Microbiology

Bacteria, Viruses, Protists, and Fungi

Bacteria

Bacteria are classified into two kingdoms: Eubacteria (true bacteria) and Archaebacteria

(Ancient Bacteria).

Until recently, bacteria were placed into one Kingdom - The Kingdom Monera, hence sometimes bacteria are referred to as Monerans

Bacteria

Bacteria are the MOST NUMEROUS ORGANISMS ON EARTH

Bacteria have evolved into many different forms, and they are now part of nearly every environment on Earth They have been found at the bottom of the

oceanic trenches 9.6 km (6 mi) below the water's surface and in Arctic and Antarctic Regions.

Reactivity with Oxygen

Obligate Aerobes - require oxygen for respiration, need oxygen to grow and survive

Obligate Anaerobes - must avoid oxygen, they will die in its presence

Facultative Anaerobes - can use oxygen when it is available, but can also do without it

Archaebacteria

Archaebacteria tend to live in extreme environments - sometimes they are called "Extremophiles" Halophiles - salt lovers Methanogens - produce methane as a by-product Thermoacidophiles - love hot, acidic

environments

Eubacteria

Classified according to their mode of getting nutrients, mechanism of movement, and their shape

Shape of Bacteria / Naming

Cocci - sphereBacilli - rodsSpirilla - spirals

Diplo - in pairsStaph - in clustersStrep - in chains

Bacteria Morphology

Structures that help bacteria survive in hostile environments capsules (slime layers) - help evade immune system and

adhere to surfaces pili - hairlike projections endospores - bacteria become dormant until conditions

become favorable

Bacteria Morphology

Movement Flagella – one or more tail-like structures

Reactions chemotaxis - response to chemicals phototaxis - response to light magnetotaxis - response to magnetic field

Gram Stain

Gram's Stain is a widely used method of staining bacteria as an aid to their identification. It was originally devised by Hans Christian Joachim Gram, a Danish doctor.

Gram's stain differentiates between two major cell wall types. Gram-Negative: Bacterial species with walls containing

small amounts of peptidoglycan Gram-Positive: Bacteria with walls containing relatively

large amounts of peptidoglycan

Gram Negative – light red or pink color

Gram Positive + dark purple

                                                    

   

Escherichia coli, Salmonella typhi, Vibrio cholerae and Bordetella

pertussis

                                                    

   

Staphylococcus epidermidis, Streptococcus pyogenes, and

Clostridium tetani

 

Bacterial Reproduction

Occurs by binary fission - one cell splits into two cells, offspring are genetically identical to parent

  Bacterial conjugation - a form of

sexual reproduction where bacteria exchange genetic information before dividing, offspring have new genes (and new traits)

Bacterial Reproduction

Transformation - bacteria incorporate genes from dead bacteria

Transduction - viruses insert new genes into bacterial cells. This method is used in biotechnology to create bacteria that produce valuable products such as insulin

Bacterial Transformation

Bacteria and Health Some diseases caused by bacteria:

Tetanus Botulism Syphilis Lyme disease Strep throat Pneumonia Anthrax Necrotizing fasciitis (flesh eating bacteria) Toxic shock syndrome

Treatments Antibiotics & Antiseptic solutions

Antibiotics and Antiseptics Joseph Lister created the first antiseptic,

an acid to spray on tables and instruments before surgery (1860)

The Discovery of Penicillin Alexander Fleming Noticed mold growing on petri dishes Bacteria did not grow where the mold was He isolated the chemical that killed bacteria, but

it was not stable Howard Flory continued the work, later

stabilized the chemical Fleming and Flory received the Nobel Prize in

1945

Viruses

Properties of viruses Possess no membranes, cytoplasm, ribosomes,

or other cellular components Cannot move or grow Can only reproduce inside a host cell Consist of 2 major parts - a protein coat, and

hereditary material (DNA or RNA) Extremely tiny, much smaller than a cell and only

visible with advanced electron microscopes

Viruses and their Hosts

Viruses are specific to their hosts. They can only attack specific cells, and not all

viruses can pass between different species (though some can).

Rabies, for instance, can be passed from animal to human.

HIV is a virus that seems specific to humans.

Viruses and their Hosts

The common cold is a virus that specifically attacks cells of the respiratory track (hence the coughing and sneezing and sniffling). Other viruses attack other types of cells. HIV virus specifically attacks white blood cells.

Influenza Influenza, often called the FLU, is an acute, highly

contagious infection of the respiratory tract which commonly occurs in the winter.

Influenza results from different strains of the influenza virus. This virus has the ability to mutate into different forms. That is why although you were exposed to similar strains in the past, you might not be able to defend yourself against a new one.

Symptoms

Vaccine

Flu Virus

Smallpox Virus Incubation period before symptoms:10-14 days

Symptoms: high fever, headache, backache, and vomiting, rash (pox) on the face and arms that spreads to the trunk

How it would be spreadAerosol or person-to-person, potentially by a terrorist-"martyr." It is highly contagious. However, smallpox victims show clear signs of the disease, and anyone who came in contact with them could be vaccinated post-exposure.

