Relationship with human beings There is a close relationship between microorganisms and human beings Beneficial activities most microbes are of benefit to human beings, some are necessary. eg. nitrogen, carbon cycles, etc Harmful activities: Only a small portion of microbes cause diseases and are poisonous to human, and these pathogenic microbes are really that concern us in the study of medicine•There is a close relationship between microorganisms and human beings. • Beneficial activities: Most microbes are of benefit to human beings, some are necessary. eg. nitrogen, carbon cycles, etc. • Harmful activities: Only a small portion of microbes cause diseases and are poisonous to human, and these pathogenic microbes are really that concern us in the study of medicine. Relationship with human beings