Dissertation submitted in compliance with the requirements of the Master's Degree in Technology in Biotechnology, Durban Institute of Technology, 2003. / The measured kinetics of a bacterial culture degrading a single organic compound as a sole carbon source in a batch reactor depends on the history of the culture, the identifiability of the parameters, and the manner in which the experiment to measure them is run. The initial substrate to biomass ratio (So/Xo) used in the experiment is particularly important because it influences both parameter identifiability and the expression of the culture history. / M

Dissertation submitted in compliance with the requirements for the Master's Degree in Technology: Biotechnology, Durban Institute of Technology, 2004. / M

Fecal coliforms suspended in a natural stream water were exposed to rhodamine WT dye, chlorine and both in combination. Samples were analyzed for coliforms by three enumeration techniques. Statistical analyses of data by the paired-t test showed that for non-chlorinated samples no significant difference (0.10 level) was found between the recoveries by the three enumeration techniques. For chlorinated samples the standard membrane filter technique (Std-MF) yielded significantly lower recoveries (0.05 level) than the standard MPN procedure. A modified membrane filter technique employing a two-layer agar and a five hour 35°C preincubation period (Mod-MF) was found to yield recoveries consistently greater (0.05 level) than the standard MF technique. The data showed that exposing fecal coliforms to 100 to 1,000 ppb of rhodamine WT dye for 30 minutes, did not inhibit the recovery or enumeration of the organisms by any of the three assay methods. The number of fecal coliforms that survived exposure to 0.2 to 0.3 ppm of chlorine and 10 to 100 ppb of dye was not significantly different from the number enduring contact with similar concentrations of chlorine alone. / Master of Science

Thesis (M.Tech.: Biotechnology)-Dept. of Biotechnogy, Durban Institute of Technology, 2005 xvi, 85 leaves : ill. ; 31 cm / Atmospheric nitrogen pollution is on the increase and human activities are directly or indirectly responsible for the generation of the various nitrogen polluting compounds. This can lead to the two major problems of eutrophication and groundwater pollution. Therefore, the removal of nutrients such as nitrogen and phosphorus from wastewater is important. Nitrogen removal from wastewater is achieved by a combination of nitrification and denitrification. Thus, there is a need to identify and characterise heterotrophic denitrifying bacteria involved in denitrification in wastewater treatment systems. The aim of this study, therefore, was to characterise heterotrophic denitrifying bacteria through detailed biochemical and molecular analysis, to facilitate the understanding of their functional role in wastewater treatment systems. Drysdale (2001) isolated heterotrophic denitrifiers to obtain a culture collection of 179 isolates. This culture collection was used to screen for nitrate and nitrite reduction using the colorimetric biochemical nitrate reduction test. The isolates were thereafter Gram stained to assess their gram reaction, cellular and colonial morphology. Based on these results identical isolates were discarded and a culture collection of approximately 129 isolates remained. The genetic diversity of the culture collection was investigated by the analysis of polymerase chain reaction (PCR)-amplified 16S ribosomal DNA (rDNA) fragments on polyacrylamide gels using denaturing gradient gel electrophoresis (DGGE). Thus DNA fragments of the same length but different nucleotide sequences were effectively separated and microbial community profiles of eight predominant isolates were created. Batch experiments were conducted on these eight isolates, the results of which ultimately confirmed their characterisation and placed them into their four functional groups i.e. 3 isolates were incomplete denitrifiers, 2 isolates were true denitrifiers, 2 isolates were sequential denitrifiers and 1 isolate was an exclusive nitrite reducer.

Thesis (D.Tech.: Biotechnology)-Dept. of Biotechnology, Durban University of Technology, 2008. xxiv, 322 leaves / Activated sludge models now in use worldwide for the design and operation of treatment systems use hypothetical concentrations of active organisms. In order to validate and calibrate model outputs, concentrations and activities of organisms responsible for nitrification and denitrification need to be reflected by actual measurements. This research has been initiated by the observation of an increasing gap of suitable techniques that exist in the direct measurement and separation of active biomass components, responsible for COD removal and denitrification.

Antibiotic resistance profiles of fecal coliform isolated from unchlorinated and chlorinated secondary effluent were determined. Of 332 fecal coliforms isolated from chlorinated effluent a mean of 48% were multiply antibiotic resistant. In contrast, of 347 fecal coliforms isolated from unchlorinated effluent a mean of 29% were multiply antibiotic resistant. Resistance to ampicillin, cephalothin, and carbenicillin were significantly higher in the former than the latter. Randomly selected isolates survived and/or grew in sterile and unsterile effluent retaining resistance patterns for 40 days. Resistance factors were transferred in laboratory medium at frequencies from 0 to 1.2 x 10⁻² (number of recombinants/number of recipients) and in sterile neutralized tertiary effluent at frequencies from 0 to 1.0 x 10⁻⁴. Resuscitative techniques were necessary for optimal recovery of fecal coliforms from effluent using selective media. Antibiotic resistance patterns of fecal coliforms isolated from unchlorinated and chlorinated effluent was not associated with chlorine or heavy metal resistance. Multiply antibiotic resistant fecal coliforms from chlorinated effluent were significantly less sensitive to lytic phage than multiply antibiotic sensitive fecal coliforms from unchlorinated effluent (p < .05). Using group discriminate analysis of data, phage typing techniques were shown to be a potential tool for tracing fecal contamination of groundwater.

