Biology ETDs


Kevin Crown

Publication Date



Bacteriophages are viruses that infect bacteria, which have been used to treat bacterial infections in people for decades. They are also now being used as FDA approved preservatives as a means to prevent the growth of spoiling bacteria in many ready-to-eat foods. Bacteriophages tend to infect a very narrow range of bacterial hosts, some only a single sub-strain. When used for therapeutics or food treatment however, it is desirable to use phages that are promiscuous in their host range. This has led to attempts to broaden the host range of the most useful phages. By passaging phages in co-cultures of their natural host with increasing ratios of a target-host, we were able to expand the host range of two phages specific to Clostridium sporogenes. This adaptation was performed in both the presence and absence of a mutagen. Of twenty-eight total mutants, six were sufficiently stable to persist in target-host culture alone. Of these six, four were chosen for further analysis of their infective activity in their natural and target hosts. Most phage populations that resulted from each passage of each co-culture infection lost infective activity against their initial host and also failed to show infecting activity in the target-host. On the other hand, there were several phage populations that demonstrated a gain of activity against one or both hosts. In some cases the gained infectivity exceeded the infective activity that was measured for the starting host at the beginning of the project. Though mutations causing host-expansion events in phages seem to occur randomly, there was a notable increase in the number of successful mutations in the presence of a mutagen as opposed to without.

Project Sponsors

Sandia National Laboratories




phage, bacteriophage, clostridium, sporogenes, microbiolgoy, virology, 17886, 7955

Document Type


Degree Name


Level of Degree


Department Name

UNM Biology Department

First Committee Member (Chair)

Hofkin, Bruce

Second Committee Member

Santarpia, Joshua

Third Committee Member


Included in

Biology Commons