the pretreatment does change the crystalinity index of the cellulose. There are lots of papers out there discussing about this. What does the Trichoderma do during your fermentation?

Some time ago, I had the same question, but this papers helps to understand best the Cellulase induction by different substrates. I hope this will help you.

First, we need to understand that the lignocelluloses are composed of both cellulose and hemicelluloses. Depending on which type of pretreatment, hemicelluloses may be removed (dilute acid for example), so you are left only with the cellulosic part. Some fungal isolates have been proven to be capable of co-fermentation of hexose and pentose sugars which are present in the untreated rice husk. So the disparity may be as result of the removal of the hemicellulose part of the treated substrate.

In addition to above-mentioned there are other explanations.

1. Pre-treated substrate is rapidly hydrolysed and accumulated sugars cause a catabolite repression of cellulase synthesis.

2. It contains some inhibitors of fungus growth and enzyme synthesis.

3. Compare the pH-profiles in two media. Maybe in pre-treated straw fermentation it is lower delaying the fungus growth and enzyme secretion and inactivating also synthesized enzyme.

4. Try to test and compare different concentrations of both materials.

I'm actually work on cellulase production by fungus. I'm also work with lignocellolosic biomass.

In the beginigns of the project we were in the same problem : Low production of the enzymes, one of the problems was the low growth of the fungal biomass... we solve this problem adding an "Alternative Carbon source" to keep the Growt but in a small portion, when the fungus was growth and the alternative source is finished, the fungus was "forced" to produce enzymes to degradate the Lignocellulosic biomass...

What Kind of Fermentation you use to produce the enzymes? Solid State? Submerged? For the fungus (Deuteromycota, like Aspergillus, Trichoderma) its better to use Solid state because the difussed oxygen its better.

So, in the other hand What methods are you using to measure the enzyme production? Direct (Specific substrate like b-Glucopyranosides? undirect (Reducing Sugars by Miller method)? check this because is very important and most important is... What type of Cellulase you want to produce? Endoglucanases, Exoglucanases or B- glucosidases?

If you need something send a Mailbox.

Best Regads and Good Luck.

It is simple. Whenever a complex lignocellulosic material is used as a carbon source in the medium for cellulase production the cellulase production is higher as compared to a pretreated biomass or a purer cellulosic material e.g. avicel. The reason is that when using a non-pretreated biomass, the organism has to  secrete more enzymes to break that cellulosic material into simpler monomeric sugars for its own growth. But when the pretreated material is used, then a lower expression and/or secretion of cellulase might fulfill its growth requirements. So the cellulase production is dependent upon the lignocellulosic material that you are using.

thanks to all your comments, it was helpful