Let it Glow - Let it Glow - It Can't Hold it Back Anymore!

gif animation of bacterial petri dishes in room light and in the dark. — The road to microbiology is paved with glowing bacteria. Images by Mark O. Martin www.microbialsupremacy.com

At first, the room is pitch black. My eyes adjust to the darkness and I see two eerie blue-green glowing columns of plastic petri dishes stacked on a table. “Ready? Hold still for 15 seconds”. Click…..click. “Lights”. So began the first #LuxArt portraiture session at the American Society for Microbiology Conference for Undergraduate Educators (ASMCUE) with Dr. Mark O. Martin, University of Puget Sound. Glowing bacteria? Photography by bacterial light? The eerie glow is from a highly bioluminescent, non-pathogenic strain of bacteria Photobacterium leiognathi KNH6 . First collected from K āne ʻohe Bay, O’ahu Hawaii by Dr. Ned Ruby, University of Hawaii and Dr. Eric Stabb, University of Georgia, this nonpathogenic bacterium is unusually bright, produce enough light that you can read by it. Bacterial candlelight, as it were. Outshining its cousins Vibrio sp., Photorhabdus luminescens, and Pseudomonas, scientists are unraveling P. leiognathi’s glowing super power.

Twinkle, twinkle *Photobacterium*. Lux Art by Andrew Iverson

Photorhabdus leignothi was first isolated in waters of Hawaii. Lux Art by Rohini — *Photobacterium leiognathi* was first isolated in waters of Hawaii. Lux Art by Rohini

Painting with glowing bacteria. What better way to get students anyone excited about microorganisms? Dr. Mark O. Martin, a self-proclaimed “Microbial Supremacist” uses glowing bacteria to entice students to explore the mysteries of microbiology. Now fellow microbiology educators at ASMCUE created #LuxArt and had #LuxSelfies made. “Doc” Martin was first captivated by bioluminescence as a young boy. His infectious excitement and boyish glee for teaching others the wonders of bacteria led to fusing of art and science in the classroom. Students in Doc Martin’s Microbiology course use P. leiognathi for #LuxArt art shows. The professor himself takes it one step further making #LuxArt Christmas tree decorations – Merry LuxMas everyone. Of course, glowing pumpkins for Halloween is an essential trick and treat. Like the bioluminescent lure of a deep sea Angler Fish, Dr. Martin and his glowing bacteria attract students to the wonders of microbiology. His alternative teaching methods certainly seem to inspire students to see the world with “microbial colored glasses”, as one student cartooned. With P. leiognathi Dr. Martin wants students to understand that this microbe is not unique in making light, but it is unique that it is free-living in the ocean water and is always making light.

2016_ASMCUE_MOMartin — Dr. Mark O. Martin illuminated by stacks of Photobacterium leiognathi #LuxArt plates made by ASMCUE participants.

Other Glowing Bacteria

Most of light-producing bacteria known live in or on fish, squid, round worms, insects and plant roots. One of the best understood interactions with P. leiognathi’s cousin, Vibrio fischeri, and bobtail squid. In that case, the bacterium is located in a specialized light organ in the squid’s head. At night, the bacteria produce light which acts as a cloaking device for the squid. On a moon-lit night, the squid swimming in the ocean surface waters casts a shadow making it easy for predators like * and * to find their squid snacks. The bacterial flashlight provides a light “cloaking device” so no shadow is seen. For more details read the graphic novel “The Squid, the Vibrio and the Moon”. The Howard Hughes Medical Institute education group, BioInteractive, has excellent videos about the squid-Vibrio system. Additional resources are listed at the end of the post.

V. fischeri and most bioluminescent bacteria is that they only grow when their numbers are high enough. Bioluminescence is controlled by a chemical that these bacteria put out into their environment. When there is enough of the chemical, a set of genes are turned on, and the chemical that makes the light is produced. P. leiognathi is different – it makes the same chemicals for bioluminescence, but the chemicals are always being made. The genes are never turned on and off. Making light constantly is an energetically expensive activity, so why does P. leiognathi do this? The bacterium’s light is at the proper wavelength to be seen in the ocean waters. Is it attracting an organism we don’t know about? Is the light an seemingly expensive waste product? Like so many exciting questions about microbes, why this free-living bacterium doesn’t regulate its light production remains to be answered. Certainly, the intense glow of this environmental microbes continues to lure in students and scientists alike and spreads a broader appreciation for the amazing world of microbiology.