I think people get too hung up on substrate constituents. It makes sense that folks who rightfully concern themselves with the nutritional aspects of soil or hydroponic liquids.
It's a plant and plants like or need all kinds of micronutrients, ballances, pH, oxygen permeability and.. All that.
Most folks here seem to really know what they are talking about when it comes to cannibis growing. I do not.
But mushrooms are not plants. Mushrooms are far more like animals than plants. They give off carbon dioxide.
The things they eat start off being verystronger, feed them simple chemicals like you do plants and you will fail.
Mushrooms adapt to all sorts of foods. They actually thrive on variety,it keeps th m on their toes.
So....if you have the moisture content right, if your pH is even close, if there is even something at least close to what the mushroom can grow on then it is enough.
I've grown mushrooms on dog food, cheese, wood, corn, straw, brown sugar, coffee grounds, paper, coir, cardboard, manure, oil saturated grains, water beads with sugar water.... Point is, I have found that if the specific needs are met, variations in thecsubstrate are pretty much superfluous. You can't make them much stronger or much more prolific with some magic substrate or supplement.
But I could be wrong.