OD620 of a Listeria culture

N10 navigator10 at hotmail.com
Sun Dec 28 13:19:35 EST 2003

""Hanhong Dan"" <danh at inspection.gc.ca> wrote in message
news:sfe706e6.071 at NCRXEM7...
Dear netters,

Merry Christmas!
I have a problem in growing Listeria monocytogenes in LB broth overnight to
reach a OD620 >0.5.  I have tried: 1) make fresh broth batch; 2) pull out
the -70 C glycerol stock and streak on LB plate to isolate single colony and
start over, 3) grow seed bacterial culture using this new single colony at
day time for 7 hours and subculture at 1:100 dilution into the new flask
overnight with agitation, but all failed. From my labmate, it is clear the
same strain performed pretty well in about one year ago in LB broth and
OD620 can go up to 1.5 after overnight growth. Do I need to pass through
mouse to revive it ? Any clue will be most appreciated.  Hanhong Dan

Hanhong Dan
(613) 228-6698 (4914) | danh at inspection.gc.ca   | Facsimile / Télécopieur :
(613) 228-6673
Research Technician, ADRI, Canadian Food Inspection Agency
Technicien de Recherche, IRV, Agence canadienne d'inspection des aliments
3851 Fallowfield Road  | 3851 chemin Fallowfield Ottawa ON K2H 8P9
Government of Canada | Gouvernement du Canada

Hi Hanhiong

Sounds to me like the isolate has degraded competance as evidenced by the
extension of lag phase.

You could try using a less selctive medium at all stages after all it is
already in defined pure culture right.

Probabley your easiest solution is to purchase a new type culture.

Best Des

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