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zhangjingwjs

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Nowadays, I used the diluted spreading method to evaluate the density\population of the soil.
Firstly, 0.5 g of fresh soil was collected and put in a triangular flask with some glass beads.
Then shaking for 15 min, subsequently cooling down about 2 min, next smoking 10 ml into the 15 ml tubes, which was treated as 10-dilution solution.
then i ml from the 10-1 was taken and transferred to another 9 ml sterile water, which was as 10-2.
In a similar way, I got 10-3, 10-4, 10-5, 10-6, 10-7, 10-8, 10-9.
Finally, 1 ml of each diluted solution was spreading on the R2A plates, then put in the stove at 37 degree temperature for two days. three replicates of each treatment.
Now, my question is that why I found there was nothing on some plates but not all, for example one of the 10-6 and 10-5.
while on the 10-9 plates, there were much bacteria colonies, which was so strange.
Now i am wondering What happened during the operation <>
who knows ? please share your experiences here, thanks in advance!

[ Last edited by zhangjingwjs on 2016-6-20 at 00:39 ]

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