Applications of Industrial/White Biotech

• Introduction

Modern biotechnology is a powerful and versatile tool which can compete with chemical and physical means of reducing energy and material consumption and minimising the generation of waste and emissions.  There is general agreement that the use of biotechnology in industry does not simply remove pollutants but also will prevent pollution at the source.  Efforts to achieve clean industrial products and processes will also bring great benefits to industry over the next ten or twenty years.  Industrial biotechnology, using microorganisms and biological catalysts (enzymes) to produce goods and services, has come of age.

• Biotechnology in industrial sectors

Various parts of the industry are experimenting with the new tools offered by biotechnology. Of particular interest is the possibility of using biobased resources as feedstocks in the larger volume sectors. While biobased manufacturing will not necessarily always be cleaner, it is certain that wastes from biobased manufacturing will be more compatible with conventional wastewater treatment systems.

Pharmaceuticals

Today, many pharmaceuticals are semi-synthetic molecules, in that part of their structure is synthesised by a living organism and later modified by chemical processing. Thanks to biocatalysis optimised fermentation, and replacement of organic solvents by water, modern biotechnology contributes to cleaner production of such semi-synthetic antibiotics.

An enzymatic process for producing an antibiotic

Thermostabilised enzymes and the development of a new bioreactor process by Kaneka Corporation are used to produce 2,000 metric tons a year of amoxicillin, an antibiotic. This all-enzymatic process has displaced an older one in which part of the synthesis was carried out chemically but created problems, including coloring of the product, formation of by-products, and low energy efficiency.

Textiles and leather

The textiles industry is continuously seeking new sources of innovation, one of which is biotechnology. In 1996 the global enzyme market for textiles amounted to $ 178 million. Moreover, textile and apparel companies are spending more time and money on environmentally relevant issues. Regulatory pressure is expected to intensify for both textiles and leather as less polluting technologies become available and it becomes possible to generate less waste. 

Enzymes have been used in textile processing since the early part of this century to remove starch-based sizing, but only in the past decade has serious attention been given to using enzymes for a wide range of textile applications.

Enzymes are expected to have an even greater impact on effluent quality as more fibre preparation, pre-treatment and value-added finishing processes convert to biotreatment. In addition, enzymes are very effective catalysts even under mild conditions and do not require the high energy input often associated with chemical processes. Click here to read more about enzymes...

Food

In the food sector, biotechnology has long played an accepted role in traditional processes, such as cheese making. Both modern and traditional biotechnology can be an important supportive tool for the food industry and give considerable added value to food products. When evaluating the use of biotechnology "from the farm to the fork" it is necessary to balance the environmental impact of commercial agriculture with that of alternative production routes, such as growth of microorganisms in fermentors or from fossil fuel feed stocks. The environmental benefits of producing food additives by fermentation or enzymatic routes instead of traditional organic synthesis are similar to those for other specialty chemicals. In the case of fermentation-derived preservatives, the effect is even more favorable when the fermentation broth is incorporated in the finished product. In the most desirable situation, bacteriocin-producing cultures are used in fermented foods (such as sauerkraut) where they consume carbohydrates, naturally preserve the finished product and contribute nutritive value of their own. A biotechnology application with very great potential environmental benefit would convert waste streams from one process into raw materials for another, or upgrade underutilised raw materials into a more valuable form.

Ideas abound, including alternative uses for the grape pomace left over from wine-making, corn cobs as a substrate for citric acid production, and cranberry waste as a substrate for fungal bioinoculants. Use of the large quantities of whey produced during cheese making also hold out great promise. One successful approach has been the production of lactose-fermenting yeasts as flavoring ingredients.

Sugars from starches

Starch processing involves the conversion of maize or another grain into dextrose and other syrups by a hydrolysis reaction. This was formerly done using acid at high temperature and pressure, but dextrose yields were limited to about 80 %, the process was hazardous and expensive and produced large quantities of salt as a by-product. The initial change to enzymatic hydrolysis in the 1960s increased dextrose yields and eliminated the drawbacks of the acid process. In the 1970s, development of immobilised glucose isomerase enzymes enabled the production of high fructose corn syrup. In the 1980s, thermostable alpha-amylases helped increase yields, and in the 1990s, recombinant thermostable amylases have helped reduce costs.

Animal feed

Since the common protein sources used in animal feeds (e.g. soya, fishmeal, wheat and maize ) are deficient in methionine, lysine, threonine and tryptophan, these essential amino acids are added as supplements to monogastric diets, e.g. for poultry and pigs. Whereas methionine is produced by chemical synthesis (300,000 tons in 1996) lysine, threonine and tryptophan are produced by industrial fermentation, using mutants of Corynebacterium glutamicum and recombinant strains of E.coli.

Feed enzymes are designed to degrade components of raw materials that limit digestibility and/or lead to higher levels of excretion of manure, nitrogen and phosphorus. Endoxylanases and phytases are the best-known feed-enzyme products. Endoxylanase enzymes hydrolyse phytic acid and release inorganic phosphate, thereby avoiding the need to add inorganic phosphates to the diet and reducing phosphorus excretion. If phytase is added to feeds for pigs to liberate phosphate in the feed, phosphate release in manure is reduced by 30 %. In a country like the Netherlands, this would reduce the phosphate released into the environment by 20,000 tons a year.  The marginal price increase in the feed cost to farmers (about 2 %) would be compensated for by a reduced levy on discharge of phosphate.

Pulp and Paper

The pulp and paper industry is very capital-intensive with small profit-margins. It must meet increasing demand for pulp and paper and, at the same time, comply with increasingly stringent environmental regulations. Driven by market and environmental demands for less chlorinated products and by-products, it is the fastest growing market for industrial enzymes. In the United States, this market is projected to grow by 15 % a year for the next ten years.

