Hi,

Your confusion about what, that's not clear, although, I used to mix different metal and metalloid salts (As, Cd, Hg, Pb, and Cr) into the media before autoclaving. Please be careful while calculating the total metal(loid)s concentration apart from their salts and add it to the un-sterilized media. Make a plate and go for the spread plate to get tolerant microbes. Also, remember to use a gradient of metal concentration to know the range of optimal tolerance and maximum tolerance of your microbes from the plates.

Best,

I interesting question because it's the free ion activities in the diffusion zone, not the concentrations, that govern uptake.

Dear Anjali Patil,

First, if you want to study the metal tolerance or Minimal inhibitory concentration (MIC) of bacterial isolates, my suggestion is to go with minimal media. Because in nutrient-rich media metals will get complexed and precipitated with the complex nutrients, giving false high tolerance and MIC results. Diluted TSA will also serve this purpose.

Second, prepare a stock solution of metal from metal salts and filter sterilize. Add this filter-sterilized metal solution to the autoclaved media as per your required concentration (use dilution formula). Check the literature for a range of concentrations to be used. Pour the plates and proceed with the spread plate or the streak plate method. This will give you tolerant varieties.

For bioremediation, from the stock solution add the metal to the cell suspension (fixed biomass) in minimal media broth. Grow them under optimal conditions. Take an aliquot of the sample at different time intervals, separate the cells and check the metal concentration in the supernatant.

Best wishes.

Hi Anjali Patil

In my dissertation i used a standard solution of heavy metals (Cu, Pb and Zn), with a concentration 8000 mg/l or ppm. Then i mixed with to liquid culture medium. If you want to now more about this, contact me I will sent to you my dissertation.