A friendly fungus: A few genetic tweaks can turn Aspergillus niger into an enzyme factory. (©BA SF)
Silent Green
Pop quiz: What three categories of biotechnology products can provide the greatest environmental benefits? Most readers, even those inside the industry, will think of only two answers: biofuels, which substitute biomass for fossil-fuel feedstocks, and genetically engineered crop plants, which can substantially reduce pesticide use. But what about industrial enzymes? If that didn’t spring to mind, don’t feel bad. Industrial biotechnologists are accustomed to obscurity. "You could say our technology is kind of the software behind many production processes, or silent products—consumers don’t see [them], but they contribute to diminishing the environmental footprint," says Steen Skjold-Jørgensen, vice president for research and development at Novozymes North America in Franklinton, N. C.
The impact of these little known but shockingly ubiquitous products is enormous. According to a recent life-cycle analysis, the enzymes from Skjold-Jørgensen’s company alone reduce global carbon emissions by about 28 million tons, roughly equal to the commitment Denmark has made for carbon dioxide reduction under the Kyoto protocol.
Cool And Clean
Typically a customer will approach an enzyme maker with a specific problem. "Our approach would be to define the unmet needs of the marketplace, then to screen our libraries for the best candidate enzymes, and then to make modifications to those to improve the performance along the targeted dimension," says Janet Roemer, executive vice president of the specialty enzymes unit at Verenium in Cambridge, Mass.
Each enzyme maker has its own library of potentially useful enzymes. For Verenium, the library comes mainly from extremophiles, microorganisms that live in harsh environments where not much else can, which were collected on various bioprospecting expeditions by corporate ancestor Diversa. Novozymes, meanwhile, relies on a wide range of fungal, bacterial and other enzymes for its screening campaigns.
Although the environmental benefits are a selling point, most industrial customers only adopt an enzymatic process if it also improves their bottom line. Several years ago, for example, Novozymes began working with laundry-detergent manufacturers to solve a problem in their supply chain. "The detergent producers of course [were] interested in kind of decoupling their ingredient purchases from the oil prices in the Middle East," Skjold-Jørgensen says. Substituting stain-removing enzymes for some of the fossil fuel–derived surfactant compounds in the detergents accomplished that. At the same time the detergents became friendlier to the environment. "You can actually accomplish stain removal, cleaning, maintenance of your fabric with these biocatalysts at lower temperature than you would normally do. That of course has a bearing on the environmental impact," Skjold-Jørgensen says.
As newer washing machines with lower wash temperatures come on the market, each household uses a little less energy with each load of laundry. It’s not much individually, but the aggregate effect will be huge. According to Skjold-Jørgensen, if most consumers in Europe could turn down washing-machine temperatures by 10 degrees, it would save two power plants worth of energy.
Working For Chicken Feed
Reducing carbon emissions, however, isn't the only way to improve a product's environmental profile. For instance, Verenium's top-selling product, Phyzyme, attacks phosphorous—a different but equally insidious pollutant.
Phyzyme is a phytase enzyme. "It's used in the animal-feed market to unlock the phosphorous that's in the grains in chicken and pig feed, because that phosphorous gets all tied up in the plant phytate, and so the phytase comes in and it really makes it available to the animal," Roemer says.
Before purified phytase was available, farmers had to overload the feed with inorganic phosphate to meet the animals' dietary needs. Inorganic phosphate isn't metabolized as efficiently as plant phosphate, so 70 percent of the mineral ended up in the animals' feces—wasting the farmers' money and leading to eutrophication of nearby waterways. Phytase-spiked feed is much more efficient.
Other companies also produce phytases, but Verenium took pains to build some unusual characteristics into theirs. "The product was developed to be active in the pH of the upper gut of the animal and deactivated as it passed through the digestive system, so it does what it's supposed to do just in the right place in the animal's digestive system," Roemer says. Phyzyme is also thermostable, so it can be compressed into pellets. Feed-producing giant Danisco now incorporates the enzyme into standard chicken and pig chows.
Besides cleaning up manure and lowering laundry temperatures, industrial enzymes reduce pollution in a wide range of other businesses, including leather tanneries, commercial bakeries, paper mills and oilseed-processing plants. Eventually maybe they'll even make it into a newsroom.
