title: Sequestration of metal and metalloid ions by thermophilic bacteria

authors: Hetzer, Adrian

subjects: biosorption

abstract: This Ph. D. thesis presents results and conclusions from studies 1) investigating the interaction between metal and metalloid ions and thermophilic bacteria, and 2) characterizing microbial populations in a geothermally active habitat with relatively high concentrations of metalloid ions and compounds.

In initial cadmium ion toxicity assays, the minimal inhibition concentration for 46 thermophilic bacteria of the genera Aneurinibacillus, Anoxybacillus, Bacillus, Brevibacillus, Geobacillus, and Thermus were determined. The highest tolerances to cadmium ions (Cd2+) in the range of 400 to 3200 micro;M were observed for species belonging to the genus Geobacillus. 

The thermophilic Gram-positive bacteria Geobacillus stearothermophilus and G. thermocatenulatus were selected to describe further biosorption reactions between cadmium ions and chemically reactive functional groups (potential ligands) within and onto the bacterial cell walls. Data obtained from electrophoretic mobility, potentiometric titration and cadmium ion adsorption experiments were used to quantify the number and concentrations of ligands and to determine the thermodynamic stability constants for the ligand-cation complexes. The first reported surface complexation models (SCMs) quantifying metal ion adsorption by thermophilic microorganisms predicted cadmium adsorption and desorption by both studied Geobacillus strains over a range of pH values and for different biomasses. The results indicated the functional group, with a deprotonation constant pK value of approximately 3.8, to be more dominant in cation biosorption accounting for 66 and 80% of all titrable groups for G. thermocatenulatus and G. stearothermophilus, respectively. The generated SCMs are different from model parameters obtained from mesophilic species that have been studied to date and might indicate a different biosorption behavior for both studied Geobacillus strains.

Another objective of this thesis was to characterize microbial populations in the hot spring Champagne Pool, located in Waiotapu, New Zealand. The thermal spring is approximately 65 m in diameter and discharges water at 75eg; C and pH 5.5, which is oversaturated with arsenic and antimony compounds that precipitate and form orange deposits. Recovered nucleic acids and adenosine 5'-triphosphate (ATP) concentrations obtained for Champagne Pool water samples indicated low microbial density and were in good agreement with relatively low cell numbers of 5.6 plusmn; 0.5 x10^6 cells per ml. Denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene clone library analyses revealed the abundance of Sulfurihydrogenibium, Sulfolobus and Thermofilum-like populations in Champagne Pool. 

Two novel bacteria and one novel archaeon were successfully isolated with a distant phylogenetic relationship to Sulfurihydrogenibium, Thermoanaerobacter, and Thermococcus, respectively. Genotypic and metabolic characteristics differentiated isolate CP.B2 from described species of the genus Sulfurihydrogenibium. CP.B2 represents a novel genus within the Aquificales order, for which the name Venenivibrio stagnispumantis gen. nov., sp. nov. is proposed. V. stagnispumantis is a thermophilic, chemolithothrophic bacterium, that utilizes molecular hydrogen as electron donor and oxygen as electron acceptor and displayed growth in the presence of up to 8 mM NaAsO2 (As3+) and more than 20 mM Na2HAsO4.7H2O (As5+). However, growth was not observed when Na2HAsO4.7H2O and NaAsO2 were provided as the sole electron acceptor and donor pair. Arsenic resistance was conferred by the genes arsA and arsB

text: Sequestration of metal and metalloid ions by thermophilic bacteria This Ph. D. thesis presents results and conclusions from studies 1) investigating the interaction between metal and metalloid ions and thermophilic bacteria, and 2) characterizing microbial populations in a geothermally active habitat with relatively high concentrations of metalloid ions and compounds.

In initial cadmium ion toxicity assays, the minimal inhibition concentration for 46 thermophilic bacteria of the genera Aneurinibacillus, Anoxybacillus, Bacillus, Brevibacillus, Geobacillus, and Thermus were determined. The highest tolerances to cadmium ions (Cd2+) in the range of 400 to 3200 micro;M were observed for species belonging to the genus Geobacillus. 

