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Thesis (Ph. D.)--University of Kentucky, 2008. / Title from document title page (viewed on May 13, 2008). Document formatted into pages; contains: vi, 82 p. : ill. Includes abstract and vita. Includes bibliographical references (p. 76-81).

Thesis--Auburn University, 2009. / Abstract. Vita. Includes bibliographical references (p. 39-48).

Low-grade coal, a poor source of energy, has long been regarded as waste material by the coal mining industry. Biological degradation of this coal material by ligninolytic fungal strains presents a viable strategy towards eliminating this unusable fossil fuel. To this end, a novel and patented bioprocess termed Fungcoal was developed. Fungcoal is a biological process utilised in the in situ treatment of waste coal and is based on the mutualistic relationship between the fungus Neosartorya fischeri and the graminaceous species Cynodon dactylon. The process facilitates the rapid conversion of waste coal into soil-like material that stimulates establishment of vegetation for eventual coal dump rehabilitation. While a number of in vitro studies have identified various fungal strains as efficient coal degraders, the mechanisms involved in the Fungcoal-stimulated degradation process have not been fully elucidated. Furthermore, implementation of Fungcoal at both pilot and commercial scale has not been achieved. Thus the objective of this work was to investigate Fungcoal as a bioprocess via examining the role of coal degrading fungi (CDF) and grasses as biocatalysts in coal biodegradation and for the self-cladding of waste coal dumps. Initially, waste coal degradation by N. fischeri, strain ECCN 84, was investigated, specifically focusing on the mechanisms underpinning the process. In vitro studies showed the addition of waste coal induced active fungal colonisation resulting in increased fungal biomass. Increased extracellular laccase (LAC) activity, occuring concomitantly with an increase in hyphal peroxisome proliferation, was also observed in the coal supplied fungal cultures. Analysis of the colonised waste coal revealed a time dependent reduction in the percentage weight of elemental carbon coupled with an increase in elemental oxygen. The results supported metabolism and degradation of waste coal by N. fischeri strain ECCN 84 and involvement of fungal extracellular laccase. The contribution of C. dactylon, a C4 grass species to in situ biodegradation of waste coal in the presence of coal degrading and mycorrhizal fungi (MF) was also investigated. Enhanced degradation of the waste coal into a humic soil-like material was observed within the rhizosphere. Analysis of the resultant substrate revealed an increased concentration of highly oxidised humic-like substances (HS). Fungi remained viable in the rhizosphere up to 47 weeks post-inoculation and cultivation of C. dactylon, indicating the resultant humic substance-rich rhizosphere provided an environment conducive for microbial proliferation and activity. Furthermore, humic substance enrichment of waste coal substrates supported germination and seedling emergence of several agronomic species including Zea mays (corn), Phaseolus vulgaris (bean), Pisum sativum (pea), and Spinacia oleracea (spinach). Use of various cladding materials to support coal biodegradation, by fungus-grass mutualism and rehabilitation of waste dumps was evaluated at commercial scale. While substantial physico-chemical changes were not evident in the absence of cladding or where waste coal was used as cladding material, successful establishment of grass cover and diversity was achieved within three hydrological cycles on dumps cladded with weathered coal. Work presented in this thesis successfully demonstrates the degradation of waste coal by N. fischeri. The biodegradation process included enhanced extracellular LAC activity coupled with increased 3 waste coal oxidation. Increased HS concentration of waste coal substrate supported germination and early seedling establishment of several agronomic species. At commercial scale a co-substrate in the form of carbon-rich weathered coal was essential to support fungus-grass mutualism and Fungcoal-induced rehabilitation. These findings support the developed Fungcoal concept and the underpinning rationale that the phyto-biodegradation of waste coal indeed depends on the mutualistic interactions between grass root exudates and the ligninolytic and mycorrhizal fungi. Taken together, these findings provide practical evidence of the contribution of fungi and grasses as mutualists in the biodegradation of waste coal and sustainable rehabilitation of waste coal dumps

Fundamental processes involved in the microbial degradation of coal and its derivatives have been well investigated and documented over the past two decades. However, limited progress in industrial application has been identified as bottleneck in further active development of the field. The sporadic and unanticipated growth of Cynodon dactylon (Bermuda grass) has been observed on the surface of some coal dumps in the Witbank coal mining area of South Africa. Preliminary investigations showed the formation of a humic soil-like material from the breakdown of hard coal in the root zone of these plants. The potential of this system to contribute to industrial scale bioprocessing of hard coal was investigated. This study involved an investigation of the C. dactylon/coal rhizosphere environment and demonstrated the presence of fungal species with known coal bioconversion capability. Amongst these Neosartorya fischeri was identified and its activity in coal bioconversion was described for the first time. Cynodon dactylon plant roots were also shown to be colonized by mycorrhizal fungi including Glomus, Paraglomus and Gigaspora species. The role of plant photosynthate translocation into the root zone, providing organic carbon supplementation of fungal coal bioconversion was investigated in deep liquid culture with the N. fischeri isolate used as the biocatalyst. Organic acids, sugars and complex organic carbon sources were investigated and it was shown that glutamate provided significant enhancement of bioconversion activity in this system. The performance of N. fischeri in coal bioconversion was compared with Phanaerochaete chrysosporium and Trametes versicolor, both previously described fungal species in the coal bioconversion application. Fourier transform infrared spectroscopy indicated more pronounced oxidation and introduction of nitro groups in the matrix of the humic acid product of coal bioconversion in N. fischeri and P. chrysosporium than for T. versicolor. Macro-elemental analysis of biomass-bound humic acid obtained from the N. fischeri catalyzed reaction showed an increase in the oxygen and nitrogen components and coupled with a reduction in carbon and hydrogen. Pyrolysis gas chromatography mass spectroscopy further supported the proposal that the mechanism of bioconversion involves oxygen and nitrogen insertion into the coal structure. The C. dactylon bituminous hard coal dump environment was simulated in a fixed-bed perfusion column bioreactor in which the contribution of organic supplement by the plant/mycorrhizal component of the system was investigated. The results enabled the proposal of a descriptive model accounting for the performance of the system in which the plant/mycorrhizal component introduces organic substances into the root zone. The non-mycorrhizal fungi utilize the organic carbon supplement in its attack on the coal substrate, breaking it down, and releasing plant nutrients and a soil-like substrate which in turn enables the growth of C. dactylon in this hostile environment. Based on these results, the Stacked Heap Coal Bioreactor concept was developed as a large-scale industrial bioprocess application based on heap-leach mineral processing technology. Field studies have confirmed that bituminous hard coal can be converted to a humic acid rich substrate in a stacked heap system inoculated with mycorrhizal and N. fischeri cultures and planted with C. dactylon.

no abstract provided by author / Master of Science