pH and Microbial Growth

Topics: PH, Bacteria, Microbiology Pages: 1 (279 words) Published: March 24, 2014
pH and Microbial Growth

Introduction:
Each organism has an optimum environment for growth, which includes pH level. Organisms that grow at near neutral pH levels are called neutrophiles. Those that grow best in acidic pH values are called acidophiles. Others, yet, grow best in alkaline pH values and are called alkaliphiles.

In this lab, each group was assigned an organism, which was then used to inoculate 6 different pH levels.

Materials and Methods:
Followed lab procedure 29, “pH and Microbial Growth” in Benson’s Microbiological Applications: Laboratory Manual in General Biology, 12th edition. My group was assigned the microorganism Staphylococcus simulans. Conclusion:

The plotted data defines Staphylococcus simulans’ optimum pH level to be 8.0. Based on this, I conclude that Staphylococcus simulans is a neutrophile growing best near a neutral pH level. From the results of groups EC-1 and EC-2, Escherichia Coli is a alkaliphile. However, based on the fact that E. coli is gastrointestinal pathogen, it seems more viable to believe that E. coli is an acidophile. Not only can E. coli withstand the acid of the gastrointestinal tract, but it thrives in that environment. The results of groups SU-1 and SU-2 vary too much to draw a verified conclusion. Since Sporosarcina ureae is usually isolated from urea, it could be concluded that Sporosarcina ureae is an alkalophile. There was only one group’s results for Saccharomyces cerevisiae. According to group SC-1’s results, it would seem that Saccharomyces cerevisiae is a neutrophile growing best at a pH level of 7.0. However, since Saccharomyces cerevisiae is a yeast, it would seem that it should be an acidophile. Results may have varied due to variance in procedure, contamination, and time allowed for growth.
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