Physical and biological treatments of polyethylene-rice starch plastic films

This study aimed to produce an industrial applicable thermo-stable alpha-amylase from marine Bacillus amyloliquefaciens which isolated and selected according to its significant enzyme production. The effect of different pH values and temperatures on the bacterial growth and the enzyme production was estimated using an experimental statistical design; maximum amylase production and bacterial growth was obtained at pH 7.0 and 50 degrees C. Some biodegradable polyethylene rice starch plastic films (PERS-P) were manufactured using 0, 2.5, 5, 7.5 and 10% starch concentrations. The biodegradability (reduction in the plastic elongation%) was tested using the exposure to UV radiation at lambda(300-400nm) (intensity of about 1000 W/m(2)) and the produced B. amyloliquefaciens thermo-stable alpha-amylase. A significant reduction in the elongation% of these biodegradable plastics was observed in both cases especially on testing the 10% PERS-P; they showed a reduction of 26% and 20%, respectively, compared to the untreated plastic films (180 +/- 5). (C) 2009 Elsevier B.V. All rights reserved.