Cultural Methods

Question 1

Why culture microorganisms?

Answer 1

-essential for understanding their properties and functions in the environment
-access to the material needed for detailed studies of their biology

Question 2

What do culutre-independent methods rely on?

Answer 2

the knowledge from cultivated species for the design of DNA probes, validation of experimental protocols, and interpretation of results

Question 3

Who pioneered the techniques of cultivation-based

Answer 3

winogradsky and beijerick

Question 4

what is the disadvantage of culturing microorganisms

Answer 4

strongly underestimate the number of microbes in the environment and cannot quantify the true microbial diversity in nature

Question 5

what percentage of bacteria population is culturable

Answer 5

<1%

Question 6

What percentage does carbon constitute?

Answer 6

50% of dry weight

Question 7

What percantage does N constitute?

Answer 7

13%

Question 8

What are other macronutrients cells need in smaller amounts?

Answer 8

P, S, K, Mg

Question 9

What are the two types of media?

Answer 9

defined and complex

Question 10

What can culture media be in terms of growth

Answer 10

nonselective, selective, semi0selective and differential

Question 11

what is selective media

Answer 11

inhibit growth of organisms other than the one being sought

Question 12

what is differential media

Answer 12

contain a substance that certain bacteria change in a recognizable way

Question 13

What is the benefit for differential media

Answer 13

media for rapid screening and ID of microorganisms use certain dyes and organic compounds that fluoresce under UV or produce distinctive

Question 14

What is enrichment?

Answer 14

helps to grow a detectable population of cells from a very low initial level

Question 15

What are enrichment techniques used for ?

Answer 15

recover injured microorganisms

Question 16

What does selective enrichment do?

Answer 16

furthers the growth of the target while suppressing the competing microflora with temperature, antimicrobials, salts, acids, and metals

Question 17

What does nitrobacter do?

Answer 17

oxidize NO2- to NO3- by the enzyme nitrite oxidoreductase with electrons

Question 18

What is nitrobacter used for?

Answer 18

isolated using a multistep serial enrichment technique because

Question 19

what is the purpose of isolation?

Answer 19

obtain isolated colonies. so that pure cultures of the target organism will be available for the identification tests

Question 20

Why do preenrichment?

Answer 20

to allow the stressed target organism to resuscitate in either a non-selective or moderately selective medium

Question 21

how much growth occurs during preenrichment?

Answer 21

very little

Question 22

What are conventional microbiology procedures known by

Answer 22

-nature labor-intensive and time-consuming

Question 23

what are the three areas of major improvement that have been achieved

Answer 23

1) sample preparation
2) separation and concentration of target cells
3) end detection

Question 24

What is the countable range for plates?

Answer 24

25-250

Question 25

what is dry rehydration method

Answer 25

petrifilms are ready-made culture medium systems

two plastic films coated with standard method nutrients , a water-soluble gelling agent, and a tetrazolium indicator that helps to enumerate colonies

Question 26

what is spiral plater

Answer 26

special count grid, which relates the area of the plate to the sample volume

Question 27

What does MPN stand for

Answer 27

Most probable number count

Question 28

Which is the only agar media-based diagnostic kit system

Answer 28

enterotube II

Question 29

what is the most widely used dehydrated media minikit

Answer 29

API

Question 30

What is API 20E

Answer 30

has 20 small elongated wells with dehydrated media housed in a plastic panel

Question 31

What do microtiter plates contain?

Answer 31

dehydrated media with different C, N, P, S substrates

Question 32

What happens during incubation with microtiter plates

Answer 32

microorganisms oxidize substrates in the plates wells and simultaneously reduce colorless tetrazolium dye to a colored product

Question 33

what are novel methodological developments

Answer 33

-improved soil dispersion protocol
-using dilute media
-replacing agar with gellan gum as a solidifying agent
-very long incubation times
-careful inspection of plates for barely visible colonies
-dilution-to-extinct approach that helps to isolate and protect slow-growing organisms