Biophysics & Optics

Overview

SUNY New Paltz Research in Physics & Astronomy

Mentor: Dr. Catherine Herne, Assistant Professor Physics & Astronomy SUNY New Paltz

Conference Paper: ResearchGate Publication Link or at DOI:10.1117/12.2675569

Conference: Frontiers in Optics and Laser Science (FiO+LS) - F23 Talk at the Undergraduate Research Symposium in Tacoma, Washington.

Symposium: Student Research Symposium at New Paltz (2023)

Topics: Bacterial attachment rates, Optical tweezers, predatory bacteria, antibiotic resistance, type IV pili

Conclusions indicate a significantly faster attachment rate than previously determined.

Highlights

Conference Paper

ResearchGate Publication Link or DOI:10.1117/12.2675569

Claire E. O'Connor*, Allyson C. Sheneman*, Megan A. Ferguson, and Catherine M. Herne "Measuring attachment rate of predatory bacteria to prey using optical tweezers", Proc. SPIE 12649, Optical Trapping and Optical Micromanipulation XX, 1264906 (5 October 2023); https://doi.org/10.1117/12.2675569

* Authors contributed equally to this work

Poster

Presentation

Process Summary

Poster from the Student Research Symposium at SUNY New Paltz

Optical Tweezers & Bacteria Attachment Rates

Antibiotic resistance is a growing issue. This project addresses how the predatory Bdellovibrio bacteriovorus may be a useful antibiotic. These predatory bacteria use type IV pili to form an attachment to their prey, Escherichia coli for the purposes of this project. Utilizing optical tweezers, we can position the bacteria to facilitate for these attachments and determine the rates at given time intervals. This allows us to further examine the time it takes for the initial attachment to form. We conclude that the attachment is significantly faster than previously understood, indicating that type IV pili may perform almost instantaneous attachments once in contact with their prey bacteria. We additionally predict that the attachment rates would tend toward zero as the time increments decrease, though further studies at short time intervals are needed.

This process incorporated individually performing every portion of the research: plasma cleaning microscope slides, propagating the bacteria, making the setup as pictured above, utilizing the optical tweezers to measure attachments, and analyzing the data.

Image from the optical tweezers demonstrating the appearance of E. coli and B. bacteriovorus at 5 micrometers

Images at two varying depths retrieved from our optical tweezers. Each demonstrate an Escherichia coli as oblong large rods with an attached Bdellovibrio bacteriovorus indicated by the arrows. The difference is color is based on the focal point of the light as it moves through the slide at varying depth.

A cross-section of the slide layout. The top is the slide, then there is a section sandwiched between tape that reads from top to bottom as Cell-Tak, E. coli, B. bactriovorus. Next is the coverslip that rests on the tape and immersion oil on the opposite side of the coverslip. The slide is facing down as it would be in the optical tweezers.

Cell-tak was used as an adhesive on a plasma cleaned glass slide to attach Escherichia coli. The E. coli were then stationary targets. The Bdellovibrio Bacteriovorus were then captured from their solution in the beam waist of the laser focus. The B. Bacteriovorus were free-floating in solution beneath the cover slip.

Results

The attachment percentages were determined from over 200 trials at 15 seconds, 30 seconds, 1 minute, and 2 minutes. The latter three fell within the margin of error of an approximately 50% attachment rate (possibly based on the orientation of the bacteria's pili) whereas the 15 second trials were distinctly lower.