The remnant floral diversity of a naturally reclaimed area proximal to an abandoned mine was asse... more The remnant floral diversity of a naturally reclaimed area proximal to an abandoned mine was assessed. The coal mine site, the Incident zone (IZ) and an unsullied site, the Control zone (CZ), were sampled. Using a 5 m2 quadrat, the floristic composition was determined by the occurrence, distribution analysis, and species diversity indices. The study revealed a degraded vegetation type and recorded a total of 60 species, 53 genera and 27 families. Both the IZ and CZ shared 26.67% species similarity, while 36.67% are were unique to each zone. Five species were dominant (Ageratum conyzoides, Panicum maximum, Calopogonium mucunoides, Chromolaena odorata). While the dominant genera vary between IZ (Borreria, Dioscorea, Ipomoea, and Phyllanthus) and CZ (Desmodium, Euphorbia, and Ipomoea), Asteraceae and Poaceae were the dominant families in both zones. Forbs were the most dominant life forms in both zones; Cyclosorus sp. and Adiantum sp. were only found on the IZ, whereas, Kyllinga erecta...
The rhizospheres of the weeds Ageratum conyzoides, Axonopus compressus, Emilia coccinea, Synedrel... more The rhizospheres of the weeds Ageratum conyzoides, Axonopus compressus, Emilia coccinea, Synedrella nodiflora, Urena lobata and Sida acuta from a sub-bituminous coal mining site and a control site, without coal discards, were screened for new fungi with ability to degrade sub-bituminous coal in the laboratory. The isolates were identified by cultural and molecular methods. Seventeen out of the sixty-one fungal isolates tested could utilize sub-bituminous coal as an energy source. Upon further evaluation, only seven of these were promising candidates for coal biodegradation, and they were assayed for their biosolubilization and depolymerization activities to determine their mechanisms of coal biodegradation. Based on the accumulation of humic acid (HA), which is the marker for biosolubilization, Mucor circinelloides and Aspergillus tubingensis were the most active. On the other hand, Cunninghamella bertholletiae, Simplicillium subtropicum, Penicillium daleae and Trichoderma koningiop...
Cynodon dactylon (Bermuda grass) has been observed to grow sporadically on the surface of coal du... more Cynodon dactylon (Bermuda grass) has been observed to grow sporadically on the surface of coal dumps in the Witbank coal mining area of South Africa. Root zone investigation indicated that a number of fungal species may be actively involved in the biodegradation of hard coal, thus enabling the survival of the plant, through mutualistic interaction, in this extreme environment. In an extensive screening program of over two thousand samples, the Deuteromycete, Neosartorya fischeri, was isolated and identified. The biodegradation of coal by N. fischeri was tested in flask studies and in a perfusion fixed-bed bioreactor used to simulate the coal dump environment. The performance of N. fischeri was compared to Phanaerochaete chrysosporium and Trametes (Polyporus) versicolor, previously described in coal biodegradation studies. Fourier transform infrared spectrometry and pyrolysis gas chromatography mass spectrometry of the biodegradation product indicated oxidation of the coal surface and nitration of the condensed aromatic structures of the coal macromolecule as possible reaction mechanisms in N. fischeri coal biodegradation. This is a first report of N. fischeri-mediated coal biodegradation and, in addition to possible applications in coal biotechnology, the findings may enable development of sustainable technologies in coal mine rehabilitation.
This review focuses on ligninolytic fungi, soil bacteria, plants and root exudates in the degrada... more This review focuses on ligninolytic fungi, soil bacteria, plants and root exudates in the degradation and solubilisation of low grade and waste coal and the interaction between these mutualistic biocatalysts. Coal represents a considerable portion of the total global fossil fuel reserve and continued demand for, and supply of this resource generates vast quantities of spoil and low grade waste. Large scale bioremediation technologies for the beneficiation of waste coal have unfortunately not yet been realised despite the many discoveries of microorganisms capable of lignite, lignin, and humic acid breakdown. Even so, solubilisation and depolymerization of low grade coal appears to involve either ligninolytic enzyme action or the production of alkaline substances or both. While the precise mechanism of coal biosolubilisation is unclear, a model for the phyto-biodegradation of low rank coal by mutualistic interaction between ligninolytic microorganisms and higher plants is proposed. Based on accumulated evidence this model suggests that solubilisation and degradation of lignite and waste coals commences upon plant root exudate and ligninolytic microorganism interaction, which is mutualistic, and includes soil bacteria and both mycorrhizal and non-mycorrhizal fungi. It is envisaged that this model and its further elaboration will aid in the development of functional technologies for commercial bioremediation of coal mine spoils, contribute to soil formation, and the overall biogeochemistry of organic carbon in the global ecosystem.
