Friendly microbes are yeasts, Lactobacillus, Rhizobium.
Yeasts are used commercially for making bread and alcoholic beverages. Rhizobium is a nitrogen-fixing bacteria present in nodules of leguminous plants which convert atmospheric nitrogen into nitrites and nitrates. Lactobacillus converts milk to curd.
Harmful microbes are malaria parasite, Bacillus anthraces, bread mould.
Malaria is caused by mosquitoes. The parasite present in the saliva of female Anopheles mosquitoes when it bites causes malaria. Bacillus anthraces is the causative pathogen of anthrax. Bread mould spoils the bread and when these spoiled bread is consumed it can cause food poisoning.