Characterization of Bacillus bacterial strains is an important step in identifying and removing biofilms contaminating processing equipment. These biofilms lead to large amounts of spores in the final product. Strains that produce spoilage enzymes cause off-flavors, structural defects and reduced shelf life of milk products. Using four treatments, we determined the best growth protocol for each strain to use in future experiments. Treatment 1: 80 o C heat shock and 32 o C 24hr incubation, Treatment 2: 80o C/ 55 o C, Treatment 3: 100 o C/ 32 o C, Treatment 4: 100 o C/ 55 o C. Our results were as follows: Treatment 1: 25%, Treatment 2: 11%, Treatment 3: 41%, Treatment 4: 23%. We then used these results in Part 2 of the experiment. Part 2 of our experiment characterizes each strain as either positive or negative for proteolytic and/or lipolytic activity. All of the strains tested were proteolytic and about half were lipolytic. Knowing if these strains are able to digest proteins, lipids or both will aid in identification and in determining their role in biofilm formation.


Food Science | Microbiology


Rafael Jiménez-Flores

Lab site

California Polytechnic State University (Cal Poly SLO)

Funding Acknowledgement

This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation. This project has also been made possible with support of the National Marine Sanctuary Foundation. The STAR program is administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU).



URL: https://digitalcommons.calpoly.edu/star/179


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