Plastic industry has become of vital importance for the comfort and quality of our lives, due to numerous qualities as strength, lightness, low cost and durability. Their downside is the negative impact over the environment, due to the accumulating of millions of tons per year. Therefore, the development of biodegradable plastics seems a key issue for further development.
PHAs are hydroxyalkanoate polyesters that are used as energy storage for bacteria. Polyhydroxybutyrate(PHB) is a biodegradable polymer, with similar properties to polypropylene, which gives it great potential as alternative source of plastics. PHB is linear polyester of D-3-hydroxybutyric acid, with high molecular weight, accumulated as a storage carbon in different microorganisms. The PHB-producing bacteria require an environment rich in sucrose, glucose or ethanol, all expensive raw materials. Efforts have been made in the past years to overcome those disadvantages, by producing PHB from plants. (Gehrke, 2009)
The first attempts to establish fermentative production of PHA happened 40 years ago, using stains of Ralstonia eutropha and Alcaligenes latus.
Biopol®, a polymer developed by ICI (Imperial Chemical Industries) was produced using a mutant stain Ralstonia eutropha using glucose as a carbon source. That was the start of the commercially available PHVBs, in the 1980s. After the change of proprietorship to Monsanto, the bioplastic’s division was sold and the patent was bought by a Cambridge, (MA, U.S.A.) company called Metabolix (source: press release 16 May 2001, Metabolix.com).
The research continued, adding new naturally PHA- producing bacteria to the list, whilst other microorganisms were modified to do so. The carbon source usually used was gluc...
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...ndia : University of Pune.
9. Mousavioun, P. (2011). Properties of Ligning and Polyhydroxybutyrate Blends. Queensland, Australia: Queensland University of Technology.
10. Nisha V. Ramadas, S. K. (2009). Polyhydroxybutyrate Production using Agro-industrial Residue as Substrate by Bacillus sphaericus NCIM 5149. Kerala: National Institute for Interdisciplinary Science and Technology.
11. Peter H. Yu, H. C.-L.-H.-P. (1999). Conversion of industrial wastes by Alcaligenes Latus into Polyhydroxyalkanoates,.
12. Product information . (fără an). Preluat de pe mirel plastics: http://www.mirelplastics.com/discover/default.aspx?ID=1783
13. Udpuay, S. C. (2008). Production and Characterization of Polyhydroxybutyrate from Molasses and Corn Steep Liquor produced by Bacillus megaterium ATCC 6748 . Phitsanulok ,Thailand: Dept. of Biology, Fac. of Science, Naresuan University, .
Table 6 shows the results of the biochemical tests. The isolate can obtain its energy by means of aerobic respiration but not fermentation. In the Oxidation-Fermentation test, a yellow color change was produced only under both aerobic conditions, indicating that the EI can oxidize glucose to produce acidic products. In addition to glucose, the EI can also utilize lactose and sucrose, and this deduction is based on the fact that the color of the test medium broth changed to yellow in all three Phenol Red Broth tests. These results are further supported by the results of the Triple Sugar Iron Agar test. Although the EI does perform fermentation of these three carbohydrates, it appears that this bacterium cannot perform mixed acid fermentation nor 2,3-butanediol fermentation due to the lack of color change in Methyl Red and Vogues-Proskauer
Casullo De Ara 'Ujo, H. W., Fukushima, K. and Takaki, G. M. C. 2010. Prodigiosin production by Serratia marcescens UCP 1549 using renewable-resources as a low cost substrate. Molecules, 15 (10), p. 6931-6940.
BPA pollution into aquatic environments occurs through two main routes: (1) direct dumping of BPA-containing plastics, and (2) efflue...
The most common form of polyethylene is petroleum based or olefins based; as before mentioned polyethylene compounds have a wide commercial applicability and are made from non-renewable resources (Harding, Dennis, von Blottnitz, Harrison, & S.T.L., 2007). Its manufacturing processes are regarded as energy intensive and release significant amount of CO2 and heat into the atmosphere (Broderick, 2008). Next a little more detailed description of polyethylene’s production processes will be presented, with a focus on the way the material inputs are extracted and synthesized.
Every year, an estimated 8 million tons of plastic waste enters our environment, severely polluting oceans, beaches, forests, and even the towns and cities we live in. In the ocean alone, it is believed that 5.25 trillion pieces of plastic pollutes the waters (“Plastic Statistics”, Ocean Crusaders).The majority of plastic pollution can be traced back to single-use items, such as grocery bags, bottles, and plastic packaging. According to United Nations Environment, “At the rate we are dumping items such as plastic bottles, bags and cups after a single use, by 2050 oceans will carry more plastic than fish…” (“UN Declares War on Ocean Plastic”, UN Environment). This pollution is a major problem and endangers not only the environment, but human
Biomass Packaging Co., et al. Plastic in the ocean does not biodegrade, it only breaks down into smaller, and smaller pieces, some pieces are so small they cannot be seen by the naked eye.... ... middle of paper ... ... 11 April 2014.
