EXERCISE 10

Question 1

Most important pathogens that are water-borne

Answer 1

Vibrio cholerae & Salmonella enterica

Question 2

COLIFORMS:

• oxygen level
• type of bacteria
• spore forming?
• shape

Answer 2

aerobic to facultative anaerobe
gram - bacteria
non-spore forming
rod-shaped

Question 3

What kind of bacteria are coliforms

Answer 3

enteric (exist in intenstines of animals)

Question 4

the KEY fecal coliform of interest

Answer 4

Escherichia coli

Question 5

What is the test used for coliform?

Answer 5

MPN technique (most probable number technique)

Question 6

Significance of MPN

Answer 6

estimating population of microorganisms in samples with very low counts

Question 7

What are the 3 steps in MPN technique

Answer 7

1. Presumptive MPN
2. Confirmatory MPN
3. Completed Test

Question 8

What is the media used in PRESUMPTIVE MPN

Answer 8

LAURYL SULFATE TRYPTOSE BROTH with inverted Durham Tubes

Question 9

What are the indications for positive tubes in presumptive mpn?

Answer 9

turbidity and gas production in DURHAM TUBE

Question 10

what does turbidity denote in presumptive mpn?

Answer 10

there are microorganisms that can FERMENT LACTOSE but may not be coliforms

Question 11

What medium is used in confirmatory mpn?

Answer 11

Brilliant Green Lactose Bile Broth

Question 12

What kind of tubes are present in BGLBB?

Answer 12

Durham tubes too

Question 13

How much from each positive tube of presumptive MPN will be transferred to BGLBB?

Answer 13

only a loppful

Question 14

What are the indications for positive tubes in confirmatory mpn?

Answer 14

turbidity and acid production thru bubbles w/ or w/o yellowing

Question 15

what does turbidity denote in confirmatory mpn?

Answer 15

microorganisms are indeed coliforms

Question 16

purpose of completed test

Answer 16

to know what type of coliform

Question 17

How much from each positive tube of confirmatory MPN will be transferred to completed test?

Answer 17

loopful and perform streaking

Question 18

What medium is used in confirmed test?

Answer 18

Eosin Methylene Blue agar

Question 19

EMBA color results of the ff:

• coliforms
• e.coli
• other lactose fermenters
• non-coliforms

Answer 19

• purple/blue-black
• greenish metallic
• pink
• colorlesswa

Question 20

3 indicators of water quality

Answer 20

o fecal streptococci (Streptococcus faecalis)
o Clostridium perfringens
o Coliforms