China Educational Equipment Purchasing Network: The toxicity of various mercury compounds varies greatly. Elemental mercury is basically non-toxic; the ascending mercury in inorganic mercury is highly toxic; phenylmercury in organic mercury decomposes quickly and is not toxic; methylmercury is easily absorbed into the human body, is not easily degraded, and is excreted very slowly, especially It is easy to accumulate in the brain and is the most toxic. It can be seen that the damage of mercury to our health is great. Scientists are expected to use bioengineering technology to "modify" a bacterium into a pro-mercury characteristic, hoping to use this genetically modified bacterium to help eliminate mercury pollution in the environment.

Industrial emissions, gold mining and other human activities are extremely susceptible to mercury pollution of water and soil environment. Through the food chain, mercury pollution in specific areas threatens human health, and the existing methods for removing environmental mercury pollution are extremely costly.

A bioengineering research team at the University of Puerto Rico in the United States injected two "pro-mercury" genes into an Escherichia coli. After the two genes were transferred into Escherichia coli, they produced a protein called metallothionein and a biological enzyme called polyphosphate kinase.

Metallothionein and polyphosphate kinase can effectively fix metal substances that enter E. coli to prevent cell poisoning.

Then, the researchers put two kinds of transgenic Escherichia coli into a nutrient solution containing high-dose mercury, and found that the transgenic E. coli that produced polyphosphate kinase was 16 times more resistant to mercury than ordinary E. coli, and produced metal This rate of transgenic E. coli of thioprotein is as high as 24 times.

After living in the nutrient solution for 5 days, the two transgenic E. coli "swallowed" about 80% of the mercury in the environment.

It was reported on August 16 that this genetically modified E. coli is expected to become a new tool for eliminating environmental mercury. Although the team has not yet assessed the cost of actual use, it should be significantly lower than the cost of existing environmental mercury pollution removal technologies from US $ 100,000 to US $ 150,000 per kilogram.

Foreign Journal Guide

Sources of mercury pollution:

Human activities cause mercury pollution in water, mainly from wastewater discharged from industries such as chlor-alkali, plastics, batteries, and electronics. It is estimated that from 1970 to 1979, the total amount of mercury directly discharged into water bodies by human activities was about 16,000 tons; the total amount of mercury discharged into the atmosphere was about 100,000 tons; What is discharged into the atmosphere and soil will also return to the water body along with the water cycle.

Since mercury is distributed in the atmosphere, soil and water bodies under natural background conditions, the migration and transformation of mercury also occurs between land, water and air. The gaseous and particulate mercury in the atmosphere drifts with the wind, and part of it falls to the ground or water body by wet or dry sedimentation. The mercury in the soil can volatilize into the atmosphere, can also be washed by precipitation into surface water and penetrate into groundwater. Part of the mercury in surface water enters the atmosphere due to volatilization, and most of it settles into the sediment. No matter what form it takes, the mercury in the sediment will be directly or indirectly converted into methylmercury or dimethylmercury under the action of microorganisms. Dimethylmercury can be decomposed into methylmercury under acidic conditions. Methylmercury is soluble in water, so it returns from the sludge to the water. Methylmercury ingested by aquatic organisms can accumulate in the body and continue to enrich through the food chain. The concentration of methylmercury in fish polluted by mercury can be ten thousand times higher than that in water, endangering fish and harming the human body through the food chain.

Although mercury is a cumulative poison, the human body has a certain ability to excrete mercury. Tests show that adults taking 0.025 mg of methylmercury per day will not accumulate in the body due to the body's excretory capacity. If the intake exceeds the body's excretion capacity, it will accumulate in the body. Minamata disease in Japan is caused by the accumulation of methylmercury in the brain and damage to brain tissue. Metal mercury in other tissues of the body may be oxidized into an ionic state and transferred to the kidneys to accumulate. The clinical manifestations of chronic mercury poisoning in the human body are mainly neurological symptoms, such as headache, dizziness, numbness and pain in the limbs, muscle tremors, and movement disorders. Acute mercury poisoning will occur when a large amount of mercury vapor is inhaled. Its symptoms are hepatitis, nephritis, proteinuria and uremia. These diseases have serious sequelae and high mortality, and can also be passed on to the baby through the mother. Some fishermen in China's Songhua River and Jihe River Basin have obvious accumulation of mercury, and there have been patients with "quasi-Minamata disease".

Due to the high toxicity of mercury, the dose of poisoning is small. Therefore, China's drinking water and farmland irrigation require mercury content not to exceed 0.001 mg / L, and fishery water requires mercury to not exceed 0.005 mg / L.

Baking Tools

Cake Decorating Tools,Baking Tools,Baking Utensils,Cake Baking Utensils

Yangjiang Yado Kitchen Industry Co., Ltd. , https://www.yadokitchen.com