No description available.

Dissertation submitted in compliance with the requirements for the Master's Degree in Technology: Biotechnology, Technikon Natal, 2001. / Landfills play an important role in the removal of waste from the surroundings. There is a limit to the types of waste that can be recycled and the landfill becomes the final method of waste disposal. Because waste constitutes a wide variety of materials, the microbial consortia that develop within a landfill will be equally varied, depending on the type of waste deposited, the temperature of the landfill and moisture content of the waste. The metabolism of these microbial consortia can result in products that are either harmful or beneficial. In order to increase the pool of knowledge on landfill microbiology, it is important to study the various consortia that inhabit the landfill to determine the various microbial interactions that occur and subsequently to manipulate these interactions to enhance the benefits of a landfill site and reduce the harmful effects. In this research, an attempt was made to isolate anaerobic cellulolytic bacteria from a landfill site. Six waste samples, varying in age were obtained over a period of two years. Samples were excavated from a maximum depth of 4m. Samples are processed in anaerobic, phosphate buffer and cultivated in various pre-reduced anaerobic media and incubated under anaerobic conditions. Samples were also collected from other potential anaerobic sites namely, anaerobic sludge, decomposing bagasse, compost, manure, rumen and pond sediment. Results of degradation of the cellulose source (Whatman No. 1 filter paper) indicated that it was possible to cultivate cellulose-degrading microorganisms from the landfill. Zones of clearing around colonies, which would be indicative of cellulose degradation on solid media, were not obtained. Samples from the anaerobic sludge, compost and rumen showed degradation of cellulose in liquid media but not on solid media. It is concluded that the solid media used was unsuitable for the cultivation of anaerobic, cellulolytic bacteria or that the anaerobic conditions employed were not adequate to initiate the growth of the anaerobic cellulolytic bacteria. / M

Thesis (M.Tech.: Biotechnology)-Dept. of Biotechnogy, Durban Institute of Technology, 2005 xvi, 85 leaves : ill. ; 31 cm / Atmospheric nitrogen pollution is on the increase and human activities are directly or indirectly responsible for the generation of the various nitrogen polluting compounds. This can lead to the two major problems of eutrophication and groundwater pollution. Therefore, the removal of nutrients such as nitrogen and phosphorus from wastewater is important. Nitrogen removal from wastewater is achieved by a combination of nitrification and denitrification. Thus, there is a need to identify and characterise heterotrophic denitrifying bacteria involved in denitrification in wastewater treatment systems. The aim of this study, therefore, was to characterise heterotrophic denitrifying bacteria through detailed biochemical and molecular analysis, to facilitate the understanding of their functional role in wastewater treatment systems. Drysdale (2001) isolated heterotrophic denitrifiers to obtain a culture collection of 179 isolates. This culture collection was used to screen for nitrate and nitrite reduction using the colorimetric biochemical nitrate reduction test. The isolates were thereafter Gram stained to assess their gram reaction, cellular and colonial morphology. Based on these results identical isolates were discarded and a culture collection of approximately 129 isolates remained. The genetic diversity of the culture collection was investigated by the analysis of polymerase chain reaction (PCR)-amplified 16S ribosomal DNA (rDNA) fragments on polyacrylamide gels using denaturing gradient gel electrophoresis (DGGE). Thus DNA fragments of the same length but different nucleotide sequences were effectively separated and microbial community profiles of eight predominant isolates were created. Batch experiments were conducted on these eight isolates, the results of which ultimately confirmed their characterisation and placed them into their four functional groups i.e. 3 isolates were incomplete denitrifiers, 2 isolates were true denitrifiers, 2 isolates were sequential denitrifiers and 1 isolate was an exclusive nitrite reducer.

Thesis (D.Tech.: Biotechnology)-Dept. of Biotechnology, Durban University of Technology, 2008. xxiv, 322 leaves / Activated sludge models now in use worldwide for the design and operation of treatment systems use hypothetical concentrations of active organisms. In order to validate and calibrate model outputs, concentrations and activities of organisms responsible for nitrification and denitrification need to be reflected by actual measurements. This research has been initiated by the observation of an increasing gap of suitable techniques that exist in the direct measurement and separation of active biomass components, responsible for COD removal and denitrification.