What kind of media are you preparing?? specify this..otherwise, as I work on the production of biosurfactants, glycerol is used as a carbon source and it enhances the production of biosurfactants..this means it doesn't harm the microbes in this case..what sort of experiment are you performing ??

Thanksfull Garima Bhardwaj, for your response, for my experience, i just want to enhance growth of bacteria by adding diverse carbon source, and i read some where that glycerol can be use as carbon source, and in otherwise, i also read that glycerol can be use only for microbial conservation

When you use glycerol as a sole carbon source, bacteria grow much slower, but  stay alive on agar medium at room temperature for months.

ok Thanks @Alex Ignatov, for this answer, glycerol is not the only carbon source i use; i also use others substrates

Dear Vanessa,

If you are trying to enhance the growth of bacteria using glycerol as carbon source in addition with other carbon sources..you are doing right..pursue with this, you will get good results..

Cheers..

Dear Garima

Thank you for your response :) :)

Cheers

Hi

slow growth of your bacteria is not due to inhibition of glycerol, I though, it is due to microbes starting different pathway to use carbon from glycerol

Regards

Francesca, 

As carbon source, glycerol will promote growth of glycerol-utilizing microorganisms, and others will benefit from accumulation of secondary metabolites. The effect will depend on amount of glycerol added, type of soil and time of the year (temperature+water content). In regions with cold seasons it can help to maintain higher microbial population through winter time, but, in warm area it may promote survival of some plant pathogenic bacteria - they usually like glycerol.

I am not sure in effect on many pathogenic species (usually low temperature and low humidity favor survival of bacteria in soil), but glycerol must protect Ralstonia solanacearum (it is killed by temperature fluctuations around OoC). 

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4356456/

Some more information can be found in

http://www.annualreviews.org/doi/abs/10.1146/annurev.py.12.090174.001215?journalCode=phyto

https://www.apsnet.org/publications/plantdisease/backissues/Documents/1981Articles/PlantDisease65n08_633.pdf