First check the efficiency of your consortium in degrading or remediating the contaminated soil under laboratory conditions. Optimize the parameters such as pH, inoculum concentration, temperature etc. in bacterial growth media containing oil (either crude oil, diesel, or any other lubricating oil) and then go for soil experiment. 

Studying the lipase activity or lipid degradation is essential for cleaning  the contaminated soil. Also can go for PAH estimation (before and after treatment).

Dear  Awad,

You have to perform the all  relevant biochemical characterization such as enzymatic assay and degradation activity of the isolated strains in vitro. After this you will be able to judge the suitable strain for which have the potential for cleaning the oil contaminated soil. Consequently you have go for the compatibility test of the selected microbial strains for the consortia development. If all the above mentioned analysis and tests are good, then and then   you can go forward for the consortia.

Good Luck 

Dear Awad,

As our colagues adviced you to do the biochemical characterization. Nevertheless I strongly suggest that you first try the remediation capacity on soil aritficially contaminated of the consortium optimizing the inoculum concentration (try different concentrations, for PGPR the most common concentrations are 107-108 cfu/ml). You should think very well you controls if you want to know what bacterias of your consortium are really necessary for the decontamination process. Finally you should do the biochemical characterization to the selected consortium.

Best regards!

Lourdes

Dear . Awad

Concerning the best way to use a consortium of bacteria for cleaning oil contaminated soil: you may find useful information in the following articles:

Varjani S.J. and Upasani V. N. (2013) Comparative Studies on Bacterial Consortia for Hydrocarbon Degradation. International Journal of Innovative Research in Science, Engineering and Technology 2 (10), 5377-5383.

Mrozika, A. and Piotrowska-Seget Z (2010) Bioaugmentation as a strategy for cleaning up of soils contaminated with aromatic compounds. Microbiological Research, 165 (5), 363–375.

Both articles are attached

Best wishes Elsheikh

Laboratory experiments in liquid medium is the first step to know what contaminants your bacteria are able to degrade. However, I might suggest you to jump as soon as possible in artificially contaminated soil. A lot of bacteria showing dramatic capacity to degrade contaminants in liquid medium, exhibit poor results once in a soil.

Any decontamination process depends of biotic and abiotic conditions and you must  understand as much as you can about them for your precise case. 

Did you make a physical and chemical  characterization of your contaminated soil?

Are you  aware of the bioavailability of the different compounds? 

Which is the nutrient balance in your soil, in terms of Nitrogen and Phosphorus (a least these two)

The presence of inhibitors , as for instance heavy metals, can hinder the biodecontamination process , even if you have good lab results with your consortium.

Have also in mind that some times intermediate degradation products may be toxic and also prevent the biodegradation process. Follow the decontamination process with an ecotoxicity test is also important if you can do it.  

I don´t know what type of equipment do you have , but there are some simple soil reactors that can be used for these studies. 

 Good look , hope this information can be useful to you, 

look in page 101 of wtw catalogue http://www.wtw.de/fileadmin/upload/Kataloge/Labor/WTW_Lab-Catalog_2012_English_lowres.pdf

you should be aware that your consortia will have to compete with natural soil microcosm, which will be especially problematic for older contamination with adapted micros.