Abstract: Through comparing the physiological characteristics of soil bacteria isolated from two different media, a significant difference between two populations of bacteria is found. Bacillus sp. mainly grows on rich medium and hardly on poor one, but Pseudomonas sp. and stick like bacteria can grow on the both, which is related to the different adaptability ofbacteria to the environment.

Key words: Soil bacteria, Isolation, Identification, break trend analysis, extreme climatic events, temporal and spatial variations, climate change, Songnen Grassland