Implications of fullerene-60 upon in-vitro LDPE biodegradation

Fullerene-60 nanoparticles were used for studying their influence upon the LDPE biodegradation efficiency of two potential polymer-degrading consortia comprising of three bacterial strains each. At a concentration of 0.01% (w/v) in minimal broth lacking dextrose, fullerene did not have any negative influence upon the consortial growth. However, fullerene was found to be detrimental for bacterial growth at higher concentrations (viz. 0.25%, 0.5% and 1%). Although, addition of 0.01% fullerene into the biodegradation assays containing 5 mg/ml LDPE subsided growth-curves significantly, but subsequent analysis of degraded products revealed enhanced biodegradation. Fourier transform infrared spectroscopy (FT-IR) revealed breakage and formation of chemical bonds along with introduction of nu C-O frequencies into hydrocarbon backbone of LDPE. Further, simultaneous thermogravimetric-differential thermogravimetry-differential thermal analysis (TG-DTG-DTA) revealed higher number of decomposition steps along with a 1,000-fold decrease in the heat of reactions (DeltaH) in fullerene-assisted biodegraded LDPE suggesting probable formation of multiple, macromolecular by-products. This is the first report whereby fullerene-60, which is otherwise considered toxic, has helped to alleviate polymer biodegradation process of bacterial consortia.