Using CRISPR technology, a Texas A&M-led team involving (from left) microbiology Ph.D. candidate Kathleen McAllister ’15, biologist Joseph Sorg and senior health major Jennifer Kahn ’18 have developed a new genetic system to rapidly and easily introduce mutations into the Clostridium difficile genome.
C. difficile’s multi-drug resistance and the fact that its spores can live outside the human body for extended periods, Sorg says the bacterium has become the scourge of healthcare settings, where it can spread beyond infected hosts via contaminated bedding and equipment and even healthcare providers and unsuspecting visitors.
Sorg has been working since his postdoctoral days to unlock
C. difficile’s basic science, from its physiology to its virulence. He earned his doctorate in microbiology at the University of Chicago in 2006, the same year the C. difficile genome was sequenced, and since has emerged as one of the pioneers of C. difficile study. A member of the since 2010, Sorg currently works alongside his own students — including study co-authors Kathleen McAllister ’15, who is pursuing her doctorate in microbiology, and Jennifer Kahn ’18, a senior health major — to develop effective antimicrobials and preventative techniques capable of combating the devastating pathogen. Texas A&M Department of Biology Fighting the C. diff bug
“Our CRISPR-Cas9 genetic modification tool, we believe, will greatly impact the
C. difficile field in the advancement of our general understanding of C. difficile physiology and development of novel therapeutics against this pathogen,” McAllister said. “Hopefully, our system will help researchers spend less of their valuable time on making mutants and more on characterizing mutants and understanding how this bug functions.”
To help prove their point, Sorg’s laboratory and collaborators at Tufts University School of Medicine and the University of Central Florida used their CRISPR-Cas9-based system to characterize how
C. difficile uses selenium in its growth. Because selenium is an essential micronutrient in all life, its absence would effectively cripple the pathogen by restricting its ability to grow. Furthermore, understanding such pathways in C. difficile could pave the way for useful approaches for identifying novel antibiotics to target it, in far less time than traditional research methods.
C. difficile samples being studied within the Sorg Lab.
“With the genetic tools currently available to the
C. difficile research community, it takes a considerable amount of time to generate a mutation and requires specific strain backgrounds,” Sorg said. “With our system, it may only take a few weeks and could be applied simultaneously to a variety of C. difficile isolates, including clinical isolates, which is an important advantage.”
The team’s technology allows researchers to easily create deletions in the
C. difficile genome, but Sorg says it cannot achieve subtler mutations in its present form. His lab is working to modify the system to allow DNA to be inserted into the genome to further enhance its efficiency capabilities.
The fact that CRISPRs originally were found in bacteria isn’t lost on McAllister, who sees an entire forest of potential genetic modification promise for the
C. difficile trees.
“It’s possible bacteria that have very poor genetic tools for a particular organism may be acceptable candidates to use CRISPR-Cas9 for genetic modification,” McAllister added. “CRISPR-Cas9 systems as a genetic modification tool have already impacted science as a whole and will certainly continue to do so into the future.”
The team’s paper, “Using CRISPR-Cas9-mediated genome editing to generate
C. difficile mutants defective in selenoproteins synthesis,” can be along with related figures and captions. viewed online
Media contact: Shana K. Hutchins, (979) 862-1237 or
email@example.com; Dr. Joseph Sorg, (979) 845-6299 or firstname.lastname@example.org; or Kathleen McAllister, (979) 845-6299 or email@example.com.