Overview

Using Acinetobacter baylyi ADP1 to Detect Pathogenic DNA

The UT Austin iGEM team has embarked on a mission to protect the Texas Hill Country’s beloved bat population. In the last fifteen years, White Nose Syndrome (WNS) has threatened North American bats, killing over 6 million bats and wiping out entire regional populations. In 2020, the first signs of this infection were detected in the Texas Hill Country, threatening bats that live under our iconic Austin Bat Bridge on Congress Avenue. Current methods for detecting Pseudogymnoascus destructans, the fungal organism that causes White Nose Syndrome, require advanced lab equipment and techniques. Within the United States, only three labs are qualified to perform these procedures.

The UT Austin iGEM team is tackling the challenge of detecting WNS using Acinetobacter baylyi ADP1, a bacterium capable of taking up DNA directly from the environment (eDNA). Our design, ADP1 Recombination and Recognition of WNS eDNA (ARROWE), utilizes Acinetobacter baylyi ADP1’s powerful and flexible genetic capabilities to detect P. destructans. Our project uses a kill-switch negative selection mechanism and a yellow fluorescent protein (YFP) screening system to confirm the uptake of P. destructans eDNA. Therefore, cells that do not uptake the P. destructans eDNA should die, while those that do should fluoresce yellow. This biosensor provides an efficient alternative for detecting White Nose Syndrome to help us better understand the severity, range, and origins of the pathogen, P. destructans. Additionally, we demonstrate to the iGEM synthetic biology community Acinetobacter baylyi ADP1’s powerful capabilities.

Why Bats?

Bats play an important role in pollinating plants, dispersing fruit seeds, and providing nutrients for other cave animals. Experts estimate that bats save American farmers approximately $3 billion every year by killing pests and reducing pesticide usage in the agriculture industry. Bats provide significant positive impacts on the global ecosystem and economy.

Local People Solving Local Problems Using Synthetic Biology

On any given summer evening in Austin, Texas, hundreds of people gather near the Congress Avenue Bat Bridge, where urban society seamlessly intersects with nature, to watch the nightly bat show. Each night, tens of thousands of bats fly out from under the bridge as they begin hunting for their prey. The Congress bridge is home to the largest urban bat population in North America. These tiny little critters play an important role in maintaining the pristine beauty of the Texas Hill Country. Although you may think of tacos and music when you think of Austin, our culture has been deeply influenced by the famous Congress Avenue Bat Cave. In 1996, a minor league ice hockey team moved to Austin and adopted the name, “The Austin Ice Bats.” Even the mascot of our local community college is the riverbat! The UT Austin iGEM team presents a synthetic biology tool that can be used to protect an animal that has influenced so much of Austin culture.

Fig. 3. Bats take flight in Austin, TX, taken by Sai Senapathi.

Dr. Nate Fuller and Jennifer Smith-Castro, two local White Nose Syndrome experts, have explained to us why urgent action is needed to reduce the potential devastation caused by White Nose Syndrome. Austin’s rich and diverse bat population, including species such as Myotis velifer and Perimyotis subflavust, are most at risk as they hibernate and live in cave-like environments. Data collected from our system can be used to identify infected areas on a national scale. Faster detection of P. destructans will assist scientists in stopping the spread of White Nose Syndrome across the world.

Why ADP1?

Our model bacterial strain, Acinetobacter baylyi ADP1, has powerful and flexible genetic capabilities as a model organism in synthetic biology studies. One important synthetic tool includes the uptake of foreign DNA through the high frequency of natural transformation [2]. Recently, Cheng et al. developed a cell-based DNA sensor by engineering the naturally competent bacterium, Bacillus subtilis , which could identify major human pathogens and the presence of other species in a microbial community [3]. Furthermore, ADP1 has been shown to detect tumor DNA from colorectal cancer cells in vivo [4] and detect ancient DNA from a 43,000-year-old woolly mammoth bone [5]. Previous works demonstrate how naturally competent bacteria, such as B. subtilis and A. baylyi, show promise as biosensor systems to detect foreign DNA. However, further work on the application of ADP1 as a biosensor remains to be completed to build a consistent framework to detect foreign DNA.

We created a strong foundation for detecting environmental DNA and developed the groundwork for an ADP1-based pathogenic biosensor. Beyond iGEM, we hope that conservation organizations like Texas Parks and Wildlife will be able to use our system to curb the spread of White Nose Syndrome and other diseases that threaten bat populations.

References