Application and prospect of modern biotechnology in environmental protection

In view of the current ecological situation in China, the application and development prospect of modern biotechnology in controlling environmental pollution and protecting ecological environment are discussed.

Modern biotechnology, ecological environment and environmental protection

1 Ecological Environment Status in China

At present, due to the pollution of "three wastes", agricultural fertilizers and farmers, as well as the pollution of waste plastics and agricultural plastic films, China's ecological environment has been seriously affected, resulting in increasingly serious water pollution and serious shortage of water resources. Half of the more than 600 cities in China are short of water, and 80 million people and 60 million livestock have difficulty drinking water. The soil pollution is serious, and the cultivated land area is sharply reduced. /kloc-since 0/0, the total amount of soil lost every year has reached 5 billion tons, and land desertification is increasing day by day. The forest coverage area is declining and the grassland is degraded, reducing the forest area by 25 million mu every year; People's health has been seriously threatened, and the incidence rate has risen sharply. Therefore, strengthening environmental protection and governance, accelerating the application of modern biotechnology and other high technologies, controlling environmental pollution, maintaining ecological balance and improving environmental quality have become the focus of environmental protection workers.

2 Modern biotechnology and environmental protection

Modern biotechnology is based on DNA molecular technology, including microbial engineering, cell engineering, enzyme engineering, genetic engineering and a series of biological high and new technologies. With the increasingly prominent environmental problems, modern biotechnology plays an important role not only in crop improvement, research and food engineering, but also in pollution control and environmental biological monitoring. Since 1980s, biotechnology, as a high-tech technology, has been attached great importance by countries and private research institutions all over the world, and has developed very rapidly. Compared with traditional methods, biological treatment methods have many advantages.

(1) Biotechnology treatment of garbage wastes is to degrade and destroy the molecular structure of pollutants. Most of the degradation products and by-products can be reused by organisms, which is helpful to minimize the environmental pollution caused by human activities, so as to achieve once and for all, leaving no long-term pollution problems, and at the same time, recycling garbage and wastes.

(2) Using fermentation engineering technology to treat pollutants, the final conversion products are mostly non-toxic and harmless stable substances, such as carbon dioxide, water, nitrogen, methane gas, etc., often in one step, avoiding repeated pollution caused by repeated transfer of pollutants. Therefore, biotechnology is a safe and thorough means to eliminate pollution.

(3) Biotechnology is a biochemical process based on enzymatic reaction, and the enzyme as a biocatalyst is an active protein, and its reaction process is carried out under normal temperature and pressure and close to neutral conditions, so most biological treatment technologies can be implemented on the spot without affecting the normal operation of other operations. Compared with chemical processes that usually require high temperature and high pressure, the reaction conditions are greatly simplified, and it has the advantages of simple equipment, low cost, good effect, stable process and simple operation.

Therefore, biotechnology has been widely used in environmental monitoring, industrial cleaner production, the treatment of industrial waste and municipal solid waste, and the harmless treatment of toxic and harmful substances.

3 Application of modern biotechnology in environmental protection

3. 1 Biological purification of sewage

The composition of toxic substances in sewage is very complicated, including various phenols, cyanide, heavy metals, organophosphorus, organic mercury, organic acids, aldehydes, alcohols and protein. Microorganisms can remove the toxicity of sewage through their own life activities, thus transforming toxic substances in sewage into beneficial non-toxic substances and purifying sewage. Using immobilized enzyme and immobilized cell technology to treat sewage is one of the methods of biological purification of sewage at present. Immobilized enzyme and immobilized cell technology are enzyme engineering technologies. Immobilized enzyme, also known as water-insoluble enzyme, is a derivative that combines water-soluble enzyme with solid insoluble carrier through adsorption or chemical bond, making the enzyme insoluble in water but still retaining catalytic activity. Microbial cells are natural immobilized enzyme reactors, which can directly immobilize microbial cells by preparing immobilized enzymes, that is, immobilized cells that can catalyze a series of biochemical reactions. Organic pollutants and inorganic metal poisons in wastewater can be efficiently treated by immobilized enzymes and immobilized cells, and there have been many successful examples at home and abroad. For example, in Germany, enzymes that can degrade 9 pesticides such as parathion were immobilized on porous glass and silicon beads to make enzyme columns, which were used to treat parathion wastewater, with a removal rate of more than 95%; In recent years, great progress has been made in the application of immobilized cell technology in the degradation of surfactant linear alkylbenzene sulfonate (LAS) in synthetic detergents. For the wastewater containing 100mg/L, the degradation rate and enzyme activity retention rate are above 90%. The degradation of phenol-containing wastewater by immobilized yeast cells has also been actually applied to wastewater treatment.

