Bioreduction of selenite and tellurite by Phanerochaete chrysosporium

Content: 1 General introduction  1.1 Background 1.2 Problem statement 1.3 Research objectives 1.4 Structure of the thesis 1.5 References    2 Literature review 2.1 Introduction 2.2 Fungal pellets 2.2.1 Fungal pellets: formation and growth 2.2.2 Factors influencing the characteristics and formation of pellets 2.2.3 Fungal pellets in bioreactors 2.3 Fungal pelleted bioreactors for wastewater treatment 2.3.1 Potential applications and challenges 2.3.2 Reactor configurations 2.3.3 Reactor design for fungal pelleted reactors 2.3.4 Sterile versus non-sterile conditions 2.3.5 Biomass recycle in fungal pelleted reactors 2.4 Removal of organic and inorganic pollutants 2.4.1 Removal of organic pollutants 2.4.2 Removal of inorganic pollutants 2.5 Scope for further research 2.6 Conclusions 2.7 References    3 Effects of selenium oxyanions on the fungus Phanerochaete chrysosporium 3.1 Introduction  3.2 Materials and methods  3.2.1 Fungal culture and medium composition  3.2.2 Batch experiments  3.2.3 Transmission electron microscopy (TEM) and electron-energy loss spectroscopy (EELS) analysis  3.2.4 Analytical methods  3.3 Results  3.3.1 Fungal interaction with selenium oxyanions  3.3.2 Effect of glucose concentration  3.3.3 Effect of pH  3.3.4 Effects of selenium concentration  3.4 Discussion  3.4.1 Inhibition of fungal growth induced by selenium oxyanions  3.4.2 Morphological effects induced by selenium oxyanions  3.4.3 Removal of selenium oxyanions by P. chrysosporium  3.4.4 Production of Se0 by P. chrysosporium  3.4.5 Potential applications  3.5 References     4 Removal of selenite from wastewater in a Phanerochaete chrysosporium pellet based fungal bioreactor  4.1 Introduction  4.2 Materials and methods  4.2.1 Strain, medium composition and pre-cultivation of fungal cultures  4.2.2 Bioreactor configuration and operating conditions  4.2.3 Analytical methods  4.2.4 Statistical analysis 4.3 Results  4.3.1 Bioreactor operation in batch mode  4.3.2 Continuous bioreactor operation at constant selenium concentrations  4.3.3 Bioreactor response to spikes of selenium concentration  4.3.4 Evolution and growth of the fungal biomass  4.4 Discussion  4.4.1 Removal of selenite in a fungal pelleted bioreactor  4.4.2 Response of the system to selenium spikes  4.4.3 Fungal morphology in the bioreactor  4.4.4 Operational advantages of fungal pelleted reactors  4.4.5 Longevity of reactor operation  4.5 Conclusions  4.6 References     5 Sorption of zinc onto elemental selenium nanoparticles immobilized in Phanerochaete chrysosporium pellets  5.1 Introduction  5.2 Experimental  5.2.1 Biosorbent preparation  5.2.2 Biosorbent characterization  5.2.3 Batch adsorption experiments  5.2.4 Analytical methods 5.3 Results  5.3.1 Characterization of biosorbent material  5.3.2 Effects of operational parameters on sorption capacity of nSe0-pellets  5.3.3 Sorption kinetics  5.3.4 Adsorption isotherms  5.4 Discussion  5.4.1 Sorption mechanisms of Zn onto nSe0 pellets  5.4.2 Effects of operational parameters on sorption capacity of nSe0-pellets  5.4.3 Potential applications  5.4.4 Conclusions  5.5 References     6 Effect of selenite on the morpholoy and respiratory activity of Phanerochaete chrysosporium biofilms  6.1 Introduction  6.2 Materials and methods  6.2.1 Fungal strain and culturing conditions  6.2.2 Biofilm growth and exposure experiments  6.2.3 Microsensor measurements  6.2.4 Biofilm sectioning and imaging  6.2.5 Analytical methods  6.3 Results  6.3.1 Influence of short-term SeO3 2- exposure on P. chrysosporium biofilm activity  6.3.2 Influence of long-term SeO3 2- exposure on P. chrysosporium biofilm activity 6.4 Discussion  6.4.1 Inhibition of developed P. chrysosporium biofilms by SeO3 2-  6.4.2 Influence of SeO3 2- on the physical and morphological properties of P. chrysosporium biofilms  6.5 Conclusions  6.6 References     7 Biomineralization of tellurium and selenium-tellurium nanoparticles by the white-rot fungus Phanerochaete chrysosporium  7.1 Introduction  7.2 Materials and methods  7.2.1 Fungal strain and culturing conditions  7.2.2 Batch experiments  7.2.3 Characterizations of fungal morphology  7.2.4 Analytical methods  7.3 Results  7.3.1 Fungal interaction with chalcogen oxyanions  7.3.2 Effect of Se:Te ratio on tellurite reduction  7.3.3 Fungal morphology  7.3.4 Electron microscopic analysis  7.4 Discussion  7.4.1 P. chrysosporium as a tellurite-reducing organism  7.4.2 Synergetic effect of selenite and tellurite on P. chrysosporium  7.4.3 Morphological effects induced by tellurite and Se-Te combinations  7.4.4 Production of nTe0 and nSe-Te  7.5 Conclusions  7.6 References     8 Mycotechnology for the treatment of Se and Te contaminated effluents and biomineralization of Se0 and Te0 nanoparticles  8.1 Mycotechnology  8.2 Fungal technology in the removal of Se and Te from wastewater  8.3 Fungi as Se0 and Te0 nanofactories  8.4 Novel hybrid fungal sorbents containing nanoparticles for wastewater  8.5 Fungal technology for the removal of selenium and potential applications of the Se0 nanoparticles immobilized in fungal pellets  8.6 Conclusions and future perspectives  8.7 References     Appendix 1