Lecture 2

Question 1

Aerobic bacteria

Answer 1

grow in the presence of free oxygen

Question 2

Anaerobic bacteria

Answer 2

grow in the absence of free oxygen

Question 3

Facultatively anaerobic bacteria

Answer 3

grow in either the absence or presence of free oxygen

Question 4

Microaerophilic bacteria

Answer 4

grow in the presence of minute quantities of free oxygen

Question 5

Aerotolerant anaerobes

Answer 5

tolerate presence of oxygen

Question 6

Heterotrophic bacteria

Answer 6

those bacteria that require an organic carbon source for growth

Question 7

Oligotroph

Answer 7

any organism which can grow in relatively nutrient poor environments

Question 8

Mesophiles

Answer 8

grow best in temperatures between 25º to 40ºC. . Most of the microroganisms on earth belong to the group of mesophiles

Question 9

Xerophiles

Answer 9

live in extreme dry environments

Question 10

Acidophiles

Answer 10

live in acidic environments

Question 11

Thermophiles

Answer 11

live and grow in extremely hot environments that would kill most other microorganisms - Grow best at temperatures between 45º to 60ºC.

Question 12

Alkaliphiles

Answer 12

live in alkaline environments like soda lakes, or alkaline soil

Question 13

Psychrophiles

Answer 13

live and grow better in temperatures that are about - 0 to 20°C

Question 14

Halophiles

Answer 14

live and grow in high saline/salty environments

Question 15

Barophiles

Answer 15

can survive under great pressures

Question 16

Psychrotrophs

Answer 16

live and grow better in temperatures that are about - 0 to 30°C

Question 17

If 1ml of inoculum was placed onto an agar plate and 32 colonies were on a plate of 1/1000 dilution, what would the calculation be. Also what would the calculation be if it was 0.5ml of inoculum, 0.25ml, 0.20ml,0.1ml.

Answer 17

1ml - 32x 10,000

0. 5ml - 32 x 10,000 x 2
1. 25ml - 32 x 10,000 x 4
2. 20ml - 32 x 10,000 x 5
3. 1ml - 32 x 10,000 x 10

Question 18

How is the spread plate method more advantageous that the pour plate method?

Answer 18

Colonies develop on the surface of the agar, better for morphology identification
higher bacterial counts

Question 19

When bacteria multiply into macroscopic, isolated colonies - this is known as..

Answer 19

Colony Forming Units (CFU)

Question 20

List 2 examples of organisms that can not be grown in laboratory mediums. (They must be grown in cultures containing living human/animal cells)

Answer 20

Syphilis and Leprosy

Question 21

Heterotrophs

Answer 21

Organic compounds - Carbon source (other feeders)

Question 22

Autotrophs

Answer 22

Inorganic CO2 - Self Feeders

Question 23

Allows growth of a single or limited type of bacteria based on a unique combination of nutritional or physiological attributes.

Answer 23

Elective enrichment medium

Question 24

Microorganisms that are difficult to culture - they have an elaborate requirement for specific nutrients such as vitamins and other growth promoting substances

Answer 24

Fastidious Heterotrophs

Question 25

Chemical compounds containing mainly carbon, hydrogen, nitrogen, and oxygen All living organisms are made up of

Answer 25

organic compounds

Question 26

2 examples of Inorganic compounds: (lacking the properties characteristic of living organism)

Answer 26

Example "hydrochloric and sulfuric acids"

Question 27

2 major types of nutritional bacteria

Answer 27

Heterotrophs & Autotrophs

Question 28

2 examples of Heterotrophs

Answer 28

Photoheterotrophs, Chemoheterotrophs

Question 29

2 examples of Autotrophs

Answer 29

Photoautotrophs and Chemo Autotrophs

Question 30

2 examples of Autotrophs

Answer 30

Photoautotrophs and Chemoautotrophs

Question 31

Involves the use of inhibitory substances or conditions to suppress or inhibit the growth of most organisms while allowing the growth of the desired organism

Answer 31

Selective enrichment medium

Question 32

3 example question that will help make a proper selection of media and physical conditions?

Answer 32

aerobes or anaerobes? autotrophic and heterotrophic? thermophilic organisms, or more likely to be mesophilic?

