Using the
spectrophotometer to estimating the number of bacteria in a liquid medium (we
used LB broth) is to measure the turbidity or cloudiness of a culture and
translate this measurement into cell numbers. determine the optical density (O.D.) of the assigned
broth culture at 600 nm. for Stenotrophomonas maltophilia D457
Stenotrophomonas
maltophilia
(ATCC® BAA-84™)
Strain Designations D457
Isolation: Bronchial aspirate, Madrid, Spain
Biosafety Level 2
Strain Designations D457
Isolation: Bronchial aspirate, Madrid, Spain
Biosafety Level 2
The bacteria inoculated
on LB agar to obtained isolated colonies, a single colony inoculated into 9
tubes each one contains 3 ml of LB broth, the tubes were kept in 37 C၀ shaker incubator for 9 different
period of time as fallowing: 6:30, 7:30, 9, 10, 14, 16, 17:30, 19 hours
respectively; at the end of each period of time the OD600 of the broth culture
was measured also a 8 tenfold dilution of the broth were
made(1/10,1/100,1/1000……1/10^8) Transfer 0.1 ml of the final dilution to triplicate LB agar plates.
Turb
Result:
CFU calculated using the formula CFU= (average # of colonies x d.f)/volume of
culture
|
Time in hours
|
CFU/ml
|
OD600
|
|
6:30
|
4.0*10^7
|
0.088
|
|
7:30
|
1.8* 10^7
|
0.217
|
|
9
|
2*10^8
|
0.4721
|
|
10
|
2.2*10^6
|
0.6048
|
|
14
|
4.1*10^8
|
0.9485
|
|
16
|
7.0*10^8
|
1.0971
|
|
17:30
|
1.9*10^8
|
0.8223
|
|
19
|
5.0*10^8
|
1.2402
|
No comments:
Post a Comment