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Microbes
• Are invisible to the naked eye, you need a powerful microscope to see them.
• Are everywhere around us, inside us, on us, in our food, in our homes, in the air we breathe and the water we wash in.
• Are mostly useful, but some are harmful
• Have been around for 3.8 bn years.
• Are vital for life on Earth.
What do Microbes look like ?
Magnified 1000’s of times and coloured using dye, we see -
Microbes exist in huge numbers
In one single teaspoon of garden soil, there are over 100,000 microbes. In 1ltr of seawater, there are over 1bn microbes.
On your hands there are more microbes than there are people in the world.
There are so many microbes, that scientists have only named 0.5% of them.
Microbes outnumber all other species and make up most of the living matter on the planet.
Microbes – three types
• Bacteria strep bacteria
• Virus rotavirus
• Fungi mould
Bacteria
• Have three main shapes
• Bacteria are prokaryotic and unicellular.
• Bacteria have cell walls.
• Bacteria have circular DNA called plasmids
• Bacteria can be anaerobes or aerobes.
• Bacteria are heterotrophs or autotrophs.
• Bacteria are awesome!
BACTERIA
Endospore
• Bacteria can survive unfavorable conditions by producing an endospore.
• Depending on the species, bacteria can be aerobic which means they require oxygen to live
or
• anaerobic which means oxygen is deadly to them.
Green patches are green sulfur
bacteria. The rust patches are colonies
of purple non sulfur bacteria. The red
patches are purple sulfur bacteria.
METHANOGENS
These Archebacteria are anaerobes. They make methane (natural gas) as a waste product. They are found in swamp sediments, sewage, and in buried landfills. In the future, they could be used to produce methane as a byproduct of sewage treatment or landfill operation.
EXTREME HALOPHILES
can live in extremely salty environments.
Most are photosynthetic autotrophs.
The photosynthesizers in this category are
purple because instead of using chlorophyll
to photosynthesize, they use a similar
pigment called bacteriorhodopsin that
uses all light except for purple light, making
the cells appear purple.
the Great Salt Lake of Utah or salt ponds
on the edge of San Francisco Bay
From hot springs and other high temperature environments. Some can grow above the boiling temperature of water. They are anaerobes, performing anaerobic respiration.
Thermophiles are interesting because they contain genes for heat-stable enzymes that may be of great value in industry and medicine
THERMOPHILES
• Those that are classified as autotrophs are either photosynthetic, obtaining energy from sunlight or chemosynthetic, breaking down inorganic substances for energy .
Bacteria can be autotrophs or heterotrophs.
Cyanobacteria
• You may have seen them as "green slime" in your aquarium or in a pond.
• can do "modern photosynthesis", which is the kind that makes oxygen from water.
• the first organisms on Earth to do modern photosynthesis and they made the first oxygen in the Earth's atmosphere.
What can bacteria do ?
We have learnt that bacteria do many good things,
- such as decompose waste
- give texture and flavour to food.
- They give off oxygen when they ‘eat’. Half of all the oxygen in the world, comes from bacteria.
Bacteria that cause Diseases
DISEASE Bacteria
BOTULISM Clostridium botulinum
CHOLERA Vibrio cholerae
DIARRHEA (Traveller's Diarrhea ) Escherichia coli
FOOD POISONING Salmonella enteritidis
LEPROSY (Hansen’s Disease) Mycobacterium leprae
PEPTIC ULCER Helicobacter pylori
PNEUMONIA Streptococcus pneumoniae
TETANUS Clostridium tetani
TBERCULOSIS Mycobacterium tuberculosis
TYPHOID FEVER Salmonella typhi
FUNGI
• Eukaryotic
• Nonphotosynthetic
(heterotrophic)
• Most are multicellular
• Most are microscopic molds or yeasts
The study of fungi is
known as MYCOLOGY.
Fungi
Not just mushrooms –
athlete’s foot, penicillin, and yeast.
Yeast is used in bread making,
and brewing
Structure of Fungi
• Filaments of fungi are called hyphae.
• The cell walls contain chitin.
• The MYCELIUM is a mat of hyphae visible to the unaided eye ( bread mold)
• Some hyphae may divided by cross sections called septa
Septated
Unseptated - coenocytic
Penicillin, an antibiotic, comes from molds of the
genus Penicillium Notice the area of inhibition
around the Penicillium.
