Sources of Bacterial Species with Antibiotic Activity: Soil & Rotten Wood

We chose to compare two environmental sources of bacterial species, rotting wood and soil to see which of the two would be the best possible source of bacteria that produce antibiotics. We chose to sample from decomposed wood because of the wide range of available nutrients which would allow for higher competition. We believe that decomposed wood will harbor some bacteria that were not found in soil in our previous work. Samples of rotted wood and soil were collected aseptically at numerous sites in six states and the District of Columbia. Bacteria that grew aerobically were isolated and tested for ability to inhibit growth of Escherichia coli, Pseudomonas aeruginosa and/or Staphylococcus aureus. Chromosomal DNA was extracted from the bacteria with antibiotic activity and the 16s ribosomal RNA gene amplified by pcr. The pcr product was sequenced commercially and a BLAST search done to provide a tentative identification of the bacterial isolates. Wood samples varied in percentages of isolates that inhibited growth of these test organisms. The data were analyzed to determine if the rotted wood and soil were statistically different sources of bacteria with antibiotic activity.