Isolation of chromosomal DNA
Chromosomal DNA was prepared from an 18 hrsculture at 30°C of BS11 in Trypticase Soy broth (TSB). Cells were harvested after centrifugation at 9,820 g for 3 min and
suspended in 500 l of 50 mM Tris-HCl, pH 8.0, 5mM (TE buffer). After freezing at -80°C and thawing cells at 100°C, each of 5 min for five times, suspension was re–centrifuged at 25,931 g for 10 min. The supernatant was added with 1xvolume of phenol chloroform for DNA extraction. The aqueous upper layer was transferred into fresh tube and
1/10x volume of 3M Na-acetate and absolute ethanol 2xvolume were added and kept at -20°C for 1 h. DNA was precipitated by centrifugation at 25,931 g for 10 min followed by washing with 70% ( v/v) ethanol, and centrifuged at 25,931 g for 10 min. DNA pellet were dried in heat box at 50°C, resuspended in 50 l TE buffer containing 1 l of RNase (10mg/ml), and incubated at 37°C for 1 h. DNA suspension was
kept at -20°C before use.
Isolation of chromosomal DNAChromosomal DNA was prepared from an 18 hrsculture at 30°C of BS11 in Trypticase Soy broth (TSB). Cells were harvested after centrifugation at 9,820 g for 3 min andsuspended in 500 l of 50 mM Tris-HCl, pH 8.0, 5mM (TE buffer). After freezing at -80°C and thawing cells at 100°C, each of 5 min for five times, suspension was re–centrifuged at 25,931 g for 10 min. The supernatant was added with 1xvolume of phenol chloroform for DNA extraction. The aqueous upper layer was transferred into fresh tube and1/10x volume of 3M Na-acetate and absolute ethanol 2xvolume were added and kept at -20°C for 1 h. DNA was precipitated by centrifugation at 25,931 g for 10 min followed by washing with 70% ( v/v) ethanol, and centrifuged at 25,931 g for 10 min. DNA pellet were dried in heat box at 50°C, resuspended in 50 l TE buffer containing 1 l of RNase (10mg/ml), and incubated at 37°C for 1 h. DNA suspension waskept at -20°C before use.
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