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Concernant la présentation orale.

La durée est parfaite (5:04 mins)

Attention Ă  la prononciation de certains mots comme "beliefs", "starch", "lower", "sugar", "carry out", "about", et certains mots "transparents" comme "central", "crucial", "digest", "question",…

Il y a des mots mal prononcĂ©s dans certaines phrases comme par exemple celle-ci : ""the Earth was has never been so weakened by her bad habits, plastic ??? waste creation of humanity", ou "We wondered how well the use of organ plastic bags???? environmental pollution" ou encore celles-ci : "For protocol N°1 we have obtained take colour film that will be useful in the other protocol was a manufacture bag . For protocol N°2 the goal is to see is there a ??? between the resistance…"

N'oublie pas de bien prononcer le morphème –ed : "estimated"

Il faut bien prononcer les "s" Ă  la 3ème personne du singulier et après chaque mot au pluriel, exemple "breaks, "it degrades, it decomposes,…

C'est bien présenté et ton texte est bien écrit.

E.T.L.V - P.T.A Bioplastic :

I/ The origin of plastic:
Since 1950, global plastic production has increased. Reached a record 320 million tonnes in 2015, or 10.1 tonnes per second, consuming 8% of world oil production. The consequences of this plastic accumulation are enormous. Plastic bags can block waterways and make natural disasters worse. Plastic bags can increase the spread of disease. The accumulation of plastic is even more worrying today, because most plastics are not biodegradable, they will slowly break down into smaller pieces called micro plastics. Several studies have shown that the decomposition of plastic bags and polystyrene containers takes thousands of years, during which the soil and water are contaminated. To make plastics, we use a lot of petroleum, which is a non-renewable resource. Currently, it is estimated that 6% of the oil used in the world is used to make plastics. By 2050, this number is predicted to increase to 20%. It is a good reflection of the increase in plastic consumption. When you know that the first use of plastic is short-lived packaging, how useless it is. In addition, contrary to popular belief, plastics are rarely recycled, the alternative is bioplastics. Because bioplastics are made up of plant cells. It can also be made from vegetable starch, cereals such as wheat, corn or potatoes, starch glucose or vegetable oil.

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siencesetavenir.fr and tpe-lasource-leplastique.e-monsite.com

II/ The problem :
Plastic can be harmful to health because when you eat food that has been kept in plastic or when a child chews on an object. These are situations where compounds can migrate from plastic to the body and we then find ourselves exposed to potentially carcinogenic substances, endocrine disruptors … Of course, plastics are not ecological. Worryingly, it is ubiquitous and often used for single-use items, which generates a lot of waste, but is still poorly managed. Since the 1960s, the production of plastics has multiplied by 20, which is not surprising, we use plastics everywhere: packaging, kitchen utensils, various containers, dashboards, electrical and electronic equipment, decoration, furniture. . , Toys. Packaging represents 40% of the annual use of plastics in Europe. Among the plastic waste found in the ocean, 47% are single-use plastic objects. Rising oil prices in recent years have increased resource limits and the desire for better climate protection and sustainability. Plastics everywhere play a central role in our daily lives, and that seems crucial. However, it represents a real danger for our planet, in particular because of its slow degradation. Even now that recycling is the way to limit the damage, there is still time to reduce daily plastic waste at home. The earth has never been so weakened by our bad habits. Plastics are among the worst creations of humanity. At first it seemed harmless. These practical plastics have gradually entered our lives and are found in our homes, gardens, supermarkets, offices, schools, dishes, clothes, tools and even food … The oceans are becoming a real open trash can. Due to its durability, plastic is dangerous for animals living in our vast oceans and even on land! The turtle takes the plastic bags, which people throw into the sea, jellyfish eventually suffocate. We all know that no animal can digest plastic, and these animals will eventually die … But we also end up becoming victims of plastic. Therefore, we are faced with a number of problems which reflect many assumptions and involve the problems we have studied: "How will the use of organic plastic bags limit environmental pollution?" In order to really reduce the consumption of plastic, we will turn to bioplastics.


