Recently, a scientific speech by Yang Jun, a professor at the School of Chemistry at Beijing University of Aeronautics and Astronautics, aroused the public's attention. Originally, the scientist accidentally hung the insects and plastic hooks.
Can plastic be eaten by bugs? Does this mean that the 'white pollution' that plagues human beings has found the ultimate solution? This expectation quickly made Yang's speech a hot topic.
Occasional scientific discovery
Spring 2004, Yang Jun took out a bag of millet prepared porridge from his cupboard in his home and found that there were many holes in the plastic bags filled with rice, as well as insects and moths crawling out.
Rice is bad, can not eat, and quickly dispose of it, which is many people see the natural reaction of the scene, but this scene gave Dr. graduated from Tsinghua Environmental Engineering Environmental Biotechnology direction Yang Jun not the same inspiration Where did the insects bite, where did the plastic go? If it was eaten by insects, could the plastic be digested by insects?
Yang Jun initially speculated that plastics may be eaten by insects, but can be absorbed by insects and transformed into energy or body tissue is unknown.
'If this problem can be proved, it means the plastic can be degraded.This will be a revolutionary discovery.' 'After the Spring Festival, Yang Jun took master's student Qin Xiaoyan began to study.
Through various channels, he bought the 'moth', a waxworm, which was subsequently dissected and its contents removed and inoculated into a carbon-free media just covered with a polyethylene film.
'Carbon is the main element of life, not to Wax glucose, starch and other carbon sources, only to the film containing polyethylene, wax insects rely on the membrane to reproduce metabolism, or because there is no energy source and die.' Yang Jun told "China Science News" reporter.
By the 28th day of experiments, Yang Jun and Qin Xiaoyan observed by electron microscopy that the inclusions of the gut parasite gutted and penetrated the plastic film, meaning that the gut microbes of the waxworms degrade the plastic.
The worms survived
The intestine of the experimental waxworm gut secretes many strains, but previous studies did not refine it.
In order to learn the basic research methods, Yang Jun traveled to Oxford University in the United Kingdom for a year as a visiting scholar.After returning to China, he started a systematic and in-depth study to extract the 'pure bacteria' contained in the experiment.
Yang Jun will wax gut enteric intestine and polyethylene containing film together enrichment culture.He polyethylene as the only carbon source, 60 days enrichment culture isolated eight pure strains, and finally through the tensile Intensity test selected the two most degradative strains: Enterobacter alum and Bacillus.
Experiments have shown that these two strains indeed rely on the plastic film 'survived.' 'They grow steadily in polyethylene containing film, Long-chain CC single bond oxidative cleavage into a hydrophilic carbonyl oxygen double bond carbonyl, which is the initial mechanism of degradation. 'Yang Jun explained.
He speculated that E. coli and Bacillus could reduce polyethylene by 6% and 11%, respectively, and polyethylene by 6% and 13%, respectively, if the duration of incubation was 60 days. "This indicates Tenebrio degradation efficiency is very high.
Subsequently, Yang Jun Tenebrio Polystyrene degradation experiments. He cultivated 1500 Tenebrio, the average divided into three groups, for a period of 30 days of experiments. One group only fed polystyrene foam; the other two As a control group, the foods were their favorite wheat bran and no food, respectively, and found no significant difference in survival rates between the two groups separately fed the foam and the wheat bran.
To measure the degree of degradation of polystyrene, Yang Jun collected insect manure eaten wheat bran and foam, and GPC (gel permeation chromatography) to prove that the molecular weight of polystyrene is reduced, the heat is also reduced.
'50% of polystyrene is converted by Tenebrio molitor into carbon dioxide and its own body, can be said to be 'long muscle' as a biochemical mechanism 'gold standard', carbon 13-isotope labeled tracer experiments also confirmed this Results. 'Yang Jun said excitedly, the experiment has proved that Tenebrio can degrade polystyrene.
Plastic biodegradable new window
Yang Jun said that the plastic itself is a polymer inert material, it is difficult to be biodegradable.
'It takes about 500 years for plastics to degrade in nature and we have found a new way to efficiently degrade microbial sources by finding bacteria and enzymes that efficiently degrade plastic from the gut of insects in just 24 hours or less Will be able to degrade the plastic, which opened a window to solve the problem of petroleum-based plastic pollution. 'Yang Jun said.
Qian Yi, a member of the Chinese Academy of Engineering and a professor at Tsinghua University's Environmental School, commented that Yang's team proceeded with the natural life of insects and eating plastic and confirmed that insects and their gut microbes could efficiently degrade polyethylene and polystyrene. Is revolutionary and reveals that bacteria can take advantage of petroleum-based plastics that used to be considered as unlikely to be biodegradable, one of the biggest breakthroughs in environmental science in recent years, opening up a new door to tackling global plastic pollution.
Yang Jun told reporters that the plastic used in the experimental study are the most difficult to biodegradable petroleum-based plastics.However, you want to truly benefit mankind, but also through the industrialization of microorganisms and enzymes to be efficiently used now that he is seeking cooperation with the business , Trying to develop a new type of material with controlled degradation.