Bacillus cereus and its Resistance to the Antimicrobial, Nisin
Location
CSU 202
Start Date
21-4-2008 10:00 AM
End Date
21-4-2008 12:00 PM
Student's Major
Biological Sciences
Student's College
Science, Engineering and Technology
Mentor's Name
Dorothy Wrigley
Mentor's Department
Biological Sciences
Mentor's College
Science, Engineering and Technology
Description
Bacillus cereus is a gram positive microorganism which causes mild food borne illnesses. Nisin, naturally produced during some food fermentations, is an effective antibiotic against gram positive pathogens. Elevated use of nisin may contribute toward increased bacterial resistance to such treatment. This study examines changes in microbial cell surface charges, as an effect of acquired resistance. B. cereus was cultured with nisin and without nisin and compared for changes in cell surface charges by their binding of the cationic dye, Congo Red. The two cultures were suspended in Congo Red and briefly incubated. Then the bacteria were removed by centrifugation, and the dye remaining in solution was measured. The difference between the original dye absorbance and the dye mixed with bacteria was used to quantify a percentage of absorbed dye. Optimal conditions for pH and dye concentrations were determined. Under the best conditions, nisin-conditioned B. cereus bound 70.55% of the Congo Red, while the unconditioned B. cereus culture bound 51.9%. Clearly, the unconditioned B.cereus culture reduced Congo Red binding activity. Thus phenotypic expression of acquired nisin resistance strongly correlates with a change in the cell surface charge.
Bacillus cereus and its Resistance to the Antimicrobial, Nisin
CSU 202
Bacillus cereus is a gram positive microorganism which causes mild food borne illnesses. Nisin, naturally produced during some food fermentations, is an effective antibiotic against gram positive pathogens. Elevated use of nisin may contribute toward increased bacterial resistance to such treatment. This study examines changes in microbial cell surface charges, as an effect of acquired resistance. B. cereus was cultured with nisin and without nisin and compared for changes in cell surface charges by their binding of the cationic dye, Congo Red. The two cultures were suspended in Congo Red and briefly incubated. Then the bacteria were removed by centrifugation, and the dye remaining in solution was measured. The difference between the original dye absorbance and the dye mixed with bacteria was used to quantify a percentage of absorbed dye. Optimal conditions for pH and dye concentrations were determined. Under the best conditions, nisin-conditioned B. cereus bound 70.55% of the Congo Red, while the unconditioned B. cereus culture bound 51.9%. Clearly, the unconditioned B.cereus culture reduced Congo Red binding activity. Thus phenotypic expression of acquired nisin resistance strongly correlates with a change in the cell surface charge.
Recommended Citation
Felske, Kristy. "Bacillus cereus and its Resistance to the Antimicrobial, Nisin." Undergraduate Research Symposium, Mankato, MN, April 21, 2008.
https://cornerstone.lib.mnsu.edu/urs/2008/oral-session-04/6
