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An evaluation of Australian escott natural Zeolites to isolate bacteria and viruses from water

Davies, Linda (2015) An evaluation of Australian escott natural Zeolites to isolate bacteria and viruses from water. PhD thesis, Murdoch University.

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Assessment of public health risk due to waterborne disease is delayed by the inability to rapidly isolate microorganisms from water for their detection. Australian Escott natural zeolites (natural zeolitized tuffs - NZs), modified by either a silanisation (SZ) or surfactant modification (SMZ) procedure were investigated to rapidly isolate Escherichia coli, Enterococcus faecalis and bacteriophage MS2 from water. It was hypothesised that microorganisms would bind to the NZ’s added as a powder with particle size <75 μm to water, be separated by sedimentation and detected by culture or molecular-based assays. Binding to the NZ’s was fast (within 10 minutes) and the NZ-microorganism complex was easily separated by sedimentation. However, microorganism isolation varied in different water chemistries and with different chemical modification of NZ surfaces. Isolation by SMZ, which had been described previously, was achieved at low levels (less than 10%) presumably because chemical inactivation prevented microorganism detection. For SZ, more than 60% of bacteria and 30% of MS2 bacteriophage (seeded at 103 cfu or pfu/ml) were isolated and detected after agitation in various solutions and in rainwater, bottled water and seawater. Selective isolation of E. faecalis was also enhanced using a novel phage endolysin recombinant protein attached to SZ, increasing isolation to greater than 85%. Furthermore, pyrosequencing analysis revealed that SZ isolated the most representative population of environmental bacteria from rainwater compared to SMZ and NZ. The process of isolation to detection was completed within three hours and did not require electricity, making NZ-isolation practical for field-based applications. The main drawback was lack of sensitivity as consistent isolation of very low numbers of microorganisms in water (< 102 cfu or pfu/ml) was not achieved. Nonetheless the isolation of live bacteria and viruses by SZ is a novel approach and could potentially be used in combination with molecular-based assays to detect waterborne pathogens.

Publication Type: Thesis (PhD)
Murdoch Affiliation: School of Health Professions
Supervisor: Ryan, Una
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