Detectable Diversity in Serratia and Pseudomonas Strains Found in a Local Environment
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Eighteen S. marcescens, S. nematodiphila, and P. chiororaphis strains were isolated from a 5m x 5m plot of soil on Michigan State University's campus on Pseudomonas Isolation Agar. These strains were all found in one local environment but were all isolated separately to assure they did not derive from the same colony. An array of tests was done on the 18 strains to find if the samples of the same species exhibited any detectable diversity. These tests included measuring the absorbance wavelength of the secreted pigment, testing the bacteria against several antibiotics to detect resistance, measuring the formation of biofilm under several conditions, running two PCR's of the genome to find the presence of exoU and popB, testing the bacterium against fungi, finding the swarming abilities of the bacterium, and isolating plasmids from the bacterium. Testing against the antibiotics revealed several strains that varied in which antibiotics they were resistant to. There were a few strains that could form a biofilm under conditions that not all strains could. Variability in species interacting with one another on a plate as well as one variant in the measuring of the absorbance wavelength of pigment are also among the evidence for a detectable diversity. Although there proved to be many similarities within species and even genus, these experimental differences support the hypothesis that there is detectable diversity, or phenotypic variability, among individually isolated samples taken from one local location.