As you may or may not remember from the previous post, for a couple days during the Civil War, some soldiers had wounds that glowed in the dark. No one knew why wounds were producing light, so the the phenomenon got nicknamed “Angel’s Glow.” Even though glowing Civil War soldiers was a pretty bizarre thing to happen, after the Civil War, when there was no internet and people had a lot of other things to worry about, just about everyone forgot about “Angel’s Glow”, except Civil War buffs (for some reason, if you’re really into the Civil War, you get called a “buff,” but if you’re really into just about anything else, like science, music, comedy, etc., you get called a “nerd”).
One such Civil War buff was a 17-year old high school kid named Bill Martin. Unfortunately I couldn’t find a photo of Bill so, instead, here is a photo of me at age 17 in high school, just in case you weren’t sure what 17-year-olds typically look like:
Bill heard about “Angel’s Glow” about 15 years ago while touring the Shiloh battlefield in Tennessee. He came up with a hypothesis (a reasonable guess) that, maybe, the glowing was caused by microbes. Most Civil War buffs probably don’t think about microbes on a regular basis, but Bill often thought about them because his mom, Phyllis, was a microbiologist (a scientist who studies microbes). Bill knew his mom studied some bacteria that lived in the soil and that were able to glow in the dark. Bill talked to his mom about his hypothesis and she suggested that Bill and his friend Jon Curtis do a scientific study to see if it was likely that microbes in Shiloh, Tennessee could cause wounds to glow. (My mom, who was a piano teacher, would probably not have helped me reach the same conclusion, though if the soldiers’ wounds were mysteriously playing piano music, we probably would have wiped the floor with Bill and Phyllis).
Bill and Jon did experiments and research and determined that a bacterium called Photorhabdus luminescens probably made the soldiers’ wounds glow. (Photorhabdus luminescens is the bacterium’s scientific name [i.e. the name scientists all over the world call them]. As far as I could find, this species of bacteria does not have a common name [i.e. the names non-scientists call them], which is not unusual for bacteria. Microbes rarely are popular enough to get common names, probably because non-scientists usually can’t see them and/or don’t know they actually exist and/or think all microbes are jerks.) Photorhabdus luminescens are the things that look like Mike and Ikes in this microscope photo:
Photorhabdus luminescens are bioluminescent, meaning they are living thing that can make their own light (like fireflies and lanternfish). Scientists haven’t figured out exactly why being able to glow helps these bacteria, but one thing the scientists do know is that Photorhabdus luminescens hang out with a type of microscopic worm called soil entomopathogenic nematodes, which are tiny worms that look like this:
The nematodes and the bacteria are partners, kind of like Batman and Robin, but instead of working together to fight crime, they work together to eat insects.
The nematodes carry the glowing bacteria in their guts, like this:
The bacteria stay in the nematode’s gut until the nematode is able to get inside an insect it wants to eat. The nematode then releases the glowing bacteria into the insect’s blood, which make the insect start glowing, like the infected waxworms in this photo:
Not only do the bacteria make the insect glow, they also release toxins in the insect’s blood that:
- kill the insect.
- break the insect’s body down into nutrients that the nematode can then eat.
- kill any other microbes that invade the insect’s body before the invaders eat the insect that the nematode and the Photorhabdus luminescens worked so hard to turn into food.
As gross as all that sounds, those toxins are probably what saved the glowing Civil War soldiers’ lives. The soldiers were too big for the Photorhabdus luminescens toxins to hurt them, but the toxins would have killed the other bacteria in the soldiers’ wounds, which prevented the wounds from becoming infected. This would explain why the glowing wounds healed better than non-glowing wounds.
The high school kids Bill and Jon figured this all out. The only problem with this explanation is that Photorhabdus luminescens can’t survive in the temperatures typically found inside a human body. But, Bill and Jon were able to find a solution to this problem too and were able to win an international science fair competition with their findings. How? Read my next post to learn the answer.
To learn more about bacteria and other microbes, read my free eBook Where Wild Microbes Grow.
To learn more about bioluminescence, read my book A Day in the Deep.
Online References and Resources:
AAAS ScienceNetLinks. "Glowing Wounds."
Mental Floss. "Why Some Civil War Soldiers Glowed in the Dark." Article by Matt Soniak.
Microbe Wiki. "Photorhabdus luminescens."
The National Center for Biotechnology Information. "The lumicins: novel bacteriocins from Photorhabdus luminescens with similarity to the uropathogenic-specific protein (USP) from uropathogenic Escherichia coli."
USDA. "Students May Have Answer for Faster-Healing Civil War Wounds that Glowed."
Photos and Images:
Click the photos, images and GIFs used above to find their sources. If the photo does not have a link, it was taken by Homer High School's senior photo photographer in 1988.