University of Minnesota researchers studied the microbial degradation of the USS Cairo, one of the first ironclad and steam powered gunboats used in the United States Civil War. Studies of microbial degradation of historic woods are essential to help protect and preserve important cultural artifacts.
Built in 1861, the ship hit a torpedo and sank in December 1862 and was recovered about 100 years later from the Yazoo River. It has been on display at the Vicksburg National Military Park in Mississippi. Although the ship has a canopy cover, it is exposed to environmental elements.
"Continued degradation of this historic Civil War ship is causing serious concerns for its long term preservation. To determine the appropriate conservation efforts, it is essential to understand the current condition of the wood and the microorganisms causing the degradation," said lead author Robert Blanchette, a professor in the College of Food, Agricultural and Natural Resource Sciences.
In collaboration with Claudia Chemello and Paul Mardikian, conservators from Terra Mare Conservation, and the National Park Service, the researchers evaluated the types of decay present, revealed the elemental chemistry of the woods and identified a large diverse population of fungi that were isolated from the ship timbers. Their findings were recently published in the Journal of Fungi.
They found:
- Advanced stages of decay were found in many areas of the ship.
- Although some past wood preservation treatments were applied to the wood, fungi tolerant of these protective treatments colonized over time.
- A diverse group of soft rot and white rot fungi were identified from isolations made from wood obtained throughout the ship. Many of the fungi found appear tolerant of compounds used to treat wood for preservation.
"Wood placed in the environment is subject to microbial degradation. Historic buildings and ships exposed to environmental conditions for long periods of time are especially affected. This study showed that although wood preservation treatments were applied to the historic ship, fungi tolerant of these various compounds found their way into the wood over time, causing decay," said Blanchette.
The researchers suggest that in order to control these tough fungi, it is necessary to control the environment by reducing moisture and exposure to the elements. A new enclosed structure for the ship with environmental control is recommended to halt the deterioration caused by both the preservative tolerant wood degrading fungi and the ship's outdoor exposure.
In addition, more information is needed on the biology and ecology of these fungi. The research team hopes to further study these organisms to better understand their interactions with wood and how to control them.
This research was supported by the USDA Hatch Project and the US National Park Service.
About the College of Food, Agricultural and Natural Resource Sciences
The University of Minnesota's College of Food, Agricultural and Natural Resource Sciences strives to inspire minds, nourish people, and sustainably enhance the natural environment. CFANS has a legacy of innovation, bringing discoveries to life through science and educating the next generation of leaders. Every day, students, faculty, and researchers use science to address the grand challenges of the world today and in the future. CFANS offers an unparalleled expanse of experiential learning opportunities for students and the community, with 12 academic departments, 10 research and outreach centers across the state, the Minnesota Landscape Arboretum, the Bell Museum, and dozens of interdisciplinary centers. Learn more at cfans.umn.edu.
