Unit IV.B The Prokaryotes (The Gram-Positive Bacteria)

Question 1

• include common soil bacteria, the lactic acid bacteria, and several human pathogens.
  *important endospore-forming bacteria such as the genera Clostridium and Bacillus. Also of extreme importance in medical microbiology are the genera Staphylococcus, Enterococcus, and Streptococcus.

Answer 1

Low G + C gram-positive bacteria (Firmicutes)

Question 2

• include mycobacteria, corynebacteria, and actinomycetes.
• related to gram-positive bacteria because they share common rRNA sequences.

Answer 2

High G + C gram-positive bacteria (Tenericutes)

Question 3

obligate anaerobes; rod-shaped cells contain endospores that usually distend the cell
C. tetani: tetanus
C. botulinum : botulism

Answer 3

Clostridium

Clostridiales

Question 4

• cigar shaped with 80 mm:600 mm in length, can be seen with the unaided eye
• Epulopiscium fishelsoni doesn’t reproduce by binary fission, daughter cells formed within the cell are released through a slit opening in the parent cell.

Answer 4

Epulopiscium

Clostridiales

Question 5

• typically rods that produce endospores, common in soil, and only a few are pathogenic to humans
• Several species produce antibiotics.
  (Bacillus anthracis causes anthrax, a disease of cattle, sheep, and horses that can be transmitted to humans )

Answer 5

Bacillus

Bacillales

Question 6

occur in grapelike clusters
Staphylococcus aureus yellow-pigmented colonies (aureus = golden), facultative anaerobes,can grow in high osmotic pressure and low moisture

Answer 6

Staphylococcus

Bacillales

Question 7

lactic acid–producing bacteria aerotolerant and capable of growth in the presence of oxygen

Answer 7

Lactobacillus

Lactobacillales

Question 8

• spherical, gram-positive bacteria that typically appear in chains
• Pathogenic streptococci produce several extracellular substances that contribute to their pathogenicity.

Answer 8

Streptococcus

Question 9

• adapted to areas of the body that are** rich in nutrients but low in oxygen** → gastrointestinal tract, vagina, and oral cavity.
• found in large numbers in human stool
• persist as contaminants in a hospital environment, on hands, bedding, and even as a fecal aerosol, high resistance to most antibiotics

Answer 9

Enterococcus:

Question 10

Listeria monocytogenes can contaminate food, especially dairy products.
survives within phagocytic cells and is capable of growth at refrigeration temperatures
If it infects a pregnant woman, the organism poses the threat of stillbirth or serious damage to the fetus.

Answer 10

Listeria

Question 11

highly pleomorphic because they lack a cell wall
* smallest self-replicating organisms, ranging from 0.1 to 0.25 μm

Answer 11

Mycoplasma

Question 12

highly pleomorphic in their morphology

Answer 12

Actinobacter (High G + C Gram-Positive Bacteria

Question 13

aerobic, non–endospore forming rods
myco (funguslike) → exhibition of filamentous growth

Answer 13

Mycobacterium

Question 14

2 groups of Mycobacterium:

Answer 14

• slow growers
• fast or rapid growers

Question 15

• coryne (club-shaped), tend to be pleomorphic, and their morphology often varies with the age of the cells
• C. diphtheriae the causative agent of diphtheria

Answer 15

Corynebacterium

Question 16

Ability to form propionic acid; some species are important in the fermentation of Swiss cheese.
* P. acnes are bacteria that are commonly found on human skin and are implicated as the primary bacterial cause of acne.

Answer 16

Propionibacterium

Question 17

• Gardnerella vaginalis is a bacterium that causes one of the most common forms of vaginitis.
• There has always been some difficulty in assigning a taxonomic position in this species, which is gram variable and exhibits a highly pleomorphic morphology.

Answer 17

Gardnerella

Question 18

causes nitrogen-fixing nodules to form in alder tree roots, much as rhizobia cause nodules on the roots of legumes.

Answer 18

Frankia

Actinomycetes

Question 19

• best known of the actinomycetes and most commonly isolated from soil
• produce a gaseous compound called geosmin, which gives fresh soil its typical musty odor
• produce most of our commercial antibiotics

Answer 19

Streptomyces

actinomycetes

Question 20

• facultative anaerobes that are found in the mouth and throat of humans and animals.
• form filaments called hyphae that can fragment
• A. israelii causes actinomycosis, a tissue destroying disease usually affecting the head, neck, or lungs.

Answer 20

actinomyces

Question 21

aerobic and common in soil
* to reproduce, they form rudimentary filaments, which fragment into short rods.
* N. asteroides, cause a chronic, difficult-to-treat pulmonary infection.

Answer 21

Nocardia

Question 22

thrive in salt concentrations of more than 25%, → Great Salt Lake and solar evaporating ponds.

Answer 22

halophiles

Question 23

optimal growth temperature is 80°C or higher.

Answer 23

thermophilic archaea

Question 24

can be found growing at pH values below zero and frequently at elevated temperatures, as well.

Answer 24

Acidophilic archaea

Question 25

oxidize ammonia for energy.

Answer 25

nitrifying archaea

Question 26

strictly anaerobic archaea that produce methane as an end-product by combining hydrogen (H2) with carbon dioxide (CO2).

Answer 26

Methanogens