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Browsing by Author "Harrison, Susan T L"

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Investigating the effect of acid stress on selected mesophilic micro-organisms implicated in bioleaching

Author: Ngoma, I Emmanuel ; Ojumu, Tunde V ; Harrison, Susan T L Date: 01 May 2015 During start-up of heap bioleaching, low grade ores are typically treated with acid for agglomeration and to combat the acid neutralising capacity of the gangue minerals. This may stress the bioleaching inocula, particularly upon inoculation ... Read more c b n d
Investigation and in situ visualisation of interfacial interactions of thermophilic microorganisms with metal-sulphides in a simulated heap environment

Author: Africa, Cindy-Jade ; van Hille, Robert P ; Sand, Wolfgang ; Harrison, Susan T L Date: 2013 This study sought to provide a better understanding of the dynamics of microbial-metal sulphide interfacial processes relevant to heap bioleaching. Attachment and subsequent biofilm formation by Metallosphaera hakonensis (M. hakonensis) on ... Read more
Investigation of microbial metal-sulfide interfacial environments under mineral bioleach simulated conditions

Author: Africa, Cindy-Jade Date: 2017 This research pertains to bioleaching of copper containing ores with particular reference to the copper sulfide mineral chalcopyrite (CuFeS2). While it is focused on heap bioleaching, it has applications to stirred tank bioleaching operations. ... Read more
Kinetic analysis of biological sulphate reduction using lactate as carbon source and electron donor: Effect of sulphate concentration.

Author: Oyekola, Oluwaseun O ; van Hille, Robert P ; Harrison, Susan T L Date: 2010 This study investigated the effect of feed sulphate concentration on the kinetics of anaerobic sulphate reduction by a mixed SRB culture, using lactate as the sole carbon source and electron donor. Chemostat cultures were operated across a ... Read more
Lipid productivity as a key characteristic for choosing algal species for biodiesel production

Author: Griffiths, Melinda J ; Harrison, Susan T L Date: 2009 Microalgae are a promising alternative source of lipid for biodiesel production. One of the most important decisions is the choice of species to use. High lipid productivity is a key desirable characteristic of a species for biodiesel production. ... Read more
Lipid productivity, settling potential and fatty acid profile of 11 microalgal species grown under nitrogen replete and limited conditions

Author: Griffiths, Melinda J ; van Hille, Robert P ; Harrison, Susan T L Date: 2012 Microalgae are a promising alternative source of oil for biodiesel production. Identification of a species with desirable characteristics is a key component towards achieving economic feasibility for the process. This has been compromised by ... Read more
The lysis of Gram-negative Alcaligenes eutrophus by enzymes from Cytophaga

Author: Harrison, Susan T L ; Chase, Howard A ; Dennis, John S Date: 1991 The use of Cytophaga lysing enzymes was investigated for the liberation of poly-~- hydroxybutyrate (PHB) granules from the Gram-negative bacterium AlcaIigenes eutrophus. Complete cell lysis was approached within a 60 minute period. Contrary ... Read more
Magnetic resonance imaging characterisation of the influence of flowrate on liquid distribution in drip irrigated heap leaching

Author: Fagan-Endres, Marijke A ; Harrison, Susan T L ; Johns, Michael L ; Sederman, Andrew J Date: Dec 2015 Liquid irrigation is one of the key process control parameters following the construction of an ore leaching heap. This study uses 3D magnetic resonance imaging (MRI) to examine non-invasively the effect of liquid flowrate changes on heap ... Read more c b n d
The microbial ecology of moderately thermophilic mineral leaching reactors: the effect of solids loading and organic carbon supplementation on reactor performance

Author: Dean, Jonathan ; van Hille, Robert P ; Harrison, Susan T L Date: Nov 2015 Tank bioleaching of refractory sulphidic gold ores is well established, with potential to expand application to base metal concentrates. With increasing commercial tank bioleaching operations, understanding their microbial consortia is essential ... Read more
The microbial ecology of moderately thermophilic mineral leaching reactors: the effect of solids loading and organic carbon supplementation on reactor performance

