E.coli suddenly death?? - (Sep/30/2010 )

Hi all..

I grew E.coli in certain wastewater that enriched with yeast extract. I measure the growth rate by OD600. The bacteria seems to grow 'quite' good for 4 H. But, after that (6H, 12 H....till 24 H) the growth phase was suddenly decline. I am confused why the stationary phase occur briefly? The growth curve looks abnormal.

Is there anyone who know the reason why E.coli could suddenly death?
is it possible the bacteria doesn't have stationary phase?

Hola,there are some possibilities about it, but using waste water could be a toxicity problem. I have understand that you have a known strain of E.Coli ( Genotype?)that you seed in a yeast extract enriched waste water. How much yeast extract? What OD we are talking? 0.5 or less?. Why don´t add to the medium a bit of glucose as 0.1g/l and see if the OD drop fall at the same time or later,or more yeast extract in these case you could know if the cause is the medium (use any component up) or the water. What about pH? Try the same experiment with pure water. I suposse that you have any toxic contaminant. I hope that with some of this variants of the cultures you can get any of the explanations that you search. Good luck

You could be seeing lysis due to phage. The sudden decline could be due to a lytic burst, either from phage in the waste water infecting your E. coli -- if the waste water is unfiltered, or filtered inadequately -- or your E. coli may harbor a lysogenic phage that is being triggered to become lytic by some component in the waste water media.

The time of death for your E.coli does seem to suggest phage contamination, but that's a good point about making them a little bit happier by adding glucose!

The maximum OD600 is (only) 0.3 (4 Hours incubation).

adding some Glucose? Ummm...but I use transforman E.coli BL21 (DE3) pLysS harbouring pET. Is it OK? I mean, is it ok if we add glucose to a system which is operate Lac operon?
Well, it could be tried.

But, how about the sudden death?? I guess there is any toxin in the waste water. maybe something like heavy metal...(I dont know). still on investigation.

Puteri Q on Mon Oct 4 05:41:15 2010 said:

Hola, you will have your reasons for don´t use any conventional media. The strain that you use isn´t lacIq so constitutive expression you can have and sometimes induced cultures fall after four hours of induction. Glucose repress the scape because growing on it the cAMP levels are low, and if you induce with IPTG glucose presence doesn´t matter. Probably if you use any of the BL21 LacIq you wouldn have the problems. Good luck

Oook I see..
Thank you...