Date of Award

2018

Document Type

Thesis

Department

Biology

First Advisor

Dr. Ruth Plymale

Second Advisor

Dr. Angela Douglass

Third Advisor

Dr. Barbara Pemberton

Abstract

Bacteria produce antibiotics when they are under stress, including starvation stress. Bacteria were tested under carbohydrate and protein starvation against Bacillus subtilis and Escherichia coli (due to the respective Gram positivity and negativity), in order to check for antibiotic production. The bacteria being tested were isolated by past Microbiology classes and stored in a -80°C freezer in the basement of Jones Science Center at Ouachita Baptist University. These test bacteria were grown on tryptic soy agar (TSA) to produce isolated bacterial colonies. Samples of isolated test colonies were then grown under conditions of carbohydrate starvation (M9 salts agar with 0.1 % glucose and 1 % peptone) or protein starvation (M9 salts agar with 1 % glucose and no peptone) in the presence of Bacillus subtilis and Escherichia coli. After five days of incubation at 28°C, antibiotic production by test bacteria was determined by measuring growth inhibition of B. subtilis or E. coli. Of the 27 bacteria tested, 10 were found to consistently produce the zones of inhibition. Three produced zones of inhibition under all conditions, two did so only under carbohydrate starvation conditions, and none only under protein starvation. Also, two bacteria only responded when grown in the presence of B. subtilis, while no bacteria responded when grown solely in the presence of E. coli.

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