The thermophilic Gram-positive bacteria Geobacillus stearothermophilus and G. thermocatenulatus were selected to describe further biosorption reactions between cadmium ions and chemically reactive functional groups (potential ligands) within and onto the bacterial cell walls. Data obtained from electrophoretic mobility, potentiometric titration and cadmium ion adsorption experiments were used to quantify the number and concentrations of ligands and to determine the thermodynamic stability constants for the ligand-cation complexes. The first reported surface complexation models (SCMs) quantifying metal ion adsorption by thermophilic microorganisms predicted cadmium adsorption and desorption by both studied Geobacillus strains over a range of pH values and for different biomasses. The results indicated the functional group, with a deprotonation constant pK value of approximately 3.8, to be more dominant in cation biosorption accounting for 66 and 80% of all titrable groups for G. thermocatenulatus and G. stearothermophilus, respectively. The generated SCMs are different from model parameters obtained from mesophilic species that have been studied to date and might indicate a different biosorption behavior for both studied Geobacillus strains.

Another objective of this thesis was to characterize microbial populations in the hot spring Champagne Pool, located in Waiotapu, New Zealand. The thermal spring is approximately 65 m in diameter and discharges water at 75eg; C and pH 5.5, which is oversaturated with arsenic and antimony compounds that precipitate and form orange deposits. Recovered nucleic acids and adenosine 5'-triphosphate (ATP) concentrations obtained for Champagne Pool water samples indicated low microbial density and were in good agreement with relatively low cell numbers of 5.6 plusmn; 0.5 x10^6 cells per ml. Denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene clone library analyses revealed the abundance of Sulfurihydrogenibium, Sulfolobus and Thermofilum-like populations in Champagne Pool. 

Two novel bacteria and one novel archaeon were successfully isolated with a distant phylogenetic relationship to Sulfurihydrogenibium, Thermoanaerobacter, and Thermococcus, respectively. Genotypic and metabolic characteristics differentiated isolate CP.B2 from described species of the genus Sulfurihydrogenibium. CP.B2 represents a novel genus within the Aquificales order, for which the name Venenivibrio stagnispumantis gen. nov., sp. nov. is proposed. V. stagnispumantis is a thermophilic, chemolithothrophic bacterium, that utilizes molecular hydrogen as electron donor and oxygen as electron acceptor and displayed growth in the presence of up to 8 mM NaAsO2 (As3+) and more than 20 mM Na2HAsO4.7H2O (As5+). However, growth was not observed when Na2HAsO4.7H2O and NaAsO2 were provided as the sole electron acceptor and donor pair. Arsenic resistance was conferred by the genes arsA and arsB

year: 2007

title: Blu-ray cytometer

authors: Albugami, Naser

abstract: The flow cytometers are one of the most powerful devices used to measure the properties of individual particles passing through a sensing region. In this thesis, a low cost cytometer using a Blu-ray pickup is analysed and further developed. This includes the characterisation of the existing system and its performance as well as the evaluation of count rate for different flow rates and focuses. Based on that, the best parameters for measurement conditions have been determined. The system was set up for forward scatter as well as for fluorescence, both were to be measured at the same time and it was found that both could be recorded and counted. In addition, it was found that fluorescing particles can give a fluorescent count as well as scatter count and it was noticed that different sizes of non-fluorescent particles can produce scatter count. The count rate for a mixture of fluorescent and non-fluorescent particles was measured. This required the installation of two different amplifiers (for fluorescent and non-fluorescent particles) and building a new LabView program containing two channels.

In a later part of the thesis, the system was improved to progress towards a setup of avalanche photodiode as detector for forward scattering as well as fluorescence. This gives a very good counting accuracy of 90% at speed of 10μl/s. However, this counting accuracy drops to 80% at speed of 1μl/s when mixing fluorescent and non-fluorescent particles. The counting accuracy is the ratio (in percent) of the measured count to the actual one. As a new detection approach, a beam stop was installed in front of the photo detector so scattered laser light from particles was detected instead of a reduction of laser intensity. This part of the project proves Mie theory which states that the the forward scattered light is in the forward direction. To double check this result, a beam pass was installed in front of the photo detector and the calculated percentage of counting accuracy was very close to the one without a beam stop. It was also checked that the system was capable of detection fluorescent particle after the installation of a high bass filter which passes fluorescent wavelength signals (green) and blocks the blue ray signals. Finally, it was found that this system is able to detect small size particles, such as 1μm particles and to distinguish between 1μm and 10μm particles.