Bacterial cells, like plant cells, are surrounded by a cell wall. However, bacterial cell walls are made up of polysaccharide chains linked to amino acids, while plant cell walls are made up of cellulose, which contains no amino acids. Many bacteria secrete a slimy capsule around the outside of the cell wall. The capsule provides additional protection for the cell. Many of the bacteria that cause diseases in animals are surrounded by a capsule. The capsule prevents the white blood cells and antibodies from destroying the invading bacterium. Inside the capsule and the cell wall is the cell membrane. In aerobic bacteria, the reactions of cellular respiration take place on fingerlike infoldings of the cell membrane. Ribosomes are scattered throughout the cytoplasm, and the DNA is generally found in the center of the cell. Many bacilli and spirilla have flagella, which are used for locomotion in water. A few types of bacteria that lack flagella move by gliding on a surface. However, the mechanism of this gliding motion is unknown. Most bacteria are aerobic, they require free oxygen to carry on cellular respiration. Some bacteria, called facultatibe anaerobes can live in either the presence or absence of free oxygen. They obtain energy either by aerobic respiration when oxygen is present or by fermentation when oxygen is absent. Still other bacteria cannot live in the presence of oxygen. These are called obligate anaerobes. Such bacteria obtain energy only fermentation. Through fermentation, different groups of bacteria produce a wide variety of organic compounds. Besides ethyl alcohol and lactic acid, bacterial fermentation can produce acetic acid, acetone, butyl alcohol, glycol, butyric acid, propionic acid, and methane, the main component of natural gas. Most bacteria are heterotrophic bacteria are either saprophytes or parasites. Saprophytes feed on the remains of dead plants and animals, and ordinarily do not cause disease. They release digestive enzymes onto the organic matter. The enzymes breakdown the large food molecules into smaller molecules, which are absorbed by the bacterial cells. Parasites live on or in living organisms, and may cause disease. A few types of bacteria are Autotrophic, they can synthesize the organic nutrients they require from inorganic substances. Autotrophic bacteria are either photosynthetic or Chemosynthetic. The photosynthetic bacteria contain chlorophyll that are different from the plant chlorophyll. In bacterial photosynthesis, hydrogen is obtained by the splitting of compounds other than water.
Tillman, Gerngoss U., and Slater C. Steven. "Making Packaging Greener – Biodegradable Plastics." Biodegradable Plastic News. 2 Aug. 2007 <"Background Press Information." Background Press Information. 28 July 2007 .>.
The world population is living, working, and vacationing along the coasts. They are contributing to an unprecedented tide of plastic waste. Pollution is defined as the process that alters a substance or molecule on planet earth, the pollution is caused by the physical contact of an organic decaying particle with a clean particle in the same spot, at the time the two particles join together is when occurs pollution in which the environment is greatly altered. Too many, plastic is a modern day miracle, versatile, inexpensive and durable (Rochman 2014). To others, it is a scourge, a non-degradable pollutant that threatens to choke the global environment. Plastic pollution has led to the deaths of many animals, natural resources, and people (Rochman 2014). It is time to change America’s thinking and to learn from past mistakes.
Although companies across the globe continue to produce multiple polycarbonate #7 plastic products with BPA, more is being noticed about the adverse health effects to humans can be harmful. Testing on mice has proven that some exposure to BPA can be linked to Cancer and neurological disorders. In countries which have banned the use of BPA in different products, would agree that this chemical is toxic and dangerous. However, as long countries like the United States, who do not currently support banning BPA countrywide due to limited scientific data to back all claims, BPA will continue to be a global issue which continues to be hidden in the dark and a mystery globally
Culture plates of yeasts strains: S41, a pet 1 and M240, conical flasks containing Yeast Extract Potassium Acetate (YEPA), Yeast Extract Peptone Dextrose (YEPD) and Yeast Extract Palm Olein (YEPPO) media, pH indicator, inoculation loop, microscope, methylene blue, Bunsen burner and incubator.
Millions of plastic bags are given out to consumers by supermarkets and stores to carry their goods in. They are also cheap, light, durable, easy to carry and in many cases, free. The most commonly used shopping bag is made of High Density Polyethylene (HDPE). This type is used in the majority of supermarkets and stores. After these bags are used, they often end up in landfills or as litter, roughly only three percent of plastic bags is actually recycled per year (Planet Ark, 2011). The materials used in making plastic bags make them non-biodegradable. According to the science dictionary, 2011 refers to “these materials cannot be decomposed into environmentally safe waste materials by the action of soil bacteria.” These harmful substances are toxic and take approximately four hundred years to break down, or in this case photo-degrade; which is how plastics made from (HDPE) break down. Since they are not biodegradable, they remain in the environment and are absorbed in soil or water (Indian Centre for Plastics in the Environment, 2010). This essay will discuss the various harmful effects of plastic bags, and demonstrate the risks that these bags impose on humans, animals and the environment. It will also discuss a series of suggested solutions that could help reduce plastic bag usage.
These fragments absorb all the toxins that pollute waterways, contaminate soil, and sicken animals (which are then consumed). Plastic trash also absorbs organic pollutants such as BPA. They take centuries to decompose while sitting in landfills, amounting to billions of environmentally poisonous time bombs. Bisphenol A (BPA) is a chemical compound used to create polycarbonate plastic and epoxy resins. Polycarbonate plastics are found in a wide range of products, but food and drink containers are the most concerning.
It is hypothesized that through laboratory studies, it will be provable that microplastic expansion has gotten worse over the years and is greatly impacting marine life. The results in this study supported the hypothesis of the research because it states: “Several million tonnes of plastics have been produced since the middle of the last century (more than two hundred million tonnes annually)”(Ivar do Sul, Costa, 2013). This has significance when looking at pollution because: “Microplastics are reportedly present on six continents, and higher amounts are commonly related to densely populated areas. In a study of the types (mostly fibers) and materials (frequently polyester and acrylic) of microplastics, suggested that the plastics were produced by sewage effluents, including wastewater from washing machines”(Ivar do Sul, Costa, 2013). These results indicate that pollution is present on six of the seven continents and it comes from largely populated areas.
According to Rahman (2007), fermentation is one of the earliest ancient traditions developed by cultures all around the world to prolong the possible storage time of foods. Moreover, it is a process in which microorganisms alter the sensory and functional properties of a food in order to come up with a desirable product for the consumer. It is also the process by which the chemical changes are brought about in an organic substrate or organic materials by means of the action of a biological catalyst known as enzyme.