III/ The protocols used to solve our problem:
To solve this problem, we carried out eight manipulations. First, we made a bioplastic film based on corn starch. Then, we compared the resistance of the different bags (bioplastic bags, plastic bags and, manufactured bags). The goal is to see if there is a link between the resistance of the plastic and its moment of degradation. Then we composted. The goal is to understand how the different plastic bags degrade naturally. Then, enzymology, consists in identifying bags which degrade in a short time, and microbiological tests to prove the characteristics and the concentration of Bacillus subtilis Finally, we conducted a small experiment on Fehling's liquor to discover reducing sugars. The aim of our various manipulations is to prove that organic plastic bags are the least polluting. In order to be able to solve our problems, we will present the different protocols as a whole in the first part. The second part specifically presents one of the different manipulations carried out to answer our questions: it is a microbiological test which aims to discover the different characteristics of the bacterium Bacillus subtilis. In this perspective, eight protocols have been developed to compare bioplastic bags with plastic and also manufactured bags. The results of these experiments are described in the third part. Finally, we will finish with the conclusion by answering the problem.

IV/ Microbiological tests of Bacillus subtilis bacteria:
This protocol allows us to determine the different characteristics of the bacterium Bacillus subtilis, for which we carried out different manipulations: first, we seeded the bacteria in different culture media, such as Hugh and Lefson, VF agar, GTS and starch agar using a bacterial suspension. We took an öse from the slant agar containing Bacillus subtilis and seeded it in a hemolysis tube containing 1 ml of distilled water. These microbiological experiments will allow us to understand the culture method, the attack path, and its aspect of the Bacillus subtilis bacteria, in particular to observe whether it degrades starch. Because starch is the raw material for biodegradable plastic bags. This protocol will allow us to answer certain questions, for example if Bacillus subtilis will hydrolyze starch? Will Bacillus subtilis bacteria facilitate the degradation of biodegradable plastic bags? Because bacteria that produce amylase can hydrolyze starch:
Starch -—> maltose + glucose

V/ The results obtained:

-Hugh and Leifson: Determines the pathway of glucose as an energy source for most bacteria, it is studied thanks to the presence of glucose as the only carbohydrate but also bromothymol blue as a pH indicator. We could observe in the test tube that its color has changed, the bottom of the test tube is green and the top of the test tube is yellow. We can say that glucose is attacked in the presence of oxygen, so it is an oxidative pathway.

-VF Agar: used to determine the respiratory type of a bacteria. We observe a culture on the surface of the VF tube, there is the presence of oxygen. So it's a strict aerobic.

-GTS Agar: It is a basic medium which can cultivate non demanding bacteria of the strain. We were able to observe a large colony with an irregular and flat outline, an opaque consistency and a yellow pigmentation, so it is a pure strain.

- Starch agar: allows the study of the hydrolysis of starch by amylase. After incubation, the diiod contained in Lugol is added to the starch agar, this makes it possible to highlight around the colonies, which can prove the presence of starch. We can see a clear halo around culture. Starch degrades and bacteria have amylase, which is the enzyme. To conclude it is more starch. Diode formula: C6H10O5 + I2 = C6H10O4I + IO

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VI/ Results obtained from all protocols:

- Protocol n°1:We have obtained a thick and colored film which can be used for our different protocols and form manufactured plastic bags.

- Protocol n°2: We have noticed that the plastic bags and the plastic bags produced have the same resistance. However, the resistance of biodegradable plastic bags to lower resistance than that of plastic bags and manufactured plastic bags. Therefore, we can conclude that this has nothing to do with degradation, because the fastest degradable plastic, that is to say the most ecological plastic is the favored one. The plastic bag with the longest degradation time is the most harmful to the environment.