text: Blu-ray cytometer The flow cytometers are one of the most powerful devices used to measure the properties of individual particles passing through a sensing region. In this thesis, a low cost cytometer using a Blu-ray pickup is analysed and further developed. This includes the characterisation of the existing system and its performance as well as the evaluation of count rate for different flow rates and focuses. Based on that, the best parameters for measurement conditions have been determined. The system was set up for forward scatter as well as for fluorescence, both were to be measured at the same time and it was found that both could be recorded and counted. In addition, it was found that fluorescing particles can give a fluorescent count as well as scatter count and it was noticed that different sizes of non-fluorescent particles can produce scatter count. The count rate for a mixture of fluorescent and non-fluorescent particles was measured. This required the installation of two different amplifiers (for fluorescent and non-fluorescent particles) and building a new LabView program containing two channels.

In a later part of the thesis, the system was improved to progress towards a setup of avalanche photodiode as detector for forward scattering as well as fluorescence. This gives a very good counting accuracy of 90% at speed of 10μl/s. However, this counting accuracy drops to 80% at speed of 1μl/s when mixing fluorescent and non-fluorescent particles. The counting accuracy is the ratio (in percent) of the measured count to the actual one. As a new detection approach, a beam stop was installed in front of the photo detector so scattered laser light from particles was detected instead of a reduction of laser intensity. This part of the project proves Mie theory which states that the the forward scattered light is in the forward direction. To double check this result, a beam pass was installed in front of the photo detector and the calculated percentage of counting accuracy was very close to the one without a beam stop. It was also checked that the system was capable of detection fluorescent particle after the installation of a high bass filter which passes fluorescent wavelength signals (green) and blocks the blue ray signals. Finally, it was found that this system is able to detect small size particles, such as 1μm particles and to distinguish between 1μm and 10μm particles.

year: 2012

title: The southern initiative: How indigenous values inspire social innovation and impact

authors: Niu, Xiaoliang

abstract: Indigenous values are increasingly recognised in helping organisations contribute to wellbeing within and beyond the workplace. Adopting the theoretical lens of Māori economies of wellbeing, this case study examines how The Southern Initiative (TSI), a unit within Auckland Council, incorporates Māori values to co-create place-based solutions and foster whānau (family) wellbeing. Through kōrero (conversations) with three people, a wānanga (collaborative discussion) with TSI members, and analysis of organisational literature, we identified how TSI's organising approach synthesises social innovation and bureaucracy. We found that indigeneity-embedded intrapreneurship, distributed leadership, and whānau-centred design support TSI's innovations. Mana (prestige) emerged as a primary organising principle, sustaining TSI's approach to achieving systemic change. By bridging Indigenous paradigms and conventional managerial practice, this case study demonstrates how Māori values can transform public sector management, elevate social justice, and encourage community resilience. These findings highlight culturally grounded frameworks for delivering social impact and shaping equitable outcomes.

text: The southern initiative: How indigenous values inspire social innovation and impact Indigenous values are increasingly recognised in helping organisations contribute to wellbeing within and beyond the workplace. Adopting the theoretical lens of Māori economies of wellbeing, this case study examines how The Southern Initiative (TSI), a unit within Auckland Council, incorporates Māori values to co-create place-based solutions and foster whānau (family) wellbeing. Through kōrero (conversations) with three people, a wānanga (collaborative discussion) with TSI members, and analysis of organisational literature, we identified how TSI's organising approach synthesises social innovation and bureaucracy. We found that indigeneity-embedded intrapreneurship, distributed leadership, and whānau-centred design support TSI's innovations. Mana (prestige) emerged as a primary organising principle, sustaining TSI's approach to achieving systemic change. By bridging Indigenous paradigms and conventional managerial practice, this case study demonstrates how Māori values can transform public sector management, elevate social justice, and encourage community resilience. These findings highlight culturally grounded frameworks for delivering social impact and shaping equitable outcomes.

year: 2025