In theory you can concentrate cells by filtration or centrifugation, but probably no more than 100 fold. in your case you are asking to concentrate by 10,000 fold. So you really would need to grow a denser cultures of cells.
Hi Momina,
Your initial bacterial solution (10^5 UFC/ml) is more diluted than 10^9 UFC/ ml. So you have to streak your strain on an agar plate and make a new bacterial solution (Mc Farland or OD=1 at 540nm). Good Luck.
In theory you can concentrate cells by filtration or centrifugation, but probably no more than 100 fold. in your case you are asking to concentrate by 10,000 fold. So you really would need to grow a denser cultures of cells.
You can centrifuge your current broth and resuspend the pallet in a fresh broth. Grow for another 4-6 hours. Which bacteria are you working on? Different bacteria may need more supplement to grow, eg. lysed blood for Streptococcus pneumoniae.
You can use a McFarland standard to check the approximate density in a broth or saline solution of cells.
This is done routinely for susceptibility testing of bacteria where the goal is to start with a suspension of cells measuring the same as a 0.5 McFarland standard. This measurement produces a suspension with approximately 1.5 x 108 cfu/mL. To get up to 1 x 109cfu/ml you would use a McFarland standard between 3 and 4. Where a McFarland suspension of 3 = ~ 9X108cfu/mL and a McFarland suspension of 4 = ~ 1.2X109cfu/mL.
The density of your suspension can be compared to the density of a 4 McFarland standard using a densitometer or a nephelopmeter. These standards can be purchase or made in house.
You can pellet the cells and resuspend them in a much lesser volume of the medium. You can then check the OD w.r.t. the McFarland standard as mentioned by Maria Traczewski.
Dear Momina
I also recommended you use the method that Baddredine suggested. Use a bacteria culture in the logarithmic phase not incubated longer than 18 hours depending on the genus, so that you have active growing cells when making the
Mcfarland solution.
Francien
Dear Rauf
The zero point bacterial solution (10^5 UFC/ml) is more diluted than 10^9 UFC/ ml. Thus, you have to streak your strain on an agar plate Like brain heart infusion agar with blood and make a new bacterial solution (Mc Farland or OD=1 at 540nm).
Hope i helped you
You can reconcentrate the cells by pelleting and resuspend them in half of the orignial volume of the medium. Then, you can check the OD at 600 nm or the McFarland standard.
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