- Protocol n°3: For the composts inside there was no drying out of the compost. The plastic bags made with or without Bacillus subtilis bacteria started to destroy themselves, that is to say that the plastic made became small pieces, then for the biodegradable bags with Bacillus subtilis, it did not change. Without bacteria, the plastic folds back. For ordinary plastic bags, neither the interior nor the exterior will change. Then, plastic made outside with or without bacteria breaks down. But there are still small pieces, and ultimately, no matter where they are, the biodegradable plastic will not change. We can conclude that for ordinary plastic bags, it takes longer to degrade. Next is the biodegradable plastic bag, which also takes longer, but less than regular plastic. To finish the plastic bag made, it only takes a few days to degrade completely, so it is the one with the least degradation time.

- Protocol n°4: For the soil Protocol, we encountered difficulties, firstly because we took test tubes as support. They prevent us from seeing the soil and the piece of plastic correctly. Then we optimized for Petri dishes as a support. This allows us to observe not only the soil, but also the piece of plastic correctly. Unfortunately, however, due to the incubation temperature, the soil has dried out. We can get roughly correct results. This is why we observed that the soil became very dry, in the presence or in the absence of Bacillus subtilis, with the piece of plastic bag, biodegradable and manufactured. Then the autoclave soil containing the plastic bag is placed on top of the mold without the bacteria and becomes dry with the bacteria. The autoclave soil with the biodegradable bag becomes mud in the presence of the bacteria and becomes dry without the bacteria. The autoclave soil with the biodegradable bag and the manufactured bag dries out with or without bacteria. To conclude knowing that plastic bags are the most harmful to the environment, we observed two different types of soil. We can conclude that the autoclave earth reacts the most to plastic.

- Protocol n°5: The higher the concentration, the more severe the degradation of the plastic. In this case, Bacillus subtilis (containing alpha amylase) is more effective than alpha amylase vis-Ă -vis plastic. The non-degradable plastic bag with a concentration of 0,000 mg / mL, so we can say that it will not degrade even after 50 minutes. It can also be observed that in both cases, the bags produced are of high concentration in a short time. We can conclude that the most degradable bag is the manufactured bag.

- Protocol n°6: In general, Bacillus subtilis is a pure strain which degrades glucose, that is to say that there is attack of glucose only in the presence of dioxygen so it is an oxidative pathway. We only observe the culture in the presence of O2, so its breathing type is strictly aerobic. Finally, we obtained a starch + , because after the addition of Lugol, clear spots around the culture medium were observed, which indicates that the starch has been hydrolyzed.

- Protocol n°7: We calculated the mass concentration of the Bacillus subtilis bacteria and obtained 1.2 UFC / ml.

- Protocol n°8: For the Fehling protocol, we first obtained a blue test tube, that is to say that there is no reducing sugar. It can be concluded that the test solution does not contain reducing sugar. Second, we used distilled water and 8 drops of glucose in a test tube. We obtained a red precipitate, that is to say the presence of reducing sugar. (After a long period of experimentation, where we have seen the results. It will take longer to see the total degradation of the plastic bags produced).


VII/ Conclusion:
Taking into account all the results of the various experiments carried out, we can answer the following question: "How will the use of bioplastic bags limit environmental pollution?". The plastic bag that can reduce pollution the most is the plastic bag made because it degrades the most quickly. This is proven in the composting system, because the bag breaks down into pieces and changes color. Once used, if placed in the wild, in contact with the ground, it will degrade for about two months. Compared to normal plastic bags, it will degrade for at least 400 years. But we also know that not everyone can make their own homemade plastic bags, because some people have no materials or means. We have a second solution, which is to use biodegradable plastic bags to limit environmental pollution, because we have proven that its destruction rate is slower than the plastic bags produced, but faster than ordinary plastic. . Also in contact with a high heat source, it will deform and begin to self-destruct. Therefore, bioplastic bags will limit pollution because the second plastic bag requires a minimum of time to degrade, which will limit pollution of the environment.

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idealo.fr and geo.fr
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