Comparing the Effect of Different Peptone Media Formulations on Growth of Various Strains of Escherichia coli
Enzymatically Hydrolyzed proteins are commonly used in media formulations to provide a rich source of complex nitrogen, carbon, peptides, carbohydrates, and amino acids necessary to provide reliable growth of microorganisms.
As media formulations have evolved, so have requirements for nitrogen sources to be animal free, kosher, non genetically modified, and allergen free solutions. Based on several protein sources, a variety of commercial peptones have been developed.
Along with the variation in composition of these peptones comes the question of performance: What effect does using these different peptones have on bacterial growth?
Methodology: Cultures were grown in liquid media using the various peptones obtained from Nu-tek Bioscience in their formulations, with amounts based on the total percent nitrogen. During this time, the absorbance at 600 nanometers of the cultures was monitored at certain time intervals using a spectrophotometer. This allowed for the data to be plotted and compiled into comparative growth curves.
- Some strains are harmless, some pathogenic , and can cause illness or even death, along with strains developed for lab use.
- Easily culturable, genes are easy to manipulate, and has a well documented genome
For 100 mL Media:
50 mL 0.2% total N Peptone solution
20 mL 5x M9 Salts
5 mL 10% Glucose
25 mL Sterile Nanopure Water
Each component is sterilized separately using an autoclave on liquid cycle for 35 minutes.
|Peptone Amino Nitrogen and Total Nitrogen:|
|Peptone||% TN||AN/TN Ratio|
|Soy Nu-tek HSP-A||7.6||0.41|
|Soy Competitor 1||9.2||0.21|
|Soy Competitor 2||9.2||0.25|
|Soy Competitor 3||10.2||0.24|
|Pea Nu-tek HPP-A||12.4||0.40|
|Nut-tek Soy-YE A||9.1||0.48|
|Nut-tek Soy-YE B||8.1||0.42|
|Nut-tek Soy-YE C||8.9||0.46|
|Amino Acid Comparison|
|Nu-Tek Soy 1 Peptone||Nu-Tek Pea Peptone|
|Amino Acid||Free (mg/g)||Total (mg/g)||Amino Acid||Free (mg/g)|
|Aspartic Acid||6||45||Aspartic Acid||14|
|Glutamic Acid||15||85||Glutamic Acid||2|
- Nu-Tek Soy HSP-A media formulations resulted in the highest optical density across all strains of E. coli
- Nu-Tek Pea grew to a significantly lower OD than Nu-Tek Soy across all strains
- When Nu-Tek Pea was mixed with a lesser quality peptone, it raised the comparative growth levels of the competitor to an OD that was similar to Nu-Tek Pea.
- The addition of yeast extract in a 1:1 blend with Nu-Tek Soy appeared to improve the media, but the difference wasn’t significant
BD Bionutrients Technical Manual. 3rd ed. N.p .: Beckton, Dickenson, 2006.
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Rasko, D. A., Rosovitz, M. J., Myers, G. S., Mongodin, E. F., Fricke, W. F., Gajer, P., … & Ravel, J. (2008). The pangenome structure of Escherichia coli: comparative genomic analysis of E. coli commensal and pathogenic isolates. Journal of bacteriology, 190(20), 6881-6893
Jennifer FitzGerald, Maddy Riemenschneider, Hailley Cound, Thomas C. Marsh, Ph. D Chemistry Department, University of Saint Thomas, St. Paul, MN