions, coralline algae can be as
important as corals in the formation of reefs.

16. ALGAL BIOFUEL
Recent developments in science and technology have enabled algae to be
used as a source of fuel. Global demand for petroleum products and declining
environmental health have prompted the use of eco-friendly alternatives such
as algal biofuel. Hence, algae fuel is an increasingly viable alternative to
traditional fossil fuels. It is used to produce everything from “green” diesel to
“green” jet fuel. It is similar to the other biofuels made from corn and sugar
cane.

17. THANK YOU
AREN MAE P. RESGUARDO, LPT
HAZEL MANOLO, LPT
DONDY MARANGGA, LPT
MAYBELYN PANUNCIAR, LPT
CLARK COGONON, LPT
RHEA TINGAL, LPT
STEFANIE VILLARUEL, LPT