In paper-making, various processes are used to separate the cellulose fibres from the lignin in wood to form a slurry (pulp) that is then processed into paper and board. Existing chemical pulping operations create a great deal of pollution. Biopulping, which involves the treatment of lignocellulosic materials with lignin-degrading fungi, has been shown to result in energy savings and strength improvements. Enzymes are now also being incorporated into the pulping process, where they offer a number of advantages.

The structure and chemical chemical composition of pulp fibres are of paramount importance for paper strength and other properties. Enzymes can be used to reduce fibre coarseness, increase paper density and smoothness, and improve appearance. Most pulp is produced using the kraft process. Kraft pulps have a characteristic brown colour, which must be removed by bleaching before manufacturing paper for writing or other products for which appearance is important. Chlorination is traditionally used, but pulp manufacturers are turning to other techniques because of consumer resistance and environmental regulations. According to studies conducted in Finaland, hemicellulases (mainly xylanases) improve bleaching. They are now being used commercially in Scandinavia, Canada, the United States, and Chile. Treating kraft pulps with xylanases significantly reduces chemical consumption with almost no loss in pulp yiels or quality. A new enzyme that is better suited to the temperatures and pH found in pulp processing has also been developed in Israel and successfully tested in a large-scale trial.

Using bacteria to remove by-products
Adding polymers to paper stops fibres from becoming waterlogged and gives the paper wet strength. However, the polymer production process creates contaminants which reduce its effectiveness. Carbury Herne Limited and Hercules Inc. have developed a bioprocess for removing these by-products.  

Two strains of bacteria are used to digest the by-products which are then washed out of the polymer before it is applied to the paper. This treatment is considered not only more environmentally acceptable, but it is also less expensive than developing a new product or a new manufacturing process to do the same job.

The process has now been adopted at production scale at two plants that make packaging paper for food liquids. As the bioreactors were built into existing production lines, costly redesign of the production process was avoided.


Energy

Biotechnology is having a major effect on the economics and the environmental impact of the energy sector. Biotechnology can produce cleaner coal and petroleum, chiefly by removing sulfur and thus reducing the environmental contaminants released during combustion. Production of low-sulfur fuels will extend fossil fuel reserves and reduce levels of air contaminants. Biotechnology also has the potential for producing equivalents to petroleum distillates, such as biodiesel. Ethanol, methane, and molecular hydrogen are even cleaner fuels, all of which would, if produced biologically, greatly lower levels of greenhouse gases.

The bioconversion of synthesis gas to liquid fuels such as methanol is also being investigated. Synthesis gas is a mixture of CO, H2 and CO2 made by the partial oxidation of any carbon-based material. Feeds for the production of synthesis gas include agricultural, municipal, and paper wastes and biomass grown specifically for this purpose. The range of feeds for synthesis gas make it a particularly versatile source of fuels. With potentially lower processing costs and greater carbon yield, fuels derived from synthesis gas are an attractive alternative to fuels produced by fermenting biomass-derived sugars.

Bioethanol

Bioethanol is a liquid transportation fuel. Currently, most bioethanol is made from sugar cane, maize and other starch crops. In the United States, close to a billion gallons of ethanol are produced annually, and in Brazil production may be four times that. However, a tax credit is needed to achieve a competitive market price. To be economically competitive with fossil fuels, the technology for producing ethanol from biomass-derived sugars will require using high-yield low-cost crops and more efficient methods of converting lignocellulosic waste material into fermentable sugars. These two areas are the focus of current research. In studies sponsored by the Department of Energy, US scientists are investigating a simultaneous saccharification and fermentation procedure for converting cellulose to ethanol. The process combines cellulose hydrolysis and fermentation steps in one vessel to produce high yields. The objective is to develop, by the year 2000, technologies for producing ethanol from biomass at a cost that will be competitive, without tax incentives, with the cost of gasoline.


Metals and minerals

There are two biotechnological processes used in the mining industry for the recovery of metals and minerals. To date, the cleanliness of bioprocesses compared to conventional metal recovery methods has not yet been established; the use of life cycle assessment would be helpful.

Biotech for mining and metals recovery includes the use of microorganisms for bioleaching and minerals bio-oxidation. These processes are employed worldwide by the mining industry to extract base and precious metals. They use bacteria, principally Thiobacillus ferrooxidans and Leptospirillum ferrooxidans and certain thermophilic (high temperature) bacteria to leach metals such as copper and gold from a sulfide mineral. Copper recovery companies that use bioleaching report that it has advantages over conventional roasters, smelters, and pressure autoclaves:
- no noxious gases are produced;
- construction time is shorter;
- environmental permits are acquired faster and environmental reporting is less onerous;
- no toxic effluents are produced;
- environmentally stable iron arsenate residue is produced;
- metal recovery is excellent;
- operation is simple and safe, as processing is at ambient temperature a nd pressure;
- smaller projects can be developed economically.

Biotechnology in the galvanising industry

Landskrona Galvanoverk in Sweden has designed a biotechnological process for metal finishing to replace the traditional alkaline degreasing process, which uses 5 % sodium hydroxide at pH 11-14. The enzymatic degreasing process has replaced the alkaline process, which creates a large volume of wastewater containing heavy metals. The new process, which is also used in two other companies, produces half as much sludge and uses a tenth the quantity of water. In addition, thanks to cost savings, the payback time is expected to be five years.

Modern biotechnology offers new approaches to cleaner industrial products and processes. At its core is the principle of working in harmony, rather than conflict, with the natural world. Biotechnological solutions can supplant technologies that pollute the biosphere and/or deplete finite resources, but industry, the research community, government, and the public need to work together to help biotechnology fulfill its potential for industrial sustainability.