Papers by Christopher Saint
Fine-tuning the Surface of Forward Osmosis Membranes via Grafting Graphene Oxide: Performance Patterns and Biofouling Propensity
ACS Applied Materials & Interfaces, 2015
Graphene oxide (GO) nanosheets were attached to the polyamide selective layer of thin film compos... more Graphene oxide (GO) nanosheets were attached to the polyamide selective layer of thin film composite (TFC) forward osmosis (FO) membranes through a poly l-Lysine (PLL) intermediary using either layer-by-layer or hybrid (H) grafting strategies. Fourier transform infrared spectroscopy, zeta potential, and thermogravimetric analysis confirmed the successful attachment of GO/PLL, the surface modification enhancing both the hydrophilicity and smoothness of the membrane's surface demonstrated by water contact angle, atomic force microscopy, and transmission electron microscopy. The biofouling resistance of the FO membranes determined using an adenosine triphosphate bioluminescence test showed a 99% reduction in surviving bacteria for GO/PLL-H modified membranes compared to pristine membrane. This antibiofouling property of the GO/PLL-H modified membrane was reflected in reduced flux decline compared to all other samples when filtering brackish water under biofouling conditions. Further, the high density and tightly bound GO nanosheets using the hybrid modification reduced the reverse solute flux compared to the pristine, which reflects improved membrane selectivity. These results illustrate that the GO/PLL-H modification is a valuable addition to improve the performance of FO TFC membranes.
Optimising diet decisions and urban agriculture using linear programming
Food Security, 2014
ABSTRACT Amidst continual global population growth, land degradation and climate change, consumer... more ABSTRACT Amidst continual global population growth, land degradation and climate change, consumers are becoming more aware of the environmental impact of their diet. People in cities are also looking to mitigate the risk of disruption to their food supply through adoption of urban agriculture (UA). It is not at all clear, however, what impact UA will ultimately have on urban food security. The informal nature of many UA enterprises makes quantification difficult, and some projections of cities “feeding themselves” appear to simply reflect untested optimism. This paper demonstrates the novel use of Linear Programming (LP) to explore different dietary preferences (high meat intake versus vegetarian), and to determine the feasibility of urban agriculture (UA) making a substantial contribution to food security. The model quantifies the maximum potential impact of locally-grown produce in terms of either reducing cost or maximising the dietary contribution. Results show that LP can be used effectively to explore optimal cropping on urban land, based on the amount of available land per capita. A key finding of this feasibility study is that the contribution of UA to realistic diets—while limited—need not be trivial. In our case study of Northern Adelaide, Australia, it appears that 10–15 % of dietary protein could be produced in a typical suburban backyard, with or without chicken meat, along with savings of around AU$1 per person per day. Both the nature of the optimal UA crop regime and its impact are shown to depend on the dietary context, especially the level of meat consumption.
Legionella longbeachae isolated from water
The Medical journal of Australia, Jan 19, 1998
Journal of general microbiology, 1990
A restriction endonuclease map was derived for the aromatic amine and m-toluate catabolic plasmid... more A restriction endonuclease map was derived for the aromatic amine and m-toluate catabolic plasmid pTDN1 present in Pseudomonas putida UCC22, a derivative of P. putida mt-2. The plasmid is 79 +/- 1 kbp in size and can be divided into a restriction-site-deficient region of 51 +/- 1 kbp and a restriction-site-profuse region of 28 kbp which begins and ends with directly repeating sequences of at least 2 kbp in length. A mutant plasmid isolated after growth of the host on benzoate had lost the restriction-profuse region by a straightforward recombinational loss retaining one copy of the direct repeat. Analysis of clones, deletion and Tn5 insertion mutants strongly suggested that the meta-cleavage pathway of pTDN1 was situated in the region readily deleted. The catechol 2,3-dioxygenase (C23O) gene of pTDN1 showed no hybridization or restriction homology to previously described C23O genes of TOL plasmids pWW0 and pWW15. In addition, there was little homology between intact pTDN1, pWW0 and ...
Water research, 2009
Biologically active sand filters within water treatment plants (WTPs) are now recognised as an ef... more Biologically active sand filters within water treatment plants (WTPs) are now recognised as an effective barrier for the removal of geosmin. However, little is known regarding the actual microbiological processes occurring or the bacteria capable of degrading geosmin. This study reports the enrichment and isolation of a Gram-negative bacterium, Geo48, from the biofilm of a WTP sand filter where the isolate was shown to effectively degrade geosmin individually. Experiments revealed that Geo48 degraded geosmin in a planktonic state by a pseudo-first-order mechanism. Initial geosmin concentrations ranging from 100 to 1000ng/l were shown to directly influence geosmin degradation in reservoir water by Geo48, with rate constants increasing from 0.010h(-1) (R(2)=0.93) to 0.029h(-1) (R(2)=0.97) respectively. Water temperature also influenced degradation of geosmin by Geo48 where temperatures of 11, 22 and 30 degrees C resulted in rate constants of 0.017h(-1) (R(2)=0.98), 0.023h(-1) (R(2)=0....
The "Nostocoida limicola" story: resolving the phylogeny of this morphotype responsible for bulking in activated sludge
Water science and technology : a journal of the International Association on Water Pollution Research, 2002
On the basis of 16S rRNA sequence analyses of several isolates of "Nostocoida limicola"... more On the basis of 16S rRNA sequence analyses of several isolates of "Nostocoida limicola" from activated sludge plants in Australia and other countries, it is clear that "N. limicola" I, II and III are not three morphological variants of a single bacterium but at least three phylogenetically different bacteria. Data show that "N. limicola" I are members of at least two genera in the low mol% G+C gram-positive bacteria, while some isolates of "N. limicola" II belong to the high mol% G+C gram positive bacteria, and "N. limicola" III is a member of the Planctomycetales. Design and application of 16S rRNA targeted probes for each to biomass samples suggests that their phylogeny is more diverse than pure culture studies would suggest.
International journal of systematic and evolutionary microbiology, 2001
Five strains of the filamentous bacterium 'Nostocoida limicola' III were successfully iso... more Five strains of the filamentous bacterium 'Nostocoida limicola' III were successfully isolated into pure culture from samples of activated sludge biomass from five plants in Australia. 16S rRNA gene sequence analyses showed that all isolates were members of the Planctomycetales, most closely related to Isosphaera pallida, but they differed phenotypically from this species in that they did not glide and were not thermotolerant. The ultrastructure of these 'N. limicola' III isolates was also consistent with them being Planctomycetales, in that they possessed complex intracellular membrane systems compartmentalizing the cells. However, the arrangements of these intracellular membranes differed between isolates. These data confirm that 'N. limicola' III is phylogenetically unrelated to both 'N. limicola' I and 'N. limicola' II, activated sludge filamentous bacteria which share morphological features in common with 'N. limicola' III and whi...
Conservation of a pseudomonad-like hydrocarbon degradative ferredoxin oxygenase complex involved in rhizopine catabolism in Sinorhizobium meliloti and Rhizobium leguminosarum bv. viciae
Journal of molecular microbiology and biotechnology, 2000
In Sinorhizobium meliloti the mocCABR genes have previously been shown to be required for rhizopi... more 
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Papers by Christopher Saint