Browsing by Author "Faruq, Mohammad Omar"

In this research, lignocellulose decomposition and bioethanol production potentiality of the white rot fungus Phlebia radiata 79 was studied at different atmospheric conditions on several solid substrate mixtures containing spent brewery barley mash (SBBM), barley straw, spruce wood sawdust, and birch wood sawdust. The fungus was capable of growing on all substrate mixtures, subsequently converting them into fermentable sugars like glucose, producing various primary metabolites involving ethanol, acetate, and glycerol. Ethanol accumulation was always dominant under nitrogen flushed anaerobic conditions as well as semi-aerobic conditions. The highest concentration of ethanol accumulated on the second week of cultivation on all solid substrate mixtures. Under anaerobic conditions, the detected amount of ethanol was 88 mmol/l, 87 mmol/l, and 108 mmol/l, after two weeks of cultivation of the fungus on lignocellulose substrates containing SBBM mixed with barley straw, spruce wood sawdust, or birch wood sawdust, respectively. Under semi-aerobic conditions, corresponding concentrations of ethanol - 90 mmol/l, 61 mmol/l, and 105 mmol/l - accumulated in the cultures after two weeks of cultivation on the same substrate mixtures, respectively. Under aerobic conditions, only small amounts of ethanol were detected during the first two weeks of cultivation. Another part of the study was to establish an enzyme assay method for pectin degradation and conversion, in order to measure the activities of specific carbohydrate-active enzymes (CAZymes) involving pectinase, as well as cellulolytic β-glucosidase and cellobiohydrolase (CBH) activities. The highest β-glucosidase activity (5.2 nkat/ml) was observed under aerobic conditions in cultures on the substrate mixture of SBBM and barley straw. CBH activity was also prominent under aerobic conditions, and the maximal activity (0.7 nkat/ml) was detected on the substrate mixture of SBBM and spruce wood sawdust, while elevated pectinase activity (83 nkat/ml) was recorded under aerobic conditions on substrate mixtures containing SBBM and barley straw. Thus, the conclusions are that composition of the solid waste lignocellulose substrate mixture affected enzyme production by the fungus, whereas production of ethanol was mainly controlled by the cultivation atmosphere. Interestingly, both anaerobic and semi-aerobic atmospheric conditions supported similar bioconversion efficiency resulting with similar high levels of bioethanol production in the fungal cultures within two weeks.