Joris Beld, Ph. D.
Assistant Professor
Department of Microbiology and Immunology

Center for Advanced Microbial Processing

Institute for Molecular Medicine & Infectious Disease
Drexel University College of Medicine

“Utilization of environmental fatty acids by bacteria”

Fatty acids are essential to most living organisms since they are the building blocks of lipids. Consisting of a carboxylic acid headgroup and a hydrophobic tail of 14-22 carbons long, they have unique properties required for membrane fluidity. Bacteria endogenously produce fatty acids by the fatty acid synthase (FAS), a complex molecular machine that uses ATP and acetyl-CoA to make fatty acids in an iterative way starting from 2 carbon units. Fatty acid biosynthesis is energy intensive, and fatty acids are used as energy storage by eukaryotes and some prokaryotes. The break-down of fatty acids through the process of beta-oxidation liberates this energy. Bacteria not only biosynthesize and break-down their own fatty acids, but also take-up and utilize environmental fatty acids. Many can use fatty acids as nutrient source, catabolize fatty acids into ATP and acetyl-CoA units, which then can be used for anabolism. However, some bacteria can utilize environmental fatty acids directly for incorporation into lipids, without the need for catabolism. This process is facilitated through the activity of an acyl-acyl carrier protein synthetase (AasS) which loads fatty acids onto the acyl carrier protein (ACP) of the FAS. By sequence, AasS resembles acyl-coenzyme A synthetases but instead of loading the small molecule CoA, it loads fatty acids onto a protein. Using a combination of unnatural fatty acid supplementation and mass spectrometry we identified an AasS in Vibrio cholerae. In vitro characterization showed that the enzyme can load diverse fatty acids on the FAS acyl carrier protein. The activity of AasS allows V. cholerae to circumvent FAS inhibition by taking up fatty acids from its environment and utilizing them directly. Synthesis of an AasS inhibitor allowed us to show this in living bacteria. Understanding how bacteria utilize environmental fatty acids is crucial, especially with several FAS-targeted antibiotics in the pipeline.

Lecture 5 to 6pm

Beld Laboratory Website

Thank you EPAASM Program Chair Vincent Tam and program committee members for an outstanding 2020-2021 program schedule. Look to this site for the 2021-2022 program schedule, to be updated soon. If you have suggestions for topics/speakers for our monthly program schedule, please contact us. Have a great summer!

September 27, 2021 – 789th Meeting

Joris Beld, Ph.D., Drexel University School of Medicine, “Utilization of environmental fatty acids by bacteria”

Watch Dr Beld’s lecture on our YouTube Channel

October 25, 2021 – 790th Meeting

Georgiana Purdy, OHSU

Watch Dr Purdy’s lecture on our YouTube Channel

November 5, 2021 – 50th Annual Symposium –Register for the Meeting – click here

December 14, 2021 – Philadelphia Infection and Immunity Forum

January 24, 2022 – 791st Meeting

Rebekah Dumm, Hospital of the University of Pennsylvania/Children’s Hospital of Philadelphia
Watch Dr Dumm’s lecture on our YouTube Channel :

February 28, 2022 – 792nd Meeting

Carrie Rosenberger, Genentech

March 28, 2022 – 793rd Meeting

Russell Vance, UC Berkeley

April 25, 2022 – 794th Meeting

Bobbi Pritt, Mayo Clinic

May 23, 2022 – 795th Meeting

Student Chapter Sponsored Meeting
Joshua Chang Mell, Ph.D., Drexel University College of Medicine

June 13, 2022 – 796th Meeting

Norman Willett Memorial Lecture
Carol Bascom-Slack, Ph.D., Tufts University

“Microbiology: Nevertheless, We Persisted”
Amy Cheng Vollmer, Isaac H. Clothier Jr. Professor of Biology, Swarthmore College

5pm – 6pm

During the past 35 years, microbiology has undergone a renaissance. In the mid 1980s, at the very time when PCR was invented and HIV was discovered, microbiology, it seemed, had fallen out of favor. Universities were replacing their departments of microbiology into departments of
molecular biology and immunology. Similarly, grant study sections were shifting focus from microbiology to molecular and cellular biology. It appeared that the glory days of microbiology were fading, and yet, we persisted. Microbiologists already realized, as early as 1977, how diverse Archaea and Bacteria were from one another. But 20 years later, eukaryotic biologists were stunned when the genome of archaeon Methanococcus (now known as Methanocaldococcus) jannaschii was published. At least one third of its genes and proteins resembled nothing in the databases for either Bacteria or Eukarya. Another decade would pass before most general biology textbooks placed the three domains and the tree of life – as we know it – into their pages. Suddenly, departments of microbiology reappeared, in medical schools, as well as schools of agriculture. Microbiologists were being hired into departments in the physical sciences: physics, chemistry, engineering, environmental sciences, geology and astronomy. Jeff Gordon and his colleagues initiated studies that led to the study of “beneficial bacteria’. As if that were not enough to put microbiology back into the headlines, the context of worldwide travel and emerging infectious agents like Ebola and coronaviruses have reinvigorated awareness about viruses and their evolution. We will look back on the past three decades, through the lens of an educator of undergraduate students, on the reemergence of microbiology into a new golden age.

Annual Student Organized Meeting

Keynote Speaker: 5:15 – 6:15 pm

Shantanu Bhatt, Ph.D.
Associate Professor of Biology
Saint Joseph’s University, Philadelphia

“Small regulatory RNAs: big players in the virulence of enteropathogenic E. coli”

Dr. Bhatt studies the bacterial pathogen enteropathogenic Escherichia coli (EPEC). EPEC is a major public health concern in developing countries, where it causes significant morbidity and mortality in infants. The genetic basis for the virulence of EPEC is the locus of enterocyte effacement (LEE). Whereas transcriptional control of the LEE has been well-characterized, post-transcriptional regulation of the LEE has been understudied. So, Dr. Bhatt has focused his career on uncovering how trans-encoded small regulatory RNAs (sRNAs) modulate the expression of the LEE and, thereby, control the virulence of EPEC. He uses a highly interdisciplinary approach by incorporating tools from bioinformatics, genetics, and biochemistry to interrogate and characterize these sRNAs. In addition to bacterial pathogenesis research, Dr. Bhatt is a passionate mentor and teacher. As a professor at Saint Joseph’s University, he teaches students both inside the lab and the classroom.


Student Talks (4:00pm to 5:00pm)

4:00-4:15pm: “Microbial cooperation enhances Clostridioides difficile pathogenesis

Alexander Smith, PhD Candidate in the Zackular lab, University of Pennsylvania Perelman School of Medicine

4:15-4:30pm: “Defining the bacterial and host factors responsible for caspase-1-11-independent cell death during infection by Salmonella enteritidis”

Beatrice Herrmann, PhD Candidate in the Brodsky lab, University of Pennsylvania Perelman School of Medicine

4:30-4:45pm: “Age-associated defects in the adaptive immune response to Clostridium difficile infection impair the development of a protective immune response in the elderly

Matthew Bell, PhD Candidate in the Kutzler lab, Drexel University College of Medicine

4:45-5:00pm: “Microbial-based mechanisms of accelerated wound healing”

Ellen White, PhD Candidate in the Grice lab, University of Pennsylvania Perelman School of Medicine

Student Speakers

Keynote Speaker: 5:15 – 6:15 pm. Shantanu Bhatt, Ph.D.