ArticleAuthors: Dao Thi Luong; Vi Dai Lam; Tran Thi Le Quyen; Ha Thi Hang; Pham Duc Ngoc; Duong Van Hop (2011-09-09)
A bacterial strain YS24 produced high level of extracellular protease was isolated from soil sample collected at Yen Son - Tuyen Quang. Based on the colony observation, cell morphology and the analysis of 16S rDNA nucleotide sequence, the strain YS24 was identified as Bacillus subtilis. The highest levels of extracellular protease production and bacterial growth were obtained by using medium V9 (g/l): Glucose-5; peptone-7.5; MgSO4.7H20-5; K2HPO4-5; FeSO4.7H20-0.1. Enzyme production corresponded with bacterial growth and reached a maximal level of 1,390 U/ml when the bacterium was cultured on the orbital shaker under following condition: at speed of 200 rpm, inoculum size of 7% , tempe... 
