I think you can avail microplate-96, but three facts need to be taken into account : 1. Acidophiles grow in a sour environment that is aggressive and can injure material of plane-table, means to pick up a plane-table steady to acids; 2. Your bacteria of iron-oxidizing, means aerodes, take into account that a lid must provide access of oxygen of air. In principle really to find such plane-tables. 3. All dilutions and sowing you mast do in the laminar box. 

For experiment you need 4 microplate-96 (looking how many bacteria it was at the beginning of experiment and what dilutions will sow): first  microplate for dilutions, second, third, fourth for sowing.

I did not grow in the plane-tables of bacterium, but sure that at the observance of these terms for you all will turn out. 

 Thanks you Tkachuk.

Have got you some reference over it?

Thanks you in advance!

Unfortunately I do not have such references. Methodology of dilution of bacterial suspensions and sowing for determination MPN is the same as well as in test tubes. Charts are in textbooks on microbiology. 

You may perform some experiment this way, but the results will not be statistically valid and hence you will never get reproducible results.

Really the methods of MPN must be used with a carefulness, as there is considerable variation of results. Acceptability of results depends both on the number of the analysed tests and from a decision to use or cast aside the results of categories of less credible results. And certainly the tenfold delutions it is necessary to do in tubes (!!). Sorry.

Does can you will be able to estimate the approximate amount of viable microorganisms on Petri dishes? Pay attention, that the medium with agar intended for cultivation of acidophilus sterilize at the neutral value of рН and only after autoclaving acidify (otherwise a medium will remain liquid because an agar will lose the properties).

Good luck!

I really wouldn't recommend solid-media culturing based techniques for acidophiles. Many relevant species are well known to be very difficult to cultivate in solid media. That's why until late 90's Acidithiobacillus ferrooxidans (Thiobacillus ferrooxidans back then) was considered to be the main organism in bioleaching operations, and it was not true as it could be seen when molecular biology techniques started to be used. See for example Rawlings et al., 1999.

I know that this techniques can be expensive but at least keep it in mind.

If you just want viable cells try a dead/live staining, e.g. fluorescein diacetate, if you can access to it.

Article Reasons why 'Leptospirillum'-like species rather than Thioba...

Xavier, Thanks for your request. 

The molecular methods are expensives.

In 1999, Dra. Blanca Escobar (U. Chile) published a artcile about the MPN for acidophiles.

Furthermrore, Dr. Barrie Johnson also recommends this method considering some guidelines.

Thanks to all friends.