Pseudomonas Isolation and Identification: An Introduction to the Challenges of Polyphasic Taxonomy

The ability to isolate an organism in pure culture from the environment is a manageable task for undergraduate students; the identification of that organism requires integration of both genotypic and phenotypic data and illustrates the challenges inherent in contemporary bacterial taxonomy. In this ten-laboratory period series of exercises, students isolate a strain of Pseudomonas from soil and characterize its biochemical and physiological properties, as well as determine the DNA sequence of its 165 rRNA genes. Integrating these data positions students to defend their classification of the isolate as a new species or as a member of a validly described species. Assessment data demonstrate that both knowledge of and confidence in understanding of the principles of laboratory handling of Pseudomonas and bacterial taxonomy increased following the exercises.