DISEASE Fungi
CANDIDIASIS (Infection of mouth and vagina) Candida
MENINGITIS (Severe form of infalammation of the membranes
covering the brains and the spinal cord)
Cryptococcus neoformans
PNEUMOCYSTIS (a form of pneumonia) Pneumocystis jiroveci
HISTOPLASMOSIS (A FORM OF LUNG INFECTION) Histoplasma capsulatum
ASPERGILLOSIS (Infection of the lungs and other organs of the body) Aspergillus
RINGWORM Tinea Corporis
ATHLETE’s FOOT Tinea Pedis
DANDRUFF Pityrosporum ovale
DISEASE-CAUSING FUNGI
VIRUSCome in 1000s of different shapes and sizes.
They hang about waiting to meet a ‘host’ which
they then invade, hijacking the host’s cells.
Beware the air you breathe and door handles !
viruses
– with only DNA/RNA + protein coat
– all are parasitic (they are considered living
only when they are inside living cells) they
cannot produce their own food
• A virus is another microorganism that caused diseases.
• A virus is even smaller than bacteria. It must use a living cell to grow and reproduce.
DISEASE Virus
ACQUIRED IMMUNODEFICIENCY SYNDROME (AIDS) Human immunodeficiency Virus (HIV)
CHICKENPOX Varicella Zoster Virus
COMMON COLD Enterovirus
INFLUENZA (FLU) Influenza virus
GASTROENTERITIS Norovirus
GANITAL CANCER/ CERVICAL CANCER Human papillomavirus
HEPATITIS A Hepatovirus
POLIOMYELITIS Poliovirus
GERMAN MEASLES Rubella
YELLOW FEVER Flavivirus
What is a virus?
• A virus is another microorganism that caused diseases.
• A virus is even smaller than bacteria. It must use a living cell to grow and reproduce.
• Virus can cause colds.
• Influenza virus • AIDS virus
Different types of viruses
Different Shaped Viruses
Size
• Smaller than bacteria
• 20-300 nanometres (nm)
• A virus contains nucleic acid (DNA or RNA)
• Surrounded by a protective coat (capsid)
Structure of a Virus
Binding With the Host Cell
PROTISTS
• All protists have a nucleus and are thereforeeukaryotic.
• Protists are either plant-like, animal-like or fungus-like.
PROTOZOANS
are animal-like protists (heterotrophs) grouped
according to how they move.
The word protozoa means "little animal." They are
so named because many species behave like tiny
animals—specifically, they hunt and gather other
microbes as food.
All protozoa digest their food in stomach-like
compartments called vacuoles <vac-you-ohls>.
AMOEBA
The first group is amoebae <ah-
me-bee>,
1. testate amoebae, which have a
shell-like covering,
2. naked amoebae, which don't
have this covering.
Amoebae ooze along by means of
pseudopodia (false feet) engulfing
food as they go.
• The second group is the Flagellates<flah-geh-lets>, are generally the smallest of the protozoa and have one or several long,
• whip-like projections called flagellapoking out of their cells.
• Flagellates use their flagella to move.
• It is a flagellate in the intestines of termites which enable them to eat wood. Both organisms benefit…..what kind of relationship do they have?
FLAGELLATES
• The third group of protozoans are the ciliates from the phylum Ciliophora. These are generally the largest protozoa.
• They are covered with hair-like projections called cilia and they eat the other two types of protozoa as well as bacteria.
• Ciliates are found in every aquatic habitat.
CILIATES
• The last of the Protozoans are Sporozoa.
• These are heterotrophic, parasitic and nonmotile.
• For example is plasmodium vivax.
SPOROZOANS
• Plant-like protists are autotrophs – they contain chloroplasts and make their own food.
• Algae are eukaryotic autotrophs.
• They produce much of Earth’s oxygen.
ALGAE and PHYPTOPLANKTONS
• are both plant-like and animal-like.
• Euglena are autotrophs since they make food from sunlight and
• Heterotrophs since they ingest food from surrounding water.
EUGLENA
• are photosynthetic autotrophs with yellow and brown pigments.
• They have shells of silica.
• They make up a large portion of the world’s phytoplankton which is Earth’s largest provider of oxygen.
DIATOMS
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