Unexpected Microbial Life in Glacial Clay Could Offer Antibiotic Solutions

For as long as 14,000 years, the First Nations people of the Heitsuk Nation have made their home along the Central Coast of the Canadian province of British Columbia. Among the territory's inlets, islands, rivers, and valleys lie a clay deposit on the north side of Kisameet Bay, near King Island. For as long as most can remember, the tribe has used the clay as medicine. Now science says microbes that live in that clay may have important antibacterial properties.

The history of the Heiltsuk people is grounded in their traditions, oral history, and archeological finds. Recent excavations on Triquet Island in the Central Coast area support the deep memory of the Heitsuk tribe of its existence in a time even before the construction of the Egyptian pyramids.

But predating the people of the land is the land itself — and its clay. The unusually microbial diversity of the clay is the subject of research published recently in the journal mBio.

Kisameet Clay — New Science About an Old Remedy

Kisameet clay is a finely textured, smooth clay. Like most natural clays, it feels heavy and sticky just out of the ground. The clay is pale gray when dry, and bluish gray when fresh. Relatively speaking, the clay deposit is small, about 42 feet thick and covering less than a mile. This deposit is studded with rounded volcanic pebbles and may have found its present location through glacial movement.

In the mid-1900's, private entrepreneurs took an interest in the clay long used by the Heiltsuk First Nations people. Over time, the clay is known to have been used for digestive ailments, as an anesthetic, used to treat burns and sprains, and for beauty and cosmetic purposes. In recent years, the new owners of the clay deposit, located on lands belonging to the Heiltsuk, have partially funded research by University of British Columbia microbiologist, Julian Davies, Professor Emeritus, to explore the properties of the clay.

Unexpected Microbial Life in Glacial Clay Could Offer Antibiotic Solutions — UBC researchers Julian Davies and Shekooh Behroozian with a bucket of the clay. *Image via University of British Columbia*

Davies was initially skeptical about the company's request. In an interview with The Scientist, he remembers thinking, "This sounds like quackery, a little bit." But, Davies noted, "it's been almost all surprises since then."

With an interest in the biology of small molecules, Davies' lab works often antibiotics, and the isolation of bacteria and bioactivity in natural sources, including plants, soils, and lichens. In research on the clay conducted through his lab, Davies has uncovered surprising findings about the Kisameet glacial clay, a material he once thought dubious. Points of the lab research include:

Tested against multidrug resistant bacteria, the clay displays surprising effectiveness in killing pathogens that are member of the ESKAPE bacteria group, microbes that too often prove fatal to hospitalized patients, because they are no longer sensitive to antibacterial drugs. ESKAPE is the collective term used for resistant bacteria that include Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species.
The team took five vertical cores from the clay deposit at five different locations. In evaluating the microbial populations within the clay, the research team was surprised by the diversity they observed. They note, "The deposit harbors surprising bacterial diversity, with greater than 300 species in most samples."
Using DNA extraction, the clay was found to be home to important bacterial populations, including Actinobacteria, Gallionellaceae, and Paenibacillus.
Study authors note Actinobacteria is a group "known to be rich in antibiotic producing organisms."
The "Gallionella-like iron bacteria" were found in the more shallow core samples, and are associated with corrosion and biofouling in pipes and water systems. Studying the bacteria could shed light on the process, plus, bacteria that oxidize iron could be used in bioremediation.
The study identified types of Paenibacillus that assist with fixing soil nitrogen to promote plant growth.

The microbiome of the Kisameet clay (KC) is unique — and bears future study of how the bacterial communities within the clay act individually and interact to promote its bioactivity. The research notes that despite the identification of bacteria with different properties, they "found no strong correlation between bacterial community type and the activity of the clay." Study authors add:

KC is a very complex natural material, and many different factors may contribute to its unique properties, including the resident bacterial communities… The KC deposit may serve as an environment in which to observe novel chemical and genetic interactions between microbes, to study ecological succession, and to reveal new bacterial types with valuable economic properties.

Laid down by moving glaciers, discovered by the indigenous inhabitants of the land, and explored by modern science, the story of the Kisameet clay deposit tells a tale of geology, anthropology, and now, the sphere of medicine. Future study and refinement of the clay may lend microbes that fight disease and pollution and grow healthier plants. Time will tell.