Biodegradation of type-B gelatine by bacteria isolated from cinematographic films. A viscometric study

摘要

The biodegradation of photographic grade gelatine (Bloom 225) material has been studied by viscometry in aqueous solution (at 37degrees, 6.67%w/w) using bacteria isolated and identified from cinematographic film stored in different Spanish archives. From viscosity data, different variables such us molecular weight and chain scission were calculated using literature equations and the results were checked using two bloom gelatine grades of 75 and 225 g. In all the bioassay experiments the initial concentration of bacteria (25 X 10(6) cell/ml) remained constant and different temperatures (37, 30, 20 and 4 degreesC) were employed. From the 13 studied bacteria only six were gelatinase active. They were members of the genuses Bacillus (B. amyloliquefaciens, B. subtilis, B. megaterium, B. pichinotyi, B. pumilus) and Staphylococcus (S. horminis). Through the viscosity decay profiles with bioassay-time and the corresponding calculated chain scission, the relative quantitative gelatinase efficiency of these bacteria has been evaluated. The influence of the temperature on the biodegradation has also been determined and, at 4 degreesC only four species of Bacillus were active in the biodegradation of gelatine in the time scale of 3 months. A synergistic effect in the biodegradation of gelatine was observed with the natural mixture of Bacillus amyloliquefaciens and subtilis present in the cinematographic polymer sample. (C) 2004 Elsevier Ltd. All rights reserved.