Chapter 11 Characterizing and Classifying Prokaryotes
Case Study - Why we need and use classification methods

I. Classification of Prokaryotes - Only 1% can be grown in a normal lab.

    A. Classified - by cell morphology and arrangement

    B. Classified by Metabolic Characteristics - which often determines their environment, pathogenicity

            1. Anaerobic Chemotrophs - those using inorganic versus organic sources of energy without oxygen e.g. methanobacteria vs Clostridium sp. and Lactobacilli

Image Title Description Categories This patient presented with facial tetany. Note the contraction of the masseter and neck muscles. Tetanus is induced by an exotoxin of the tetanus bacillus (Clostridium tetani), which grows anaerobically at site of injury. Tetanus is characterized by painful muscular contractions, primarily of the masseter, and other large muscles. Musculoskeletal Diseases Gram-Positive Bacterial Infections Clostridium Diseases Tetanus

CASE STUDY

Relating bacterial identification and prokaryotic diversity

This photomicrograph reveals Clostridium perfringens grown in Schaedler’s broth using gram-stain.

Clostridium perfringens is a spore-forming, heat-resistant bacterium that can cause foodborne disease. The spores persist in the environment, and often contaminate raw food materials. These bacteria are found in mammalian feces, and soil.

Gram-Positive Bacteria Gram-Positive Bacterial Infections Clostridium

This strip of API® wells was inoculated with Clostridium perfringens.

The API® system is a standard procedure used to obtain a pure culture. It is then subjected to standard biochemical identification, serological identification, and antibiotic sensitivity testing.

Analytical, Diagnostic and Therapeutic Techniques and Equipment

        2. Photosynthetic autotrophs

        3. Aerobic Bacteria - require oxygen

                a. Obligate aerobes - Micrococcus sp., Mycobacterium sp., Pseudomonas sp.

        4. Facultative anaerobes - prefer to use oxygen but can ferment - Enterobacteriaceae

    C. Special qualities of bacteria

        1. Endospore formation

        2. Binary fission

    D. Modern Classification - using DNA

    E. Archaea - Extremophiles - thermophiles, halophiles

 II. The Ecological Implications of Procaryotic Diversity

    A. Terrestrial Habitats - endospore formers, plant symbionts

    B. Aquatic Habitats - lack of regular nutrients

    C. Parasitic Organisms - Bdellovibrio, Legionella

        D. Ecosystems of Animal habitats

            1. normal flora - Staph. epidermidis

            2. Obligate intracellular parasites - Chlamydia

III. Survey of Bacteria –  A few important and diverse examples

A.     Cyanobacteria - photosynthetic

B.     Clostridia - anaerobic endospore forming GPR

C.     Mycoplasmas - bacteria without a cell wall

D.     Bacillus - aerobic endospore forming GPR

E.      Listeria - GPR

F.      Lactobacilli - GPR

G.     Streptococcus & Enterococcus - GPC in chains, catalase negative

H.     Staphylococcus - GPC in clusters - catalase positive

I.        Corynebacterium - GPR palisade & Chinese letters

J.       Mycobacterium - AFB

K.    Actinomycetes - Fungal-like GPR that branch 

L.      Chlamydia - obligate intracellular bacteria 

M.   Spirochetes - spirilla with stiff cell walls

N.    Bacteroides - obligate anaerobic GNR

        P. Non-fermenters - Pseudomonas sp.

    Next Lecture

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Date last updated 10/11/2007
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