title: The optimization of fermentation conditions and enzyme properties of Stenotrophomonas maltophilia for protease production.
abstract: Intestinal bacteria play a significant physiological role in silkworms. Proteases secreted by intestinal microbes can promote the digestion of the nutrient by Bombyx mori and the absorption of mulberry leaves. Intestinal bacteria from Jingsong × Haoyue in the fourth larvae were isolated and purified to obtain high activity protease-producing bacteria. The morphology of the identified bacterial colony was examined by microscopy combined with the 16S rDNA method. The results showed that this bacterium was Gram negative and that it belonged to Stenotrophomonas maltophilia, which produces the proteases. To improve the utilization rate of these proteases, we studied the proper culture conditions for producing proteases, and we further studied the properties of the proteases that were produced. The results showed that the optimal enzyme-producing conditions were as follows: pH of 7.0, culture temperature of 35 °C, incubation time of 36 H, and outfit fluid amount of 60 mL per 100 mL. Meanwhile, the properties of the preliminary enzyme purification indicated that the best pH of the enzymes was 9.0 and the optimal reaction temperature was 50 °C. The enzymes are alkaline proteases that show satisfactory stability at 30 °C and pH 9.0. Consequently, it is suitable for the proteases secreted by S. maltophilia to play a bioactive role in the silkworm gut.
authors: Department of Life Science, Anhui Agriculture University, Hefei, Anhui, People's Republic of China.
authors: Zaigui
authors: Z
authors: Wang
authors: Department of Life Science, Anhui Agriculture University, Hefei, Anhui, People's Republic of China.
authors: Linghong
authors: L
authors: Sun
authors: Department of Life Science, Anhui Agriculture University, Hefei, Anhui, People's Republic of China.
authors: Jia
authors: J
authors: Cheng
authors: Department of Life Science, Anhui Agriculture University, Hefei, Anhui, People's Republic of China.
authors: Chaoliang
authors: C
authors: Liu
authors: Institute of Animal Science, Chinese Academy of Agricultural Sciences, State Key Laboratory of Animal Nutrition of China, Beijing, People's Republic of China.
authors: Xiangfang
authors: X
authors: Tang
authors: Institute of Animal Science, Chinese Academy of Agricultural Sciences, State Key Laboratory of Animal Nutrition of China, Beijing, People's Republic of China.
authors: Hongfu
authors: H
authors: Zhang
authors: Department of Life Science, Anhui Agriculture University, Hefei, Anhui, People's Republic of China.
authors: Ying
authors: Y
authors: Liu
mesh_terms: D000818:Animals; D012831:Bombyx / Q000378:metabolism / Q000382:microbiology; D005285:Fermentation; D010447:Peptide Hydrolases / Q000096:biosynthesis* / Q000378:metabolism; D020615:Stenotrophomonas maltophilia / Q000201:enzymology* / Q000378:metabolism
chemical_list: D010447:Peptide Hydrolases
keywords: culture conditions; enzyme properties; intestinal bacteria; protease; silkworm