Of the five major groups of microorganisms: bacteria, actinomycetes, fungi, algae and protozoa, all but the protozoa contain members that can have a beneficial effect on plant growth.

• 5种主要的微生物有：细菌、放线菌、真菌、藻类和原生动物。除原生动物外，其它种群里都含有对作物生长有益的种类。