banner by Sarah Burns

Did Civil War Soldiers Glow in the Dark?

by Jill McDonnell

It was early April 1862, but the normally pleasant fields of southern Tennessee were anything but lush and inviting. It had been almost a full year since the Civil War began, long surpassing most expectations for a clean and quick battle. As the Battle of Shiloh continued over two days, Union forces drove Confederate soldiers even further south, resulting in one of the bloodiest conflicts of the war. Short on medics and field transport, thousands of wounded soldiers lay in the mud and rain for days until help could arrive.

But it was during these treacherous nights that passersby reported a strange sight: several soldiers’ wounds were glowing. Even stranger, the soldiers with glowing wounds seemed to have a better survival rate than those without the glow, giving rise to the nickname “Angel’s Glow.”

This mystery remained unsolved for well over a century, until two teenage boys completed a high school science fair project in 2001. With the help of his microbiologist mother studying the blue-glowing bacterium Photorhabdus luminescens, Bill Martin, along with his friend Jonathan Curtis, conducted their own experiments to investigate if P. luminescens was the source the soldiers’ life-saving glow.

While doing some background reading, the friends learned that P. luminescens resides symbiotically in the intestines of nematodes, parasitic worms which provide the glowing bacteria with a place to live and eat. In return, P. luminescens nourish and protect nematodes by killing threatening microorganisms. Feeding on insect larvae, nematodes seek out suitable larval hosts and invade larval bloodstreams. Then, the nematode regurgitates the P. luminescens bacteria, which releases toxins and enzymes to decompose the larvae’s body, supplying nutrients for both the bacterium and nematode. Once the nematode reproduces with its “puker-in-crime” still inside, the pair sets forth to conquer more territory, akin to the Confederate and Union armies.

Despite its comfort in larval bodies, scientists have long dismissed P. luminescens’ potential habitability within humans, believing that man’s higher body temperature would be inhospitable for the bacterium. But Martin and Curtis dug deeper into historical records and found that spring nights in Tennessee would have been cold enough to induce hypothermia for impaled soldiers lying on the swampy land. With adequate soil conditions and body temperature, P. luminescens found its own little army base to comfortably snack on dirt-infested battle wounds.

Martin and Curtis also explained P. luminescens’ life-preservation qualities. In addition to toxins, the nematode-housed bacteria release antibiotics to fend off rival bacterial or fungal competitors. By suppressing foreign microorganisms, P. luminescens limited local and systemic infections that frequently led to death in Civil War soldiers.  This antibiotic chemical — 3,5-Dihydroxy-4-isopropylstilbene — induces apoptosis, a process nicknamed “cell suicide” that limits excessive cell growth and division.

As Kumar, Nambisan and Kumar et al.’s 2013 study suggests, P. luminescens’ apoptotic chemical makeup is also a double-edged sword in our current fight against cancer. Warding off metastasis, the study showed that the antibiotic incites self-destruction in human cancer cell lines in vitro. Moreover, 3,5-Dihydroxy-4-isopropylstilbene functions as a powerful antioxidant, scavenging DNA-damaging free oxygen radicals. If left unchecked, these hyper-reactive oxygen molecules play a role in cancer formation, Alzheimer’s disease and the aging process.

Based on their research, Kumar, Nambisan and Kumar et al. hope to harness P. luminescens’ disease-prevention properties to create less toxic, more natural antioxidants for the pharmaceutical industry. Recently, there has been a push to find natural antioxidant sources as more consumers demand healthier, safer and cheaper alternatives to chemical concoctions in drugs and even cosmetics. Furthermore, utilizing biological metabolites in future drug therapies would drastically reduce the negative side effects of chemotherapy and radiation.

Whether searching for the next cancer killer, writing a historical non-fiction or even creating a school science fair project, everyone can learn something from the curious tale of the glowing Civil War soldiers. Who says you can’t learn anything useful in history class!