Abstract: Totally 44 bacterial strains were isolated from 9 soil samples collected from Guangdong, Hebei, Liaoning, Hunan and Jiangsu by diluted plate method. The protease-producing ability of the bacteria isolated was screened by transparent cycle plate assay. The results indicated that of these bacterial isolates, 16 exhibited clear transparent cycles. Meanwhile, strains G1-b, GD-2-2 and HX-B-1 revealed the strongest protease activity. The ratio of transparent circle diameter to colony diameter was higher than 3.5. Strain GD-2-2 had stronger protease activity than the other two, reaching 447.6 U/mL. Based on morphological observations and physiological and biochemical tests, strain GD-2-2 belonged to Bacillus. The 16S rDNA sequence analysis showed that the isolate was 100% similar with Bacillus licheniformis strain YB915 (GQ996726.1). Therefore, strain GD-2-2 belonged to Bacillus licheniformis.

Key words: bacteria, protease, identification