Investigating the prevalence, evolution and phenotypic characteristics associated with Geobacillus and Parageobacillus plasmids

Bhoolia, Hena
Journal Title
Journal ISSN
Volume Title
Plasmids are extrachromosomal elements that are commonly harboured by bacteria. They are a source of unique genes that influence the diversity and phenotypic characteristics of bacteria and are also widely utilized in a vast number of biotechnological applications. The genomes of several Geobacillus and Parageobacillus strains are observed to incorporate plasmids, however, only a few preliminary studies have highlighted the characteristics of some Geobacillus plasmids. This study aimed to investigate the prevalence and diversity of plasmids among the geobacilli, analyse their evolutionary dynamics and identify plasmid-encoded phenotypes that may be of biotechnological value. Here an exhaustive set of Geobacillus and Parageobacillus genomes were analysed to identify plasmid DNA and used comparative genomics to gain insight into their evolutionary dynamics. 56 plasmids were identified and grouped in nine distinct plasmid groups, indicating extensive genetic diversification of the plasmids of these genera. Furthermore, plasmids were functionally annotated to assess their biological roles among the geobacilli. From there is evidence of a range of potential phenotypes and possible thermostable proteins/enzymes that make these plasmids valuable candidates for biotechnological purposes. Lastly, plasmid DNA extraction and curing of selected Geobacillus and Parageobacillus strains was carried out to determine phenotypic differences between plasmid-cured and wild-type strains, this was unsuccessful attempt and may be as a result of possible low copy number plasmids as well as ineffective lysis of bacterial cells
A dissertation submitted in fulfilment of the requirements for the degree Master of Science in Molecular and Cell Biology in the Faculty of Science, University of the Witwatersrand, Johannesburg, South Africa, 2020