Q:

Grow oyster mushrooms in vacuum cleaner bags?

I'm giving oyster mushrooms a go, growing in coffee grinds in a plastic bag. Having an air filter in a bag, like the ones in purpose made mushroom bags, is a recommended technique.
What if I used a vacuum cleaner bag ? These allow air passage and also filter out small particles. Workable idea ?
I bought some that have a synthetic inner layer that I don't think the mushrooms would consume. What about maintaining a good moisture level by just spraying the absorbent bag ?
I'm a noob so let me know if these are bad ideas. Thanks.

A:

Normally you want to sterilize the substrate in a pressure cooker so those mushroom bags are designed to withstand pressure cooking for the 90 minutes required.  I suspect a vacuum cleaning bag is both more expensive than the 60c some charge for mushroom bags and not as robust.  
Coffee grinds are insufficient on their own to grow oyster mushrooms successfully. You need more carbon added to the mix.  
You need to sterilize coffee grounds as otherwise you'll just grow trichoderma.  You don't need to sterilize straw as trichoderma doesn't grow that well on straw and so pasteurization is sufficient. (The same applies to cardboard which can just be boiled.)  That leaves enough good bugs alive to combat any pathogens that might want to colonize the straw.  