Author: Dean, Jonathan ; van Hille, Robert P ; Harrison, Susan T L Date: 2015 Tank bioleaching of refractory sulphidic gold ores is well established, with potential to expand application to base metal concentrates. With increasing commercial tank bioleaching operations, understanding their microbial consortia is essential ... Read more
A novel microwell-based analytical technique for studying ferrous iron biooxidation activity

Author: Meissner, Murray P ; Xu, Zhehua ; Jones, Gavin C ; Minnaar, Susanna H ; Harrison, Susan T L Date: 2014 The broad range of complexities in bioleaching includes the use of mixed microbial communities with diversity of species and strains with different windows of operating conditions. Empirical approaches to characterise these currently use ... Read more
The plasticisation of polyhydroxybutyrate in vivo

Author: Harrison, Susan T L ; Chase, Howard A ; Amor, Stuart R ; Bonthrone, Karen M ; Sanders, Jeremy K M Date: 1992 The influence of a variety of treatments on the mobility and crystallinity of poly(hydroxybutyrate) (PHB) in whole cells and native granules has been proved using 13C-n.m.r. spectroscopy and X-ray powder diffraction, and correlated with the ... Read more c b n d
Quantification of growth and colonisation of low grade sulphidic ores by acidophilic chemoautotrophs using a novel experimental system

Author: Govender, Elaine ; Bryan, Christopher G ; Harrison, Susan T L Date: 2013 Microbial colonisation of low grade sulphidic ores and subsequent growth in heap bioleaching systems has not been quantified rigorously. In this study, an experimental system simulating the sub-processes that occur at the agglomerate scale ... Read more
Study of anaerobic lactate metabolism under biosulphidogenic conditions

Author: Oyekola, Oluwaseun A ; van Hille, Robert P ; Harrison, Susan T L Date: 2009 Biological sulfate reduction (BSR) has been reported to have potential for the treatment of acid mine drainage (AMD). The provision of a suitable carbon source and electron donor for this process remains a challenge. Lactate offers potential ... Read more
Sulfide mineral induced oxidative stress as a limiting factor in tank bioleaching performance

Author: Jones, Gavin ; van Hille, Robert P ; Harrison, Susan T L Date: 2009 In tank bioleaching, decreasing particle size of milled concentrates has been shown to improve leaching performance owing to increased mineral surface area and mechanical activation effects of fine mineral particles. However, evidence suggests ... Read more
The effect of pH and dissolved organic carbon on the growth kinetics of Ac. cupricumulans JTC3 and L. ferriphilum HT pertinent to the BIOX® process

Author: Maritz, Leo Date: 2022 The BIOX® process was designed to pre-treat refractory gold-bearing concentrates to enable gold recovery. It, and related, processes are well accepted commercially. An iron- and sulfur-oxidizing microbial consortium provide lixiviants for ... Read more
The effect of sulfide concentrate mineralogy and texture on Reactive Oxygen Species (ROS) generation

Author: Jones, Gavin C ; Becker, Megan ; van Hille, Robert P ; Harrison, Susan T L Date: ROS The generation of Reactive Oxygen Species (ROS), H2O2 and radical dotOH, has been observed from sulfide mineral containing particles in acidic solutions. The implications of this phenomenon, as a potential microbial stress-causing effect, ... Read more
Value chain diversification in the sugar industry using quantitative economic forecasting models

Author: Ghafeer, Amna Date: 2021 The South African sugar industry is facing increasing pressure from global sugar markets where the price of sugar is significantly lower than in domestic markets, as well as from the implementation of the health levy which has resulted in ... Read more
Whole-cell hydroxylation of n-octane by Escherichia coli strains expressing the CYP153A6 operon

Author: Gudiminchi, Rama Krishna ; Randall, Charlene ; Opperman, Diederik J ; Olaofe, Oluwafemi A ; Harrison, Susan T L ; Albertyn, Jacobus ; Smit, Martha S Date: 2012 CYP153A6 is a well-studied terminal alkane hydroxylase which has previously been expressed in Pseudomonas putida and Escherichia coli by using the pCom8 plasmid. In this study, CYP153A6 was successfully expressed in E. coli BL21(DE3) by cloning ... Read more