Deactivation of bacteria for competition study - (May/16/2013 )

Hi all, I'm a new user in this forum and register specifically to ask this question;

I'm doing fungal fermentation. Every now and then I do have some contamination but it wasn't serious. I didn't use any antibiotics as my fungus is usually strong enough to overcome the contamination (I do practice sterile techniques)

I've been only analysing the one metabolite produce by the fungus (metabolite A). Only recently I was able to analyse another metabolite that was said to increase as metabolite A increases (metabolite B )

I was surprise to see how random the production would be compared to metabolite A. After some time, I suspect metabolite B was being produced as a response to the contamination, hence that is why the production is so random even within the same replicates (while metabolite A was so stable in production)

I already cultured the contaminating bacteria. I'm thinking of introduce them into my fungus culture in 2 different conditions - live and deactivated (like vaccine). Does anyone in this forum has experience in deactivating bacteria for this kind of study? I afraid heat would change the conformation and chemical would be too poisonous to my fungal culture.

Could you try something like LPS (lipo-polysaccharide, commercially available) that is produced by the bacteria?

Freeze-thaw cycles? That's just breaking down cells and avoids chemicals or heat-induced changes. But sterility may need to be evaluated, I don't know how many cells may survive, if any.