This paper presents the results of an experimental study of the bacterial-mediated biodegradation of linear low density polyethylene (LLDPE) by Serratia marcescens subsp. marcescens (S. marcescens marcescens) bacterium without prior exposure of the LLDPE to thermooxidative aging. Degradation promoted by supernatant from S. marcescens marcescens was also studied, and compared to that promoted by direct exposure to S. marcescens marcescens cells. The results show that the cell-free extracts degrade LLDPE faster than the S. marcescens marcescens. The mechanisms of degradation are also elucidated via Scanning Electron Microscopy, Differential Scanning Calorimetry and Fourier Transform Infra-Red Spectroscopy. These methods show that the S. marcescens marcescens and its supernatant both degrade LLDPE. There was also an increase in the concentrations of the carbonyl groups (new peaks) after the microbial degradation of LLDPE. The degradation process results in the formation and growth of microvoids. The latter are also found to coalesce to form larger defects with increasing exposure to supernatant/cell-free extracts or S. marcescens marcescens.
The biosynthesis of gold nanoparticles fromNauclea latifolialeaf/plant extract is presented in this paper. The synthesis is shown to produce gold nanoparticles from hydrogen Tetra-chloro auric acid (HAuCl4) in less than 1 minute. The resulting gold nanoparticles are characterized using UV/Visible spectrophotometry (UV-Vis), Energy Dispersive X-ray Spectroscopy (EDX), Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM). The implications of the results are discussed for potential applications of biosynthesized gold nanoparticles in cancer detection and treatment.
This paper presents the biosynthesis of gold nanoparticles from the bacteria, Serratia marcescens.The intra-and extra-cellular synthesis of gold nanoparticles is shown to occur over a range of pH and incubation times in cell-free exracts and biomass ofserratia marcescensthat were reacted with 2.5mM Tetrachloroauric acid (HAuCl4). The formation of gold nanoparticles was identified initially via color changes from yellow auro-chloride to shades of red or purple in gold nanoparticle solutions. UV-Visible spectroscopy (UV-Vis), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray spectroscopy (EDS), Helium Ion Microscopy (HIM) and Dynamic Light Scattering (DLS) were also used to characterize gold nanoparticles produced within a range of pH conditions. The results show clearly that the production of gold nanoparticles from cell-free extracts require shorter times than the production of gold nanoparticles from the biomass.
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