On this sub I see many questions seeking clarification of contamination versus bruising. Frequently I see photos during the stages of spawning to bulk and fruiting. My question is where is this contamination coming from? If the substrate has no nutrients, and the grains were fully colonized before adding them to the substrate, then it must mean one of the following is true:
—contamination entered during the inoculation and colonization stage and simply didn’t show up until a few weeks later
—the grains were not fully colonized before moving to the spawn to bulk stage, thus allowing bacteria to feed on the grain nutrients still existing from colonization
—random bacteria was preexisting somewhere in the setup prior to spawning to bulk and the cleaning step with alcohol wasn’t thorough enough.
What other potential avenues of contamination am I not thinking of?