Absolutely. In the garden the Trichoderma family of fungi is considered to be a good because they kill the disease causing fungi. When you apply ordinary corn meal, the population of beneficial Trichoderma rapidly multiplies for about 10 days and the population of disease causing fungi rapidly diminishes.

If you want to ask whether adding corn meal will affect non-disease causing microbes, I would guess that there are some beneficial microbes that are negatively affected. With around 100,000 microbes in the soil food web, it is really hard to know what other effects there might be.