Document Type


Degree Name

Master of Science (MSc)



Program Name/Specialization

Integrative Biology


Faculty of Science

First Advisor

Dr. Gabriel Moreno-Hagelsieb

Advisor Role



As new techniques have been introduced, specifically the possibility of complete genome sequencing, better methods of defining bacterial species have also been proposed. One of the most recently proposed methods, using bioinformatic techniques, is to calculate the average nucleotide identity (ANI) between the homologous genome segments of different isolates. Another method for species discrimination that has been tested successfully is the similarity of DNA compositional signatures. However, in a recent update, DNA signatures split the available Escherichia coli complete genomes into three groups. To check if this result was consistent with such genomes belonging to different species, we tested methods based on genomic composition and compared them to classic homology methods. The five methods used were ANI, DNA signatures, 16s rRNA, 23s rRNA, and genomic similarity score. All species discrimination methods grouped genomes of E. coli slightly differently. However, the DNA signatures and ANI split the groups similarly, suggesting that methods of delimitation based on genetic composition are just as effective as methods based on homology.

Convocation Year


Convocation Season