VBNC

Question 1

VBNC

Answer 1

Viable but nonculturable state
-Bacterial cells maintain viability and metabolic activity but cells do not grow and do not multiply on/in routine (medium that B usually grow on) bacteriological culture media

Question 2

VBNC prupose

Answer 2

Cells enter in response to environmental stresses, thus making for long term survival in environment
-It is a state where they are nonculturable until they exit the state

Question 3

VBNC genera

Answer 3

16 genera
include:
-Enterobacteriaceae
-Vibrionaceae

Question 4

Problem with estuarine bacterium

Answer 4

Includes Vibrio vulnificus
-USA: 52,000 illnesses and 100 deaths
-seafoods and tatoos (after you get into water body)
-Wound infections lead to 25-50% mortality rate

Question 5

VBNC triggers

Answer 5

Environmental stresses such as:
-Temp, salt conc, oxygen conc, level of light, selective media, growth limitng factors

Question 6

Graph of VBNC

Answer 6

Question 7

Resuscitation from VBNC

Answer 7

-several structura; changes
-Changes in synthesis, respiration state and nutrient transport

Question 8

Vibrio vulificus resuscitation

Answer 8

within 8 hours from stress there will be some culturable cells
within 12-24hr: same amount of cells will be found as before stress

Question 9

Legionella pneumophila VBNC

Answer 9

Entry = nutrient deprivation

Question 10

Growth curve for batch culture

Answer 10

Lag
exponential
stationary
death

Question 11

Exponential growth

Answer 11

B divide at constant intervals with max growth rate
Arithmetic scale is constantly increasing slope
log scale is straight line

Question 12

generation time/ doubling time

Answer 12

Pop will double in number specific length of time

Question 13

Future pop size formula

Answer 13

Question 14

n formula

Answer 14

Question 15

Growth rate constant formula

Answer 15

Question 16

Generation time formula

Answer 16

Question 17

Detection and enumeration of VBNC

Answer 17

1. Acridine orange direct counting
2. Fluorescent Ab (or DNA probes)
3. Direct viable count

Question 18

Acridine orange DC

Answer 18

Treat cells with acridine orange:
DNA will show up as green and RNA as orange
RNA indicates cell is metabolically activey

Question 19

Acridine weakness

Answer 19

CAnt differentiate between low and no RNA

Question 20

Fluorescent Ab

Answer 20

Use fluorescent antibodies or DNA probes
-Cannot differentiate between dead and viable cells

Question 21

DVC

Answer 21

Direct cell counts
-can be combined with fluorescent ab
-Nalidixic acid inhibits DNA synthesis (but allows cells to elongate without dividing which enables the determination of viability)
-Yeast extract is added
-Morphology is NB as viable will be rod-shaped

Question 22

AS yet uncultivated

Answer 22

Media and culture conditions not adequate or unsuitable
-often for B that have never been cultivated

Question 23

Test food and water

Answer 23

Food:
homogenise food
-dilution series
-do streak plates
-determine CFU/g
water:
-Filter water and then overlay filter over agar to determine CFU/ml

Question 24

Why growth only occurs after 7hr

Answer 24

B are used to very little nutrients and so pumps in too much after exposure
-Metabolic rates become too high, which causes superoxides to form
-Cell needs time to adapt to environment as changes only happen gradually in nature