By Mark Pierpont, Controller, and Scott Grossenbach, General Manager, Subterra
Published: BioTech Magazine
October/November 2000

Imagine working 200 feet underground, as the early miners did years ago, in the copper mine located in White Pine, Michigan. This experience does not have to be left to the imaginations of the employees of SubTerra; but they are not mining in the abandoned copper mine-they are working in America's newest growth chamber. SubTerra, in conjunction with Prairie Plant Systems of Saskatoon, Saskatchewan, has converted an underground mine into a sophisticated, biosecure growth chamber for production of transgenic biopharmaceuticals. It is the blending of agriculture, mining and pharmacy that creates this new opportunity.

The White Pine copper mine suffered the same fate as many mines. Located near Lake Superior in Michigan's Upper Peninsula, the cost of mining rose as the ore body deepened. The mine itself is constructed in room and pillar design, with a floor-to-ceiling height of 8 to 10 feet. The rock formation is primarily shale and the temperature stays at 48 degrees regardless of the seasons-and the seasons in northern Michigan are dramatic! Precisely the features which helped close this mine in 1995 are now perfect elements for accelerated plant growth.

The mine entrance has a large concrete portal, which was designed to accommodate two-way traffic of heavy mining machinery. The portal slopes down at 11 degrees for 780 feet before meeting the bedrock. After travelling through a few turns at various corridors, a high tech growth chamber, nestled in the rock, can be discovered. The size of the current chamber is 3,000 square feet, but the site has over 25 acres available for future expansion.

The mine's room and pillar layout requires the construction of two end walls. The slope of the shaft provides a convenient upper entry to the growth chamber. The entry consists of a set of double steel doors, while the lower exit has a single steel door leading to the lower service bay which holds the plumbing, a back-up electrical generator, and other support systems for the chamber. The lights at the entrance to the chamber appear bright in contrast to the darkness of the mine, but the lights inside the growth chamber are more than 10 times brighter: the 50, one-thousand-watt grow lights cause visitors to reach quickly for their sunglasses as they enter the chamber, despite the fact that they are over half a mile underground.

The bulbs in the grow lights are staggered halide and sodium vapor and the plants respond well to the varied light spectrum. Additionally, the waste heat produced by the high intensity lights is perfect for mixing with the cool outside temperature of the mine. The temperature control system draws the mine air into the chamber and maintains a very comfortable 78 degrees. There is an additional bonus for the plants-the cool mine air has a naturally occurring elevated level of carbon dioxide.

Within the chamber, all components of plant growth can be controlled, which means that acres of highly productive space can be created at the site. Each chamber will have no drought, floods, wind, insects, or any other harsh elements, which could slow growth. All of the plants' energy can be directed toward rapid growth and production. The plants, which are currently in the SubTerra chamber, are producing recombinant DNA proteins to help in the fight against a variety of degenerative diseases.

SubTerra has recently received a contract from Health Canada to produce a glycoprotein B (gB) of human cytomeglovirus (HCMV). This project has the r-DNA protein being expressed in the seeds of tobacco plants. There is a certain irony that therapeutic protein research is being conducted in a tobacco plant. Future applications also include using protein from transgenic tobacco plants in bone marrow cancer treatment.

Health Canada intends to scale up production of HCMV gB in order to: * determine the production potential of transgenic tobacco producing HCMV gB; * assess the concentration of the transgene product in a large scale system; * evaluate the agronomic phenotype of the transgenic plants; and, * purify the gB and perform extensive biochemical and immunological analysis of the recombinant product.

Brent Zettl, CEO of SubTerra, feels that the new company is well positioned to provide services to the leading biopharmaceutical firms. "Prairie Plant Systems has been doing considerable research in Canada over the last eight years. A growth chamber in a mine provides accelerated growth, streamlined permitting, year round growing, and cost effective isolation and security. SubTerra is now prepared to serve the United States market."

Zettl notes that research efforts are often limited by budget and performance requirements and he is convinced that the accelerated growth afforded by the conditions of the chamber addresses both concerns. Plant growth has been documented to be better in the mines than in traditional greenhouses or fields. Additionally, plants have been documented to have augmented sugars, flavours and active principle compounds, raising the possibility that the yield of proteins from the plants may be higher under the chamber's growing conditions. The table below demonstrates the accelerated growth patterns of select crops.

Table 1: Chamber vs. Surface Greenhouse-Comparative Growth Rates Crop Percentage Increase in Growth Rate Over Surface Greenhouse Tobacco >50% Sweet Basil >100% Vanilla >35% Potato >40% Canola >25%

Source: Prairie Plant Systems Company Data

In addition to accelerated growth, biomass yields per square foot for each crop were significantly higher.

The permitting process required for the importing and planting of the transgenic seeds from Health Canada to the SubTerra site has occurred smoothly and quickly. Animal and Plant Health Inspection Service (APHIS) made two site visits and processed the permits after seeing the very obvious high level of biosecurity. US Department of Agriculture experts state that, while growing select crops above ground is feasible, the permitting process takes considerable time and work.

Traditional growing methods are limited by soil conditions and climate. SubTerra's growth chamber allows for year-round growth with uninterrupted growing cycles under completely controlled conditions.

SubTerra's growth chamber has added security advantages. The recent destruction of research plants in nearby Rhinelander and Eau Claire, Wisconsin, by "eco-terrorists" has emphasized the need for industrial security. The physical containment offered by SubTerra is far superior to a greenhouse or an open field. The mine site also is conducive to the protection of intellectual property, especially when high-value crops are involved.

Zettl states, "Our site also offers excellent biosecurity. The chamber is extremely isolated." He points out that there are no insects, birds or other pests in the mine, thus eliminating the possibility of pollen or seed escape. Additionally, plant diseases and pathogens normally carried by insects, birds or pests have no opportunity to infect the plants. In the very unlikely event that transgenic pollen or seed might escape from the chamber, White Pine is not a growing region for any of the crops currently used in genetically engineered plants. Zettl believes that the major components driving the acceptance of an isolated underground growth chamber are: "Biosecurity, safety, public perception, and cost efficiency."

It appears that an old copper mine and a new biotechnology firm have more in common than one might think on the surface. The operations which are deep in the bedrock of the earth require trained people and specialized equipment. Although this environment provides unique challenges, SubTerra has completed the transformation of an underground mine into a sophisticated, computer controlled growth chamber, which grows high-value biopharmaceutical plants in a bio-secure environment.