Chapter 3

Question 1

The 5 I’s of culturing microbes

Answer 1

1. Inoculation – introduction of a sample into
   a container of media
2. Incubation – under conditions that allow
   growth
3. Isolation – separating one species from
   another
4. Inspection
5. Identification

Question 2

What is a colony?

Answer 2

A growth of a singular species

Question 3

Isolation Techniques

Answer 3

Streak Method
Dilution and Pour plate method
Spreading Method

Question 4

What are the properties of Media?

Answer 4

1. Physical state – liquid, semisolid and solid
2. Chemical composition – synthetic
   (chemically defined) and nonsynthetic
   (complex)
3. Functional type – general purpose,
   enriched, selective, differential, anaerobic,
   transport, assay, enumeration

Question 5

Most common medias

Answer 5

nutrient broth – liquid medium containing beef extract
& peptone
nutrient agar – solid media containing beef extract,
peptone & agar

Question 6

Most commonly used solidifying agent?

Answer 6

Agar

Question 7

Types of media

Answer 7

• Synthetic – contains pure organic & inorganic
  compounds in an exact chemical formula
• Complex or nonsynthetic – contains at least one
  ingredient that is not chemically definable
• General purpose media- grows a broad range of
  microbes, usually nonsynthetic (ex LB, nutrient,
  T-soy)
• Enriched media- contains complex organic
  substances such as blood, serum, hemoglobin or
  special growth factors required by fastidious
  microbes

Question 8

Enriched vs Selective Media

Answer 8

• Selective media- contains one or more
  agents that inhibit growth of some microbes
  and encourage growth of the desired
  microbes
• Differential media – allows growth of
  several types of microbes and displays
  visible differences among desired and
  undesired microbes

Question 9

Misc Media

Answer 9

• Reducing medium – contains a substance
  that absorbs oxygen or slows penetration of
  oxygen into medium; used for growing
  anaerobic bacteria
• Carbohydrate fermentation medium-
  contains sugars that can be fermented,
  converted to acids, and a pH indicator to
  show the reaction; basis for identifying
  bacteria and fungi

Question 10

Incubation, Inspection, and Identification

Answer 10

Incubation, Inspection, and Identification
Incubation – temperature-controlled chamber at appropriate temperature and
atmosphere
– microbe multiplies and produces macroscopically observable growth
Inspection – observation; macroscopic and microscopic
– pure culture – grows only single known species of microorganisms
– mixed cultures – hold two or more identified species or
microorganisms
– contaminated culture – once pure or mixed culture that has unwanted
microbes growing
Identification – macroscopic and microscopic appearance, biochemical tests,
genetic characteristics, immunological testing

Question 11

Disposal of Cultures

Answer 11

Steam Sterilization
Incineration

Question 12

Anton van Leeuwenhoek

Answer 12

1632-1723)
: First person to see individual microorganism at the
magnification of 300 times

Question 13

Bacteria Size

Answer 13

1um-10um