BS in Biological Sciences
Biological Sciences Department
Pyroprinting is a strain typing method that relies on the simultaneous pyrosequencing of the multi-copy rRNA intergenic transcribed spacer regions of E. coli (Black, et al., 2014). These pyroprints can be used to identify the source of E. coli in the environment. Currently, Cal Poly’s Center for Applications in Biotechnology (CAB) is augmenting the existing E. coli pyroprint library. By pyroprinting the intestinal E. coli of cows, we can quantify the strain diversity present, evaluate persistence, and determine the minimum sample size required for a complete overview of the cow intestinal E. coli population. These pyroprints can then be added to the current pyroprint library to be used for comparison to environmental samples. 504 unique pyroprints from two cows were generated over the course of this study, and from these, we determined that the sample size necessary to capture all of the diversity present in a cow at any given time would be over 300 isolates. The intestinal E. coli population of a cow is almost perfectly even, with most strains only being represented by one or two isolates. There is low persistence between sampling events, and very little transmission between cows. These data suggest that intestinal E. coli diversity in cows will be difficult to completely capture, and is not a prudent use of the CAB’s time or money.