1st Student's Major
Biological Sciences
1st Student's College
Science, Engineering and Technology
Students' Professional Biography
Peter Weber grew up in LeCenter, MN and graduated from LeCenter Highschool in May of 1999. He started attending Minnesota State University, Mankato in the fall of 1999. He is currently majoring in Microbiology with a minor in Chemistry.
Mentor's Name
Dorothy Wrigley
Mentor's Email Address
dorothy.wrigley@mnsu.edu
Mentor's Department
Biological Sciences
Mentor's College
Science, Engineering and Technology
Abstract
Nisin is a peptide that is made by the bacterium Lactococcus lactis. Nisin is a small molecule that kills gram positive bacteria by binding to their membrane and by disrupting the proton motive force. When food is processed it is heated to kill bacteria, but some bacteria still survive. Adding nisin to the food provides a second barrier for the growth of the bacteria. Purified nisin has become quite expensive in the current marketplace. Therefore this study is directed at producing nisin and purifying it. L. lactis was grown in five different media (BHI, BHI + 1% glucose, BHI + 1% sucrose, BHI + 3% yeast extract, and skim milk medium). Samples of nisin from these media were filter-sterilized and tested for their ability to inhibit the growth of Lactobacillus viridescens, which is susceptible to nisin. It was found that nisin from the media BHI + 3% yeast extract after 8 hours of growth has a similar concentration as the standard, which was 1000 μg/ml. The nisin was then purified. An extraction process using ammonium sulfate was used to precipitate nisin out of the media. It was found that a 50% ammonium sulfate concentration precipitated out all of the nisin. The nisin was dialyzed against distilled water to remove the salts. The Minimal Inhibitory Concentration (MIC) of the extracted nisin, using Bacillus cereu and endospores was equivalent to a commercial nisin preparation at 1000μg/ml.
Recommended Citation
Weber, Peter
(2004)
"Nisin Resistance of Bacillus Cerus: Preparation of Nisin,"
Journal of Undergraduate Research at Minnesota State University, Mankato: Vol. 4, Article 16.
DOI: https://doi.org/10.56816/2378-6949.1168
Available at:
https://cornerstone.lib.mnsu.edu/jur/vol4/iss1/16
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