I think the lignocellulosic waste is the best waste for the production of cellulase enzymes ,

we used bagasse and rice straw in the production of enzymes.

Wide range of lignocellulosic residues are available for the production of cellulase.

We used corn cob for xylanase production, but  our yeast also produces cellulase in this substrate

You may combine any pretreated straw with wheat bran. if you use some fruit peels it is possible that the fungus may divert energy to pectinases production decreasing cellulase levels.

You can choose any lignocellulosic pretreated waste as your substrate as these are very cheap substrates available...for eg rice bran, wheat bran

You may used carboxymethylcellulose (CMC)  as a substrate because most of the reports showed it induced the production of cellulases by activating cellulose regulatory protein called the cellulase activator molecule (CAM)

You may use CMC as suggested by Dr Ahmad but if you add a detergent like Tween 20/80 in the broth, it will increase cellulase production.

Well, in our hands CMC is a really poor source for cellulase production; I would not recommended it. Pretreated lignocellulose residues alone or in combination with wheat bran are good choices. You may also add Twee 80 for better results.

Thanks everyone for your insights. We have tested apple peels, banana peels, corn cob, sugarcane-bagasse, grass for fungal fermentations. Moving towards yeast fermentation, particularly under SSF seems a bit tricky. But I got a number of useful suggestions through this post. In our case, CMC proved to be an inducer for endoglucanase along with co-induction of xylanase in few species. Instead of using CMC as a sole substrate we supplement the crude substrate with it to study the induction if there is any,

Lignocellulosic material in most fruit peels is commonly less than other type and part of plant eg. rice straw, bagasse etc. CMC is the best choice, but you also can try commercial cellulose. Addition of surfactant like Tween-80/20 might be useful in promoting the release of cellulase.

Banana peel is a good cellulase inducing substrate as I also worked on that but in case of bacterial cellulase. For yeast you can choose 'sugarcane bagasse' as it is a good inducer of cellulase and definitely you will get the most. All d best.

CMC is a noble substrate for the purpose. You may add some nitrogen alongwith like wheat bran or may be soyabean meal for the purpose.