Yevgeny Aster T. Dulla, Ness Jerold A. Justo, Jireh Joy D. Sacramento (February 2006)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
Although most plastics are considered non-biodegradable, recent researchers have shown that even plastics that are commonly considered as non-biodegradable still has a possibility to be degraded if the right microbial strain can be isolated and used in the biodegration process.
This study explores the biodegradability of commonly used plastics polyethylene, polypropylene, and cellophane by the bacteria Bacillus stearothermophilus at various temperatures (30°C, 55°C and 70°C).
The plastics strip were used as a replacement for the peptone in the Nutrient Broth medium. They served as the carbon source for the bacteria that were then inoculated into the broth. The same preparation without the bacteria served as the control. All the set-ups were incubated for 16 weeks after which, percentage weight losses of the plastic strips were determined.
Results of the study showed that all the treated and untreated plastics underwent degradation as shown by the percentage weight losses which ranged from 0.162% to 8.32%.
Paired t-test to compare the treated and untreated samples of three plastic types showed that only Polypropylene expose to 55°C temperature showed a significant difference in mean percentage weight losses. This means that of the three plastic types treated with Bacillus stearothermophilus amd exposed to three different temperatures, only Polypropylene at 55°C is biodegradable by the Bacillus stearothermophilus.