Peter Cox

rRNA Sequences and Evolutionary Relationships among Toxic and Nontoxic Cyanobacteria of the Genus Microcystis

A primary-structure analysis of the 16S rRNA gene was performed with 10 strains representing five described and one unidentified species of the genus Microcystis. The phylogenies determined illustrate the evolutionary affiliations among Microcystis strains, other cyanobacteria, and related plastids and bacteria. A cluster of 10 strains that included hepatotoxic isolates identified as Microcystis aeruginosa formed a monophyletic group. However, the genus Microcystis appeared to be polyphyletic and contained two strains that clustered with unicellular cyanobacteria belonging to the genus Synechococcus. The clustering of related Microcystis strains, including strains involved in the production of the cyclic peptide toxin microcystin, was consistent with cell morphology, gas vacuolation, and the low G + C contents of the genomes. The Microcystis lineage was also distinct from the lineage containing the unicellular genus Synechocystis and the filamentous, heterocyst-forming genus Nostoc. The secondary structure of a Microcystis 16S rRNA molecule was determined, and genus-specific sequence signatures were used to design primers that permitted identification of the potentially toxic cyanobacteria belonging to the genus Microcystis via DNA amplification.

Concentrations of Pathogens and Indicators in Animal Feces in the Sydney Watershed

ABSTRACT A fecal analysis survey was undertaken to quantify animal inputs of pathogenic and indicator microorganisms in the temperate watersheds of Sydney, Australia. The feces from a range of domestic animals and wildlife were analyzed for the indicator bacteria fecal coliforms and Clostridium perfringens spores, the pathogenic protozoa Cryptosporidium and Giardia, and the enteric viruses adenovirus, enterovirus, and reovirus. Pathogen and fecal indicator concentrations were generally higher in domestic animal feces than in wildlife feces. Future studies to quantify potential pathogen risks in drinking-water watersheds should thus focus on quantifying pathogen loads from domestic animals and livestock rather than wildlife.

Specific Amplification and Restriction Polymorphisms of the Cyanobacterial rRNA Operon Spacer Region

Summary Forty-two strains of cyanobacteria commonly associated with toxic bloom events and representing 10 cyanobacterial genera were examined by RFLP analysis of the PCR amplified 16S-23S rRNA gene internal transcribed spacer (ITS). A total of 97 different DNA profiles were generated by the application of 8 restriction endonucleases to digest the PCR products. The length of the PCR products obtained for strains assigned to the same genus seemed to be a useful taxonomic character and could probably be used for rapid identification. Nine characteristic amplification products delineated the 10 genera studied. Intrageneric strain differentiation was provided by restriction digest profiles which, when combined for each strain, resulted in 27 distinct genotypes. Specific amplification of cyanobacterial strains from mixed populations and environmental samples containing algae and heterotrophic bacteria was possible due to the use of a cyanobacteria specific 16S rRNA gene-directed PCR primer. The genetic relatedness observed between the taxa studied coincided with the taxonomic identification of the studied strains, particularly within the genera Anabaena and Microcystis.

Genotypes of Cryptosporidium from Sydney water catchment areas

Aims:  Currently cryptosporidiosis represents the major public health concern of water utilities in developed nations and increasingly, new species and genotypes of Cryptosporidium are being identified in which the infectivity for humans is not clear. The complicated epidemiology of Cryptosporidium and the fact that the majority of species and genotypes of Cryptosporidium cannot be distinguished morphologically makes the assessment of public health risk difficult if oocysts are detected in the raw water supplies. The aim of this study was to use molecular tools to identify sources of Cryptosporidium from the Warragamba catchment area of Sydney, Australia.

Identification of zoonotic Cryptosporidium and Giardia genotypes infecting animals in Sydney's water catchments

To identify the animal sources for Cryptosporidium and Giardia contamination, we genotyped Cryptosporidium and Giardia spp. in wildlife from Sydneys water catchments using sequence analysis at the 18S rRNA locus for Cryptosporidium and 18S rRNA and glutamate dehydrogenase (gdh) for Giardia. A total of 564 faecal samples from 16 different host species were analysed. Cryptosporidium was identified in 8.5% (48/564) samples from eight host species and Giardia was identified in 13.8% (78/564) from seven host species. Eight species/genotypes of Cryptosporidium were identified. Five G. duodenalis assemblages were detected including the zoonotic assemblages A and B.

16S Ribosomal RNA Gene Sequence and Phylogeny of Toxic Microcystis sp. (Cyanobacteria)

The toxigenic and bloom-forming cyanobacterial genus Microcystis contains several ill-defined species. The 16S rDNA for two strains of toxic M. aeruginosa were sequenced and compared to available cyanobacterial, bacterial, and chloroplast 16S rRNA gene information. Phylogeny and the validity of a molecular taxonomy for the genus Microcystis is presented.

A novel method of extracting plasmid DNA from Helicobacter species.

Plasmids are extra‐chromosomal DNA that may encode products that aid in virulence, pathogenesis, and the spread of antibiotic resistance among a wide spectrum of bacteria. Plasmids have been detected in Helicobacter pylori, H. felis, H. fennelliae, and H. cinaedi. However, no function has been attributed to the Helicobacter plasmids studied to date. Moreover, the characterization of plasmids in other Helicobacter species is an as yet unexplored area of research. Several laboratories have reported difficulties in the extraction and isolation of plasmid DNA from H. pylori and H. felis isolates due to the presence of large amounts of DNase, necessitating cumbersome and time‐consuming purification steps. The development of a method for extracting plasmid DNA from Helicobacter species would be useful for future systematic studies of plasmids in this important group of microorganisms.

The Risk of Cryptosporidium to Sydney's Drinking Water Supply

Publisher Summary To protect the quality of drinking water in Sydney, the Sydney Water Corporation (SWC) and the recently created Sydney Catchment Authority (SCA) have adopted a catchment to customer risk management approach after the Cryptosporidium water crisis in 1998. In Sydney such an approach involves close collaboration with the New South Wales Department of Health (NSW Health), as well as the consortia managing several of Sydneys large water filtration plants (WFPs) under Build-Own-Operate (BOO) contracts. This chapter presents a paper, which aims to provide an update of the main actions that have been taken since the water crisis in Sydney in 1998. These updates need to be in: the catchments, water treatment plants, distribution system, and analytical laboratories for Cryptosporidium analysis.