Anaerobic ethanol production using bran as a substrate

Momoniat, Muniera
Journal Title
Journal ISSN
Volume Title
Biofuels have been exploited as a substitute for non-renewable fossil fuels by humankind for several decades. The source has been mainly plants that are also used to make other important economic products. It is therefore important to investigate other less costly methods of producing this important environmentally friendly fuel. The purpose and focus of this research were threefold; to isolate a thermophilic and mesophilic (control) mixed bacterial consortium that degrades lignocellulose efficiently and produces ethanol, to run an anaerobic fluidised bed bioreactor (AFBR) that produces ethanol and to use molecular methods to identify the bacterial species making up the consortia. Winogradsky columns were used as enrichment culture, and a microaerophilic culture technique was employed to isolate cultures that took from 5 days for complete filter paper degradation (mesophilic and thermophilic). Thermophilic and mesophilic bacterial consortia were constructed from a few of the fastest degrading cultures. The mesophilic consortium isolated was run in an AFBR. The thermophilic consortium (65°C) was obtained from freshly collected elephant, impala, eland and kudu dung collected at the Johannesburg zoo was mixed and inoculated into endo medium and incubated at 65°C. The AFBR was optimised and operated under mesophilic and thermophilic conditions by obtaining a steady reduction in the settled bed volume, indicating cellulolytic degradation of the fluidised bran bed and ethanol production. The population structure of the bacterial consortia was determined using molecular techniques: polymerase chain reaction amplification of ribosomal rDNA using universal markers and DGGE was used to separate species into separate bands (species), indicating the similarity and differences in the population structures in the thermophilic, mesophilic and reactor samples. The result of this study show that the Winogradsky column as well as termites can be exploited as a source bacteria consortia for ethanol production
A dissertation submitted in fulfilment of the requirements for the degree of Master of Science in Molecular and Cell Biology in the Faculty of Science, University of the Witwatersrand, Johannesburg, 2020