I think that orange juice has essential materials for E. coli to survive.

What objective do you follow?

Plenty of nutrients and since E. coli can adapt to acidic conditions (it can pass through the stomach after all) then this is no real surprise. Unpasteurised juices can be a source of E .coli (EHEC) outbreaks in humans if contaminated

Apart from nutrient density and PH, the temperature at which the juice is maintained is also an important determinant of E. coli survival therein.

Thanks all 

Besides pH I recomend to verify the presence of some preservative ingredient, both itens deverse special attention.

Azimun,

I dont know the pH limits for that microorganism, and the kind of orange juice you are testing (comercial or home made), if it is comercial you may take into account the preservatives, also those juices have recived a thermal treatment so the intrinsic microflora is at low levels, so if the microorganism is acidophilic will growth perfect if you incubate it in its optimum temperature. If the organism is sensitive to acidic pH so would happen that the majoirty of the population die but some cells get resistant to that condition and survive... If it's home made and the intrinsic microfolora is in high levels the growth of yeats and moulds will rise the pH ledding to an a optimum pH for your microorganism permiting it to growth. 

The best thing you can do is to do an a growth curve in laboratory media with the same pH of your juice and measure the behaviour of the microorganism in an optimum temperature (control) and in your conservation temperature. This will give you so much information for your sampling time, lag phase, groeth rate, etc...

kind regards,

Juan

Orange juice has essential materials for E. coli to survive. Beside unpasteurised juices can be a source of E .coli (EHEC) outbreaks in humans if contaminated

Thanks a lot all of you for giving me valuable idea.

Is orange juice acidic? It could inhibit E. coli growth. Also, there could be preserves added, they could inhibit E. coli growth as well.

Thanks.

Dear Azimun,

E.coli can grow in fruit juices very well as it can adapt to varying pH.It can survive the gastric pH and the urinary pH and of course is well suited to the intestinal pH where it is a normal resident flora. Hence, pH alteration may not harm it as much as temperature and pressure would. Also,as there are many preservatives in commercial juices, you should use only naturally obtained orange juice.I suggest that you keep one set of uninoculated orange juice tubes/bottles as control,and inoculate your test organism into one set of bacteriological grade peptone water and one set of orange juice tubes/ bottles. Wish you all the best in your work.

@ Jharna. Could you please clarify it that why I need to use  one set in uninocualated orange juice and one set in peptone water since I just want to see the survivability of E.coli 0104 in juice(low pH-4) at refrigeration temperature? Although I have some idea, but I want to know your opinion. Please let me know.

Dear Azimun,

There are certain principles of Microbiology that we need to follow to understand the behaviour of microbes. The basis behind the idea of keeping uninoculated media as controls is to compare the change in your medium after incubation under the expected conditions,if your native medium (uninoculated medium) changes (either pH,appearance or colour etc.) after storage then how will you know what is happening in the tube where E.coli is inoculated? More so if you want to compare the survival ability of this organism then what is your control against which you are working/assessing?-here peptone water inoculated with the organism will act as your control. Please remember that without proper controls you may not be able to validate your findings.

Also I would like to know how you are sterilizing the juice or making sure that there is no extraneous contamination with any other organism before inoculating your test organism?

@ Jharna, Thank you very much for valuable suggestions and some basic questions regarding my experiment.  I am really seeking for these information to conduct my research under comparatively standard condition.I would like to inform you that 1. I used Orange juice bought from supermarket and before inoculation I checked any contamination by spreading of juice on LB plate and found no contamination. 2.  Before inoculation, I checked pH of the Juice and continued to check it every sampling time. 3. Before conducting this study ( Survival ability of E.coli 0104 and as a control O157 and C600 in orange juice, pH 4.0-5.0), I already checked one time survival ability of those three strains of E.coli in citric acid hydrogen phosphate buffer ( pH 5.0). Still do you think I need to inoculate of those 3 strains in the same time in orange juice and peptone water and  as I checked pH of orange juice before and after inoculation of bacteria, still I need to keep uninoculated  orange juice along with them. Please give me your opinion and suggestion which are really necessary for my experiment.

Sorry for any inconvenience.

Best regards

Azimun

Dear Azimun,

It is good that you have checked with proper controls which I was not aware of as you had not mentioned earlier and hence, I don't think that you will need the peptone water but you should still keep uninoculated orange juice as a control and check it at the beginning and at the end of the experiment. 

Best regards

@Jahrna, Thank you very much for your valuable suggestion regarding my experiment.