Question 33

Nitrocellulose filter of pore size 0.45mm is often used to collect the microorganisms and this technique is called

Answer 33

membrane filtration technique.

Question 34

Two different methods are used for the application of the diluted sample to the growth medium

Answer 34

Spread plate  | Pour plate

Question 35

In the pour plate method aliquots of appropriate sample dilutions are mixed with molten agar to what temperature

Answer 35

45C

Question 36

Agar exists as a liquid at elevated temperatures but solidifies on cooling to

Answer 36

38ºC

Question 37

Does agar supply nutritional value to the medium

Answer 37

No

Question 38

Prepared in the laboratory from materials of precise composition

Answer 38

Synthetic Medium

Question 39

Contains certain reasonably familiar materials but that varies slightly in chemical composition from batch to batch.

Answer 39

Complex Medium

Question 40

Heterotrophic plate counts give an indication of the general ______ of the soil as well as an indication of the general availability of organic nutrients within the soil

Answer 40

Health

Question 41

obtain energy from organic substances

Answer 41

Heterotrophic bacteria

Question 42

Two basic types of media can be used for this heterotrophic plate count analysis.

Answer 42

nutrient rich and  nutrient poor media

Question 43

nutrient agar, peptone yeast extract agar and soil extract agar amended with glucose and peptone. These media contain high concentrations of peptone, yeast, and/or extracts from beef or soil are examples of what kind of media

Answer 43

Nutrient Rich

Question 44

media are often called minimal media and contain as much as 75% less of these ingredients, often with substitutions such as casein, glycerol or gelatin. examples - R2A agar, m-HPC agar, soil extract agar with no amendments.

Answer 44

Nutrient poor

Question 45

It contains ingredients to allow distinction of targeted microorganisms. Lots of different selective agents are used during the target directed isolation of microorganisms e.g., the dye crystal violet inhibits most gram-positive bacteria while allowing the growth of gram-negative bacteria.

Answer 45

Differential medium

Question 46

Growths of most fungi are inhibited during the_________ through the use of antifungal antibiotics

Answer 46

bacterial isolations

Question 47

This is normally done by the addition of antibiotics or dyes, such as Rose Bengal, or by lowering the pH of the medium

Answer 47

fungal isolations

Question 48

1] Periodic transfer to fresh media 2] Preservation of overlaying cultures with mineral oil 3] Preservation of cultures by rapid drying in a frozen state (lyophilization) 4] Storage at very low temperatures Are examples of

Answer 48

Maintenance and preservation of pure cultures

Question 49

Some forms of life such as green plants, can utilize radiant energy and they are called

Answer 49

phototrophs.

Question 50

Forms of life incapable of utilizing radiant energy e.g. animal life rely upon oxidation of chemical compounds for their energy. These are called

Answer 50

chemotrophs

Question 51

Among the phototrophic bacteria there are species, which utilize CO2 as their principal source of carbon, and these are called

Answer 51

Photolithotrophs

Question 52

phototrophic bacteria require an organic compound and are called

Answer 52

Photoorganotrophs.

Question 53

If the bacterial energy derives from oxidation of elemental sulfur and inorganic sulfur compounds these are called

Answer 53

chemolithotrophic bacteria

Question 54

if a mixture of bacteria is inoculated on a blood-agar medium, some of the bacteria may hemolyze (destroy) the red blood cells where others do not. A clear zone around the colony is evidence of

Answer 54

hemolysis. Thus, one can distinguish between hemolytic and non-hemolytic bacteria from growth on the same medium.

Question 55

The temperature of incubation, which allows for most rapid growth during a short period of time (12 to 24h), is known as the

Answer 55

Optimum Growth Temperature

Question 56

Optimum Growth Temperature

Answer 56

6.5 and 7.5

Question 57

Although few bacteria can grow at the extremes of the pH range, for most species the minimum and maximum limits fall somewhere between

Answer 57

pH 4 and pH 9

Question 58

Certain bacteria isolated from brines, salt packs, certain foods, and ocean water called which grow only when the medium contains an unusually high concentration of salt (10 to 15%). This represents an osmotic pressure response

Answer 58

obligate halophilic bacteria