Introductory Microbiology

Negative / harmful / deleterious interactions

Detrimental effects of one species on its neighbours are quite common in soil, and they are dictated by the decreases in abundance or metabolic activities of the susceptible organisms. This include;

a) Competition

b) Amensalism

c) Parasitism and predation

a) Competition

The rivalry for limiting nutrients or other common needs. In such situations the best adapted microbial species will predominate or infact, eliminate other species which are dependent upon the same limited nutrient substances. Eg: Competition between strains of Rhizobium derived from soil and those applied with legume seeds at the time of sowing.

The better competator enters the root hairs more frequently and it is responsible for a high % of nodules.

b) Amensalism

It is a negative interaction, in which the release of products by one species is toxic to its neighbours. Antagonism is a type of amensalism.