3.2 Bioremediation of Contaminated Soil

Heavy metal pollution is the main pollutant that causes soil pollution. Bioremediation of heavy metal pollution is to reduce and purify heavy metals in soil or reduce their toxicity by using the functions of organisms (mainly microorganisms and plants). Its principle is to change the chemical form of heavy metals in soil through biological action (such as enzymatic reaction), so as to fix or detoxify heavy metals, reduce their mobility and bioavailability in soil environment, and realize the reduction, purification and fixation of heavy metals through biological absorption and metabolism. The bioremediation process of polluted soil can increase the content of soil organic matter and stimulate the activity of microorganisms, thus improving the ecological structure of soil, helping soil fixation, inhibiting wind erosion and water erosion and preventing soil erosion.

3.3 Eliminate white pollution

Waste plastics and agricultural plastic film have existed for a long time, which is estimated to be an important part of environmental pollution. It is estimated that there are about one million tons of plastic waste in soil, ditches and rivers in China. The residue of plastic in soil will lead to the reduction of crop yield. If we don't take measures to continue to use it, there will be no food for many cultivated land in more than ten years. It can be seen that a large amount of plastic waste seriously affects the ecology and environment, and it is urgent to study and develop biodegradable plastics. Using bioengineering technology, on the one hand, dominant microorganisms that can degrade plastics and agricultural films can be widely separated and screened, and high-efficiency degrading bacteria can be constructed; On the other hand, we can isolate and clone degradation genes and introduce them into some soil microorganisms (such as rhizobia), so that they can play their respective roles at the same time and degrade plastics and agricultural films quickly. At the same time, we should vigorously promote the research, development, production and application of degradable plastics and mulching films.

Some microorganisms can produce polymer compounds similar to plastics, that is, polyester, which is an endogenous storage substance of microorganisms and can be produced by fermentation. Because of its biodegradability, high melting point, high elasticity and non-toxic substances, the resulting plastics and mulching films have excellent application prospects in many fields. In order to reduce costs and increase production, people are using recombinant DNA technology to transform related microorganisms. At present, the production of poly (β-hydroxyalkanoic acid) by microbial fermentation is a research hotspot in this field. Researchers are trying to construct an autolytic PHAs-producing strain, namely, fermentation PHAs recombinant strain. After accumulating a large amount of PHAs, signal substances are added to produce cleaved proteins, destroy cell walls and precipitate PHAs, thus simplifying the extraction process of intracellular products.

3.4 Eliminate chemical pesticide pollution

Generally speaking, about 80% of the chemical pesticides used will remain in the soil, especially chlorinated hydrocarbon pesticides, which are the most difficult to decompose and cause residues and toxicity through the ecosystem. Therefore, people have been looking for safer and more effective methods for many years, and using microorganisms to degrade pesticides has become an important aspect of eliminating pesticide pollution to the environment. Some microorganisms that can degrade pesticides gradually decompose pesticides into final products CO2 and H2O through mineralization, which is thorough and generally does not bring side effects. Some of them transform pesticides into metabolizable intermediates through * * * metabolism, thus eliminating residual pesticides from the environment. The degradation result of this method is complex, which has both positive and negative effects. In order to avoid negative effects, it is necessary to transform microorganisms known to degrade pesticides through genetic engineering and change their biochemical reaction pathways to obtain the best degradation and detoxification effect. In order to completely eliminate the pollution of chemical pesticides, it is best to fully popularize biological pesticides.

The so-called biological pesticides refer to a large class of substances produced by organisms with the function of preventing and killing pests and weeds, mostly biological metabolites, mainly including microbial pesticides, agricultural antibiotic preparations and microbial herbicides. Among them, microbial insecticides have been widely studied, including viral insecticides, bacterial insecticides, fungal insecticides and actinomycetes insecticides. It has not been widely used for a long time. At present, people are using recombinant DNA technology to overcome its shortcomings and improve the insecticidal effect. For example, one of the research hotspots of virus insecticides is the transformation of baculovirus genetic engineering, and people are studying the cloning of exogenous toxic protein genes such as neurotoxin genes into baculovirus to enhance the toxicity of baculovirus. Genes that can interfere with the normal life cycle of pests, such as the gene encoding juvenile hormone esterase, are inserted into the genome of baculovirus to form recombinant baculovirus, so that it can express related hormones, thus disrupting the hormone balance of pests, interfering with their normal metabolism and development, and achieving the purpose of killing pests.

refer to

1 Kong Fanxiang. Environmental biology [M]. Beijing: Higher Publishing House, 2000.

2 Chen Jian. Environmental Biotechnology [J], Progress in Bioengineering, 200 1(5)

3 Jiang, people. Exploitation and utilization of microbial resources [M]. Beijing: China Light Industry Press, 200 1.