Colonization and Microbial Degradation of Polyisoprene Rubber by Nocardioform Actinomycete Nocardia sp. strain-MBR

A bacterium isolated from old tire sample in Alexandria, Egypt, was shown to be able to utilize natural rubber and other isoprenoide compounds as a sole source for carbon and energy. Taxonomic analysis of the strain based on morphological and physiological studies indicated that the bacterium belongs to nocardioform actinomycete Nocardia sp. strain-MBR. Degradation behavior as well as SEM examinations indicated that the strain grow adhesively and depends on direct contact with the rubber substrate so belongs to the CMN group. Semicontinuous degradation of NR granules resulted in approximately 7% increase in percent CO2 release during growth. Schiff`s reagent staining revealed that the bacterium showed a higher colonization efficiency on small and treated pieces of NR-latex gloves, while a lower colonization efficiency when grown on large and nontreated NR-latex gloves. Formation of bacterial films and occurrence of compounds containing aldehyde groups during cultivation was also confirmed. Degradation of synthetic rubbers as well as other acyclic isoprenoids and compounds of analogous structure namely, phytol, squalene, squalane and prostane was recognized indicating that the bacterium has the metabolic capability to utilize these compounds as sole carbon source.