A bacterium producing the alkaline pretense was isolated from Chungkookjoug, and was identified as Bacillus subtilis JK-1 based on morphological, physiological and biochemical characteristics, as well as phylogenetic analysis using 16S rRNA gene sequence. The optimum pH and temperature of the pretense activity were pH 9.0 and $55^{circ}C$, respectively. This enzyme was stable at the temperatures $40{sim}80^{circ}C$. The maximum alkaline pretense production was obtained when 1.0% (w/v) xylose, 1.0% (w/v) yeast extract and 0.3% (w/v) $CuSO_4$ were used as carbon source, nitrogen source and mineral source. Under the optimal condition, growth of the isolate was reached at stationary phase after 12 hr followed by incubation, the alkaline pretense production reached a maximum level with $16{sim}20$ hr cultivation.