Another major episode in the emergence of biotechnology was the production of penicillin from the mould Penicillium, initially on a very small scale, by Howard Florey and colleagues in Oxford during World War II. The process was soon scaled up, and other microbes were harnessed to manufacture a wide range of antibiotics (such as streptomycin for the treatment of tuberculosis). Today, biotechnology is facing a major challenge in developing new antibiotics to supplant those to which disease-causing bacteria have become resistant. One current development is the genetic engineering of micro-organisms to synthesize “hybrid antibiotics”, whose molecules differ from those produced naturally.
Biotechnologists now “program” bacteria to make many other types of drugs that the organisms could not otherwise produce. Human insulin, for the treatment of diabetes, is manufactured by bacteria into which genetic engineers have introduced the gene coding for that particular hormone. Unlike the types of insulin obtained from pigs and cows, it is identical with insulin secreted by the human pancreas. Human growth hormone (used to treat children who would otherwise reach abnormally short stature) is also made by bacteria carrying the relevant human gene. It is free of the risk of contamination with microbes such as the prion that causes Creutzfeldt-Jakob disease, which was a danger when the hormone was obtained from human corpses. Other pharmaceuticals manufactured by genetically engineered micro-organisms include interferons for the treatment of hepatitis B and certain cancers, and erythropoietin, which is given to kidney-machine patients to help them replenish the red blood cells that they lose during dialysis.
Preventing Infectious Diseases
Biotechnology is beginning to revolutionize vaccine production. Formerly limited to weakened or killed versions of the microbes that cause disease (such as the two alternative types of polio vaccine), researchers can now turn totally harmless microbes into vaccines. This means introducing genes, taken from disease-causing micro-organisms, that determine the production of particular antigens, which in turn, induce the recipient to make protective antibodies. The technique facilitates immunization against diseases for which fully satisfactory vaccines have not existed hitherto. It also opens up the possibility of engineering vaccines conferring protection against several infections simultaneously. A genetically engineered vaccine is already widely used against the liver infection hepatitis B. Another is helping to reduce the incidence of rabies in foxes in Europe.
Environmental Applications
A rapidly developing area of biotechnology is “bioremediation”, the use of microbes to break down pollutants in the environment, particularly the soil. One approach is based on the fact that contaminated land (such as the derelict site of a former gas works) often contains micro-organisms capable of attacking chemicals that would be toxic to many other types of living cell. Their growth can sometimes be massively increased by introducing nutrients or air into the soil. The population of scavengers then breaks down the pollutants. Another technique is to introduce microbes specifically chosen for their detoxifying capacity. A third approach is to remove the contaminated soil, expose it to scavenging microbes under controlled conditions, and return it to the site afterwards.
Bacteria are used in many countries to leach metals such as iron, zinc, and uranium out of inaccessible and low-grade ores. A tenth of the copper produced annually in the United States is recovered in this way. “Microbial mining” is increasing in importance as high-grade and easily accessible mineral deposits are depleted.
Programming Plants
Plant biotechnology has the same goal as traditional plant breeding: to develop crops and other plants with advantages such as resistance to pests and drought, and improved palatability and nutrient content. However, more precise and predictable results can now be achieved by modern techniques that allow individual genes to be transferred, in contrast to the large numbers of genes introduced when one plant is crossed with another by conventional methods.
A typical recent development was the development of maize that was resistant to the European corn borer—a pest that destroys 7 per cent of the world's annual maize crop. The inbuilt resistance was achieved by incorporating into the plant a gene normally carried by the soil bacterium Bacillus thuringiensis, which “instructs” the maize to produce a chemical toxic to many pests. Hitherto, farmers have controlled the corn borer by spraying plants with either the bacterium or synthetic chemicals. However, this has been an imperfect solution because there are only a few days in the corn borer's life when spraying is effective.
Biotechnology has also yielded plants resistant to certain viruses, fungi, and roundworms, as well as varieties insensitive to the herbicides that farmers use to control weeds. Quality characteristics can be improved too—for example, by increasing the levels of certain proteins that determine the suitability of wheats for making bread. Most recently, oilseed rape has been altered genetically to produce chemicals of potential industrial importance. Other plants could be used in the future to make vaccines more cheaply than by growing cultures of microbes.
Animal Biotechnology
Ease of production is the motive behind the current emergence of biotechnology using animals. Just as microbes and plants can be altered genetically, so new genes may be introduced into fertilized embryos. Thus the human gene for alpha-1 antitrypsin, which is used to treat the chronic lung condition emphysema, has been incorporated into the DNA of sheep in such a way that it programmes the animals to produce the alpha-1 antitrypsin in their milk. The same method has been adopted to direct sheep to produce blood-clotting factor IX, which is required by people suffering from haemophilia. Other new genes have been introduced to boost disease resistance in sheep and pigs, and to improve sheep's wool and increase its rate of growth.
Animal biotechnology has attracted criticism from animal welfare groups, which point out that some experiments have had adverse effects on the animals. However, scientists defending this type of work say that it is essential, from both ethical and safety standpoints, that the animals enjoy good health (indeed better health than most animals in the wild) and have a normal lifespan.
Critiques of Biotechnology
Lobby groups in certain countries (especially in Germany) have opposed other aspects of biotechnology. One concern is the alleged unpredictability of releasing genetically altered organisms into the environment and the possibility that the new genes they carry may cause harm if they subsequently get into other living organisms. It can be argued, however, that the far greater precision of genetic engineering, as compared with gene transfers in nature, reduces rather than increases such dangers. In addition, the official committees that regulate biotechnology in most countries assess these risks very carefully before giving permission for particular experiments to proceed.
Other anxieties centre on the impact of modern biotechnology in poorer countries. While its supporters emphasize benefits such as improved crop varieties and more effective vaccines, its opponents point to potentially adverse economic effects. In addition to consequences for peasant farmers, who could become heavily reliant on particular crop varieties supplied by multinational companies, there could be adverse macroeconomic repercussions. For example, the transfer into bacteria of a gene responsible for a highly desirable trait of an important cash crop (such as the taste of vanilla) might lead to that product being made cheaply in developed countries, with serious effects on existing producers.
