Page 14 - KVIS Book

ENS04I

BIODEGRADATION OF POLYETHYLENE BY BACILLUS SUBTILIS
IN ANAEROBIC CONDITION AND EXTRACT ENZYME FROM
BACILLUS SUBTILIS

Kanthamart Khlaikun, Natnicha Sukploy, Nicharee Wangpolpattanasiri
Kamnoetvidya Science Academy, Thailand
Supervisor: Janjira Maneesan
Email: 5900024@kvis.ac.th

Nowadays, there are a lot of problems about plastic trash, so there are many ways to
destroy plastic such as landfilling, recycle, and incineration etc. Those ways have many
disadvantages; the disadvantage of landfilling is that it used very long time to degrade,
for incineration, if the heat is not enough, the toxic gases will occur which cause air
pollution. However, there is one way to destroy plastic called biodegradation.
Biodegradation is the process by which organic substances are decomposed by
microorganisms. Microorganisms will use carbon source from plastic. In anaerobic
condition, the products are methane, carbon dioxide, and water. Methane can be used
as fuel or else. Bacillus subtilis is chosen to degrade polyethylene which is the one of
plastic trash that can found in our daily life. Polyethylene degradation was occurred in
anaerobic condition in 32 degree celsius on shaker 90-120 revolutions per minute. We
collected the data every 7 days by monitoring the surface of HDPE after the
degradation via using scanning electron microscope (SEM). Comparing to the surface
of polyethylene before degrading and the negative control, the result shows that the
surface of HDPE degraded 14 days in nutrient broth pH 7.0 with Bacillus subtilis has
some shallow hole. Moreover, the surfaces of polyethylene that was degraded by
extracted protein from bacteria for 17 days show some change after using SEM.

Keywords: Biodegradation, Polyethylene, Anaerobic condition