Treatment: There is no current treatment against the smallpox virus. Vaccination given 3-5 days post-exposure can prevent the disease.

Vaccine:Vaccine exists but is currently not recommended for the general public. Stockpiles of vaccine are being increased. No one in the U.S. has been vaccinated since 1972, and people vaccinated before then have likely lost immunity.

Variola (Smallpox) Virus

Smallpox

Streptococcus

Strep throat is an infection caused by group A streptococcus bacteria, and it's very common among kids and teens. The symptoms of strep throat include fever, stomach pain, and red, swollen tonsils.

Strep throat usually requires treatment with antibiotics. With the proper medical care - along with plenty of rest and fluids - your child should be back to school and play within a few days.

Strep Throat

HIV HIV Animation

Human immunodeficiency virus (HIV) is a that can lead to AIDS, a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infection. Previous names for the virus include human T-lymphotropic virus-III (HTLV-III), lymphadenopathy-associated virus (LAV), and AIDS-associated retrovirus (ARV).

Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, pre-ejaculate, or breast milk. Within these bodily fluids, HIV is present as both free virus particles and virus within infected immune cells. The four major routes of transmission are unprotected sex, contaminated needles, breast milk, and transmission from an infected mother to her baby at birth. Screening of blood products for HIV has largely eliminated transmission through blood transfusions or infected blood products in the developed world.

HIV infection in humans is now pandemic. As of January 2006, the UNAIDS and the WHO estimate that AIDS has killed more than 25 million people since it was first recognized on Dec. 1, 1981, making it one of the most destructive pandemics in recorded history.

Related to Viruses

Viroids - even smaller than viruses, consist of RNA strands that lack a protein coat

Prions - infectious agents that are believed to be the cause of Mad Cow Disease, relatively new find and much is not known about them

Bacteriophage - viruses that infect bacteria

Viral Reproduction

Lysogenic (Prophage) Pathway - the virus stays within the cell until certain environmental triggers cause it to enter the lytic cycle

Lytic Pathway - rapid replication of the virus, ending in cell lysis (or death). More phages are released to infect other cells

Lysogenic Cycle

A: Virus attaches to host and injects its nucleic acid

B: Viral nucleic acids and proteins are made C: New virus particles are assembled D: Host cell breaks open and virus particles

are released to infect other cells

Lytic Cycle

Protists

Protists are divided into 3 major categories Plantlike Protists

Photosynthetic algae

Animal-like Protists Heterotrophic called protozoa ("first animal")

Fungus-like Protists resemble fungi absorptive protists slime molds and water molds

Plant-Like Protists

Dinoflagellata - 2 flagella Golden Algae – chrysophyta Green Algae – chlorophyta Brown Algae – phaeophyta Red Algae – rhodophyta Diatoms - major component of plankton

                                                                           

Green Algae (Spyrogyra)

                                   

       

Diatoms

Animal-Like Protists Rhizopoda

move using pseudopods (false feet), ex. ameba, eat by phagocytosis

Foraminifera have a shell, some have photosynthetic algae in the shell

Actinopoda helizoans and radiozoans

Apicomplexa parasitic protists, formerly known as sporozoa, Malaria is caused

by a protist in this group Zooflagellates

have a flagella, member of this group causes African Sleeping Sickness

Ciliophora use cilia to move, live in water, ex. paramecium

                                   

                         

Ameba

                                          

                                 

Paramecium

                                   

        

Radiolarian

Fungus-like Protists

Myxomycota - slime molds, produce spores to reproduce, they grow and eat as a mass

Acrasiomycota - cellular slime molds, solitary but can work together

Oomycota - water molds

Slime Molds

Fungi Characteristics

Habitat Air, food, gardens, and

water Warm temperatures (20-

30°)

Once classified as plants because: Grow anchored in soil Cell walls

Fungi Characteristics Structure

Cell walls – made of chitin

Hyphae Anchor the fungus Invade food source Form reproductive

structures Septa

Divide the hyphae into individual cells

Fungi Types

Saprophytes Decomposers that feed on dead organic material

Mutualists Symbiotic relationship (ex. Algae)

Parasitic fungi Absorb nutrients from hosts

Fungi Adaptations

Role Decompose Earth’s organic wastes

Benefits of increased surface area (hyphae) Nutrient absorption

What would happen if there were no fungi? Huge amounts of waste, dead organisms, and

debris would litter the Earth

Fungi Reproduction

Fragmentation Pieces of hyphae are broken by mycellium and grow

into new mycelia

Budding Asexual reproduction – mitosis occurs and new

individuals pinch off from parent

Fungi Reproduction continued…

Spores (reproductive cells) Spores transported to a favorable location Hypha emerge and begin to grow

Advantages of Spore Reproduction Sporangia protect spores (from drying out) Large number of spores increase germination rate

and increase survival rate

Lichens

Symbiotic relationship between a fungus and an alga or cyanobacteria