Life sciences slides about micro organisms.

1. Micro-
organisms
Bacteria and fungi.

2. What are microorganisms?
-Technically a microorganism or microbe is an
organism that is microscopic. The study of
microorganisms is called microbiology.
Microorganisms can be bacteria, fungi, archaea or
protists.

3. bacteria

4. Characteristics of
bacteria.
• Bacteria belong to the Kingdom Monera.
Bacteria are found everywhere on earth.
Some are pathogenic and cause
diseases such as tuberculosis, while
most are useful (Alstrom, 2001).
• Bacteria are unicellular (one celled)
organisms. bacteria can be seen using a
light microscope (Alstrom, 2001).
• Bacteria are distinguished from one
another by their shape. These shapes
include: coccus – round, bacillus – rod-
shaped, spirillum – spiralshaped, and
vibrio – comma-shaped (Alstrom, 2001).

5. Shapes of the bacteria

6. Bacteria's structural
characteristics
All bacteria have the following structural characteristics :
• A cell wall made up of polysaccharides.
• Some bacteria have a slime capsule to protect them from
drying out.
• Cytoplasm surrounded by a cell membrane.
• No membrane-bound organelles.
• The DNA is in the form of an irregular loop and is called a
nucleoid.
• Since there is no membrane around the nuclear material,
bacteria are said to be prokaryotic.
• A plasmid, small, circular, double-stranded DNA molecule is
also found in the cytoplasm of bacteria.
• Many bacteria have a whip-like flagellum which they can use
to move in a liquid. The flagella can rotate to propel the
organism forwards.

7. Structure of the bacteria cell

8. Nutrition and reproduction of bacteria
• Autotrophic bacteria can manufacture their own food.
• Photosynthetic bacteria use sunlight energy, while Chemosynthetic bacteria get their energy
from chemical processes (Blanc et al., 2006).
• Heterotrophic bacteria cannot manufacture their own food. This includes:
• Parasitic bacteria that obtain their food from other living organisms (Blanc et al., 2006).
• Saprotrophic bacteria that play an important role as decomposers. They obtain their food from dead
organic plants and animals.
• Mutualistic bacteria that form a relationship with another organism.
• Both organisms benefit from the relationship (Blanc et al., 2006).
• Bacteria reproduce by the process called binary fission.

9. fungi

10. Characteristics of
fungi
• The Kingdom Fungi includes moulds, yeasts, mildews, rusts, toadstools
and mushrooms (Marshall & Alexander, 1960).
• Fungi have the following characteristic in common:
• Some are unicellular (yeasts) while others are multicellular (mushrooms).
• Eukaryotic (i.e. have a nuclear membrane).
• Heterotrophic since they lack chlorophyll.
• Fungi that live off dead organic matter are said to be saprotrophic.
• Parasitic fungi live off living organisms (Marshall & Alexander, 1960).

11. Structure of a fungi

12. Fungi Characteristics
conti....
• Cell walls which contain chitin. Plants have
cellulose in their cell walls.
• The bodies of multicellular fungi are made up of
threads called hyphae. All the hyphae together
form a mycelium (Marshall & Alexander, 1960).
• The hyphae are often multinucleate (have
many nuclei). Fungi reproduce both sexually
and asexually (Marshall & Alexander, 1960).
• Asexual reproduction in unicellular fungi such
as yeasts is by budding.
• In multicellular fungi asexual reproduction is by
means of spores.

13. References
• Alstrom, S. (2001). Characteristics of Bacteria from
Oilseed Rape in Relation to their Biocontrol Activity
against Verticillium dahliae. Journal of
Phytopathology, 149(2), 57–64.
https://doi.org/10.1046/j.1439-0434.2001.00585.x
• Blanc, C., Sy, M., Djigal, D., Brauman, A., Normand, P.,
& Villenave, C. (2006). Nutrition on bacteria
by bacterial-feeding nematodes and consequences
on the structure of soil bacterial community. European
Journal of Soil Biology, 42, S70–S78.
https://doi.org/10.1016/j.ejsobi.2006.06.003
• Marshall, K. C., & Alexander, M. (1960). GROWTH
CHARACTERISTICS OF FUNGI AND
ACTINOMYCETES. Journal of Bacteriology, 80(3),
412–416. https://doi.org/10.1128/jb.80.3.412-416.1960