The remnant floral diversity of a naturally reclaimed area proximal to an abandoned mine was asse... more The remnant floral diversity of a naturally reclaimed area proximal to an abandoned mine was assessed. The coal mine site, the Incident zone (IZ) and an unsullied site, the Control zone (CZ), were sampled. Using a 5 m2 quadrat, the floristic composition was determined by the occurrence, distribution analysis, and species diversity indices. The study revealed a degraded vegetation type and recorded a total of 60 species, 53 genera and 27 families. Both the IZ and CZ shared 26.67% species similarity, while 36.67% are were unique to each zone. Five species were dominant (Ageratum conyzoides, Panicum maximum, Calopogonium mucunoides, Chromolaena odorata). While the dominant genera vary between IZ (Borreria, Dioscorea, Ipomoea, and Phyllanthus) and CZ (Desmodium, Euphorbia, and Ipomoea), Asteraceae and Poaceae were the dominant families in both zones. Forbs were the most dominant life forms in both zones; Cyclosorus sp. and Adiantum sp. were only found on the IZ, whereas, Kyllinga erecta...
The rhizospheres of the weeds Ageratum conyzoides, Axonopus compressus, Emilia coccinea, Synedrel... more The rhizospheres of the weeds Ageratum conyzoides, Axonopus compressus, Emilia coccinea, Synedrella nodiflora, Urena lobata and Sida acuta from a sub-bituminous coal mining site and a control site, without coal discards, were screened for new fungi with ability to degrade sub-bituminous coal in the laboratory. The isolates were identified by cultural and molecular methods. Seventeen out of the sixty-one fungal isolates tested could utilize sub-bituminous coal as an energy source. Upon further evaluation, only seven of these were promising candidates for coal biodegradation, and they were assayed for their biosolubilization and depolymerization activities to determine their mechanisms of coal biodegradation. Based on the accumulation of humic acid (HA), which is the marker for biosolubilization, Mucor circinelloides and Aspergillus tubingensis were the most active. On the other hand, Cunninghamella bertholletiae, Simplicillium subtropicum, Penicillium daleae and Trichoderma koningiop...
Cynodon dactylon (Bermuda grass) has been observed to grow sporadically on the surface of coal du... more Cynodon dactylon (Bermuda grass) has been observed to grow sporadically on the surface of coal dumps in the Witbank coal mining area of South Africa. Root zone investigation indicated that a number of fungal species may be actively involved in the biodegradation of hard coal, thus enabling the survival of the plant, through mutualistic interaction, in this extreme environment. In an extensive screening program of over two thousand samples, the Deuteromycete, Neosartorya fischeri, was isolated and identified. The biodegradation of coal by N. fischeri was tested in flask studies and in a perfusion fixed-bed bioreactor used to simulate the coal dump environment. The performance of N. fischeri was compared to Phanaerochaete chrysosporium and Trametes (Polyporus) versicolor, previously described in coal biodegradation studies. Fourier transform infrared spectrometry and pyrolysis gas chromatography mass spectrometry of the biodegradation product indicated oxidation of the coal surface and nitration of the condensed aromatic structures of the coal macromolecule as possible reaction mechanisms in N. fischeri coal biodegradation. This is a first report of N. fischeri-mediated coal biodegradation and, in addition to possible applications in coal biotechnology, the findings may enable development of sustainable technologies in coal mine rehabilitation.
This review focuses on ligninolytic fungi, soil bacteria, plants and root exudates in the degrada... more This review focuses on ligninolytic fungi, soil bacteria, plants and root exudates in the degradation and solubilisation of low grade and waste coal and the interaction between these mutualistic biocatalysts. Coal represents a considerable portion of the total global fossil fuel reserve and continued demand for, and supply of this resource generates vast quantities of spoil and low grade waste. Large scale bioremediation technologies for the beneficiation of waste coal have unfortunately not yet been realised despite the many discoveries of microorganisms capable of lignite, lignin, and humic acid breakdown. Even so, solubilisation and depolymerization of low grade coal appears to involve either ligninolytic enzyme action or the production of alkaline substances or both. While the precise mechanism of coal biosolubilisation is unclear, a model for the phyto-biodegradation of low rank coal by mutualistic interaction between ligninolytic microorganisms and higher plants is proposed. Based on accumulated evidence this model suggests that solubilisation and degradation of lignite and waste coals commences upon plant root exudate and ligninolytic microorganism interaction, which is mutualistic, and includes soil bacteria and both mycorrhizal and non-mycorrhizal fungi. It is envisaged that this model and its further elaboration will aid in the development of functional technologies for commercial bioremediation of coal mine spoils, contribute to soil formation, and the overall biogeochemistry of organic carbon in the global ecosystem.
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