Abstract: Gene Regulation Induction of B-Galactosidase in Escherichia Coli, Comparative Analysis Between Two Strains
Mentor: Dr. Haideh N. Lightfoot, Biology
Escherichia coli (E.coli) is a lactose fermenting, gram-negative, rod shaped bacterium, and a member of the normal intestinal flora in most animals. This study examined two strains of E. coli using gene expression for B-galactosidase enzyme, which digest lactose sugar forming galactose and glucose. The lac operon is activated in the presence of specific inducer, such as lactose or IPTG. The induction of B-galactosidase activity was measured in two different well-known laboratory strains of E. coli. Each strain was grown overnight and the bacteria were washed, and suspended in minimal Davis medium with glycerol. Lactose alone, lactose and glucose, IPTG, and glucose alone in day cultures induced the lac operon. After incubation, of at least one hour, the level of B-galactosidase activity was measured using ONPG (an artificial substrate for the enzyme), which produces a yellow nitrophenol color. One strain produced the nitrophenol coloring more rapidly than the other strain, indicating tht the degree of induction of B-galactosidase was different in different stains of E. coli. This is useful information for developing experiments for the detection of this or other enzymes for undergraduate laboratory teaching. Level of gene activity may be different from one strain to another affecting the time and the conditions for testing, which need to be considered in the design of these experiments.
7th Annual Research & CW Symposium, EWU, May, 19, 2004
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8th Annual Research & CW Symposium, EWU, May 18, 2005
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