USF St. Petersburg campus Honors Program Theses (Undergraduate)

First Advisor

Dr. David John


University of South Florida St. Petersburg

Document Type


Date Available

October 2015

Publication Date


Date Issued

June 2015


Many current antibacterial agents on the market are derived from compounds naturally produced by bacteria. This experiment was conducted to isolate and assess possible antibacterial strains, namely Actinomycetes, from 50 mL of marine and terrestrial samples collected from nine locations around the St. Petersburg area. The agar plates were prepared with Jensen’s AMM agar and inoculated with bacterial samples which had been diluted by factor 1:100 and heated. Three plates were initially assigned to a sample to test against three laboratory bacteria by the overlay method. Then isolates were selected and inoculated onto TSA and BHI agar plates to test against ten common pathogenic bacteria, or relatives of pathogenic bacteria, by lateral streaking. Overlays were also done for some isolates on AMM agar, and a test was performed to measure inhibition over time. The strains yielded from the terrestrial samples appeared to have far greater effectiveness against the test bacteria than those from the marine samples. One terrestrial isolate in particular showed effectiveness against all ten bacteria, whereas the marine samples showed little to no effectiveness against any of the bacteria with the exception of one. The Gram stains performed for four best terrestrial isolates revealed purple rods, indicating Gram-positive Bacillus species but not Actinomycetes. The strains were identified via DNA extraction, amplification and sequencing, as Brevibacillus choshinensis, Brevibacillus laterosporus, Bacillus amyloliquefaciens subsp. plantarum and Bacillus amyloliquefaciens. Extraction of the unknown compounds with dichloromethane and subsequent IR spectroscopy revealed a similar-looking molecule produced by all four isolates, with amine, arene and ketone or ester groups.


A thesis submitted in partial fulfillment of the requirements of the University Honors Program, University of South Florida St. Petersburg.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.