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Friday, May 30, 2008

Bacteria that effectively transform plastic waste into a useful eco-friendly plastic:

Bacteria that effectively transform plastic waste into a useful eco-friendly plastic:

In response to problems associated with plastic waste and its effect on the environment, there has been considerable interest in the development and production of biodegradable plastics. Innumerable amount of research have also been conducted world wide to find out ways to convert synthetic plastic waste into biodegradable and compostable material. Their effort was to isolate bacterium that can effectively convert a waste plastic product into safe, biodegradable product or to make safe and biodegradable plastic, which can be used safely for further manufacture of some product.

A. It has been observed that, chemicals called Polyhydroxyalkanoates (PHAs) are polyesters that accumulate as inclusions in a wide variety of bacteria. These bacterial polymers have properties ranging from stiff and brittle plastics to rubber-like materials. Because of their inherent biodegradability, PHAs are regarded as an attractive source of nonpolluting plastics and elastomers that can be used for specialty and commodity products. They were the first biodegradable polyesters to be utilised in plastics. These aliphatic polyesters naturally produced via a microbial process on sugar-based medium. The two main members of the PHA family are polyhydroxybutyrate (PHB) and polyhydroxyvalerate (PHV).

B. There is good news that, recently some European scientists have discovered a bacterial strain that uses styrene, a toxic byproduct of the polystyrene industry, as fuel to make Polyhydroxyalkanoate (PHA) - biodegradable plastic. The microbes, a special strain of the soil bacterium Pseudomonas putida, convert polystyrene foam — commonly known as Styrofoam — into PHA, a biodegradable plastic. This is among the first to investigate the possibility of converting a petroleum-based plastic waste into a reusable biodegradable form.

Researchers utilized pyrolysis, a process that transforms plastic waste materials by heating them in the absence of oxygen, to convert polystyrene — the key component of many disposable products — into styrene oil. The researchers then supplied this oil to Pseudomonas putida, a bacterium that can feed on styrene, which converted the oil into PHA. The process might also be used to convert other types of discarded plastics into PHA.

C. PHA has numerous applications in medicine and can be used to make plastic kitchenware, packaging film and other disposable items as well. This biodegradable plastic is resistant to hot liquids, greases and oils, and can have a long shelf life. The advantageous side of PHA is unlike polystyrene, it readily breaks down in soil, water, septic systems and backyard composts. In other words, it is biodegradable and compostable.

D. Worldwide, more than 14 million metric tons of polystyrene are produced annually, most of this ends up in landfills producing pollution. Thus, this system can help transform plastic waste into a useful eco-friendly plastic, significantly reducing the environmental impact of this ubiquitous, but difficult-to-recycle waste stream.

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