Earth Rx: A microbial biotechnology prescription for global environmental health

Water. Waste. Energy. This trio of problems is among the greatest challenges to the environmental health of society. Water purification alone is becoming more problematic in the world due to our increasingly reliance on contaminated sources, such as polluted rivers, lakes and groundwater.

“All of these issues are closely interrelated,” says Bruce Rittmann, director of the Center for Environmental Biotechnology in the Biodesign Institute at ASU. “For example, most of the pollution wastes that we worry about are really just energy put in the wrong place and causing trouble.”

It was to address these challenges that Rittmann, along with a group of international colleagues, gathered at a symposium held at ASU last April to work on a roadmap for biology-based solutions to turn these threats into opportunities. The culmination of the workshop was a paper published as the cover story in the latest issue of Environmental Science & Technology (http://pubs.acs.org/subscribe/journals/esthag/40/i04/html/021506feature_rittmann.html).

Their solution: a synergistic marriage of two distinct disciplines, microbial ecology and environmental biotechnology. “Together, they offer much promise for helping society deal with some of its greatest challenges in environmental quality, sustainability, security, and human health,” Rittmann stated in an excerpt from the paper.

For the majority of Earth’s 6 billion year history, microbes ruled, spreading to every nook and cranny on the globe, from geothermal vents on the ocean’s floor to arctic permafrost. Now, uncovering and categorizing this abundant biodiversity is one of the chief goals of scientists in the field of microbial ecology – and may be the key to helping the planet –by putting these rich microbial communities to work to help serve the needs of society through environmental biotechnology.

Leading the marriage are revolutionary changes in compiling vast amounts of genetic information on microbial organisms through state-of-the-art DNA-based techniques. Identifying just a single microbial specimen is a daunting task, considering, that there may be trillions of bacteria in every liter of water.

“We have hardly begun to tap the potential that is already provided by nature,” said Rittmann.

The beginnings of microbial ecology started back in the 1940s and 1950s, when microbial cultures were initially sorted by size and shape. Before the modern DNA-based techniques, the function of a microorganism was assigned by selective culturing on agar plates or a nutrient-rich broth and selecting on the basis of metabolic function, which turned out largely to be a hit-or-miss approach.

“You would find a few organisms that just grew like crazy,” said Rittmann. “We call them ’weeds’ because they take advantage of the luxurious conditions found in the lab but they might not be the ones who are important out in the real world, where it isn’t so luxurious.”

To aid in the identification and function of individual microorganisms and communities, the first use of modern molecular biology tools began in the early 1980s, with the advent of polymerase chain reaction (PCR) amplification of microbial DNA and a new view of the evolution of organisms based on their ribosomal RNA.

These technologies have advanced into high-throughput genomic and proteomic protocols that can detect specific genes and their metabolic functions with great precision and detail. Other methods can now reconstruct entire genomes of what were once “unculturable” microbes.

Rittmann refers to this early period as a “profitable stamp collecting” approach – “absolutely vital in providing a cathedral foundation of knowledge; yet we now need to focus more on utilizing this knowledge.”

Enter the field of environmental biotechnology. Environmental biotechnology has been around for almost a century, first adapted widely in the 1910s and 1920s when wastewater was cleaned up by a bacterial-laden sludge that speeds up the breakdown of the organic material in sewage.

With recent advances in biology, materials, computing, and engineering, environmental biotechnologists now are able to use microbial communities for a wealth of services to society. These include detoxifying contaminated water, wastewater, sludge, sediment, or soil; capturing renewable energy from biomass; sensing contaminants or pathogens; and protecting the public from dangerous exposure to pathogens.

Rittmann’s center puts some of these technologies into service, identifying microorganisms that help clean up pollutants such as trichloroethene (TCE) and perchlorate from the water supply and generating electricity from wastewater.

“Scientifically, it might be easiest to let the microbes convert the energy is organic wastes directly to electricity. However, they also can generate useful fuels, such as methane and hydrogen, and we are pursuing research on all of these renewable-energy forms.”

Rittmann believes the key to achieving success through microbial ecology and biotechnology is to take advantage of microbial diversity as much as possible, particularly having different microbe to perform the same role. “It usually isn’t just one organism, a superbug or magic bullet,” says Rittmann. “Instead, the best results require a community of microorganisms.”

Rittmann is motivated by the huge benefits that environmental biotechnology and microbial communities can bring to society. “I think if we could succeed in capturing the energy out of waste materials, this would be a world-transforming technology and a real step forward to using more renewable forms of energy and much less reliance on fossil fuel.”