Seminar: Dr. Barbara MacGregor, UNC-CH

UNC Marine Sciences’ Research Assistant Professor Barbara MacGregor, Ph.D. Seminar Presentation.

Seminar Title: Multiplication is vexation: A genomic perspective on DNA replication and cell division in the large sulfur bacteria

Presenter Affiliation: Department of Marine Sciences, UNC – Chapel Hill

Summary: Bacteria are usually microscopic, but within the class Gammaproteobacteria there is a cluster of unusually large species, some actually large enough to be seen with the naked eye. Other features include large central vacuoles (which contribute most of the size); unusual and sometimes varying morphologies, such as unevenly dividing spheres; and the ability to store sulfur, nitrate, and/or phosphate. These are commonly found near the boundary of sulfidic environments, and make a living by oxidizing sulfide at the expense of nitrate or perhaps other oxidants – hence the name Large Sulfur Bacteria (LSB).

What genetic changes allowed this radiation of large bacteria? From the genome data so far, it appears that many of the usual DNA replication and cell division gene clusters were disrupted and/or lost as the group evolved, and it is not clear yet what has taken their place. Since only one species – probably the least extreme – has been successfully cultivated so far, experimental approaches will be challenging.