Microfungi in Drinking Water: The Role of the Frog Litoria caerulea

Microfungi were recovered from all parts of a municipal water distribution system in sub-tropical Australia even though virtually no colony-forming units were recovered from the treated water as it left the treatment plant. A study was then undertaken to determine the potential sources of the microfungal population in the distribution system. Observation of frogs (Litoria caerulea) using the internal infrastructure of a reservoir as diurnal sleeping places, together with observation of visible microfungal growth on their faecal pellets, led to an investigation of the possible involvement of this animal. Old faecal pellets were collected and sporulating fungal colonies growing on their surfaces were identified. Fresh faecal pellets were collected and analysed for microfungal content, and skin swabs were analysed for yeasts. It was found that the faeces and skin of L. caerulea carried large numbers of yeasts as well as spores of various filamentous fungal genera. While there are many possible sources of microfungal contamination of municipal drinking water supplies, this study has revealed that the Australian green tree frog L. caerulea is one of the important sources of filamentous microfungi and yeasts in water storage reservoirs in sub-tropical Australia where the animal is endemic

Three Potential Sources of Microfungi in a Treated Municipal Water Supply System in Sub-Tropical Australia

Some microfungi are known to be opportunistic human pathogens, and there is a body of scientific opinion that one of their routes of infection may be water aerosols. Others have been implicated as causative agents of odours and off-tastes in drinking water. This study was undertaken to investigate three potential sources of microfungi in a treated, oligotrophic municipal water supply system in sub-tropical Australia. Formation of the microfungal component of developing biofilm on hard surfaces in water storage reservoirs was also assessed. Inside and outside air samples were collected from two reservoirs using two types of Burkard air samplers. Biofilm and soft sediment samples were collected from the inner surfaces of asbestos cement water pipes and from pipe dead ends respectively. These were analysed for microfungal growth and sporulation using Calcofluor White stain and epifluorescent microscopy. Artificial coupons of glass, PVC and concrete were immersed in two reservoirs to assess microfungal biofilm formation. This was analysed periodically using Calcofluor White stain and epifluorescent microscopy, cultures of coupon swabs and scanning electron microscopy. Fungal spores were recovered from all air samples. The number of colonies and the genera were similar for both inside and outside air. Microfungal filaments and sporulating structures were recovered from most of the pipe inner surface biofilm and dead end sediment samples, but were sparser in the biofilm than in the sediment samples. No recognisable, vegetative filamentous fungi were found in the slowly developing biofilm on coupons. This study indicates that airborne spores are an important potential source of microfungi found in water storage reservoirs. It has also demonstrated conclusively that filamentous microfungi grow and sporulate on water pipe inner surfaces and in soft sediments within the water distribution system

Incidence and Distribution of Microfungi in a Treated Municipal Water Supply System in Sub-Tropical Australia

Drinking water quality is usually determined by its pathogenic bacterial content. However, the potential of water-borne spores as a source of nosocomial fungal infection is increasingly being recognised. This study into the incidence of microfungal contaminants in a typical Australian municipal water supply was carried out over an 18 month period. Microfungal abundance was estimated by the membrane filtration method with filters incubated on malt extract agar at 25 °C for seven days. Colony forming units were recovered from all parts of the system and these were enumerated and identified to genus level. The most commonly recovered genera were Cladosporium, Penicillium, Aspergillus and Fusarium. Nonparametric multivariate statistical analyses of the data using MDS, PCA, BEST and bubble plots were carried out with PRIMER v6 software. Positive and significant correlations were found between filamentous fungi, yeasts and bacteria. This study has demonstrated that numerous microfungal genera, including those that contain species which are opportunistic human pathogens, populate a typical treated municipal water supply in sub-tropical Australia

The taxonomy and ecology of cylindrospermopsin producers in Australia

In the 1970s initial data came from Australia in relation to the presence of straight Cylindrospermopsis raciborskii in two dams, the Solomon Dam, Palm Island and North Pine Dam near Brisbane. However, following the loss of macrophytes, floods and fish releases into various riverine impoundments, this species was identified in both the Murray Darling and Fitzroy River systems by 1991. Various coiled and straight morphotypes were documented. The ecology of Cylindrospermopsis in riverine impoundments was analyzed in the 1990s with emphasis upon the prediction of bloom formation and delimitation of growth conditions. It germinated when the temperature of the sediment water interface was 23º C, dominated in conditions of low nutrient concentrations in the epilimnion 1 to 3 ugL-1 then formed akinetes and disappeared from the water column just prior to flood events. Cultures of Cylindrospermopsis from various tropical and temperate regions of Australia were used to investigate the genetics of various morphotypes, germination of akinetes and toxin breakdown, bacteria responsible for toxin breakdown, toxin production under various conditions, bioaccumulation of cylindrospermopsin in both plants and animals and grazing by ciliates. More recently, Aphanizomenon ovalisporum and Lyngbya wollei Plectonema wollei have been identified as cylindrospermopsin producers. Dams and pipelines with alternating dominance of Aphanizomenon ovalisporum and Cylindrospermopsis raciborskii have recently been found and are currently being studied in relation to the ecology, toxicity taxonomy and genetics of these species

Blue-green algae present and future /

On a yearly basis since September 1989, the residents of Rockhampton have known of blue-green algal blooms in the Fitzroy River Barrage. These have ranged from small populations of species causing taste and odour problems, to toxic blooms which have posed a serious risk to human health. Blooms have also been detected at Rannes, Moura Weir and Theresa Creek Dam. As many local forms of blue-green algae do not form the surface scums characteristic of southern material, the extent of the problem is not readily comprehended. This paper will cover some of the cyanobacteria (bluegreen algae) which are known to be present in the Fitzroy River catchment, the problems we face with turbid waters and nutrient levels higher than those of the Central and Northwestern Rivers of New South Wales, and a climate and riverine chemistry which predispose this region to cyanobacterial doninance and bloom formation. The future benefits of flow releases will be considered along with potential problems

Pediastrum wintonense sp.nov. (Chlorophyceae, Neochloridales, Hydrodictyaceae) from Lake Mokoan, north-east Victoria, and Lake Elphinstone, Queensland

Pediastrum wintonense sp. nov. (Chlorophyceae, Neochloridales, Hydrodictyaceae) is described from turbid Lake Mokoan, north-east Victoria, and recorded also from Lake Elphinstone in the north-west of the Fitzroy River catchment in Queensland. The occurrence of lP. wintonense as a minor component of the plankton within the two lakes is documented, and it is described from a shoreline accumulation of up to 900000 colonies/ml in Lake Mokoan

A guide to the identification of common blue-green algae (Cyanoprokaryotes) in Australian freshwaters

Blue-green algae (Cyanophyta) or cyanobacteria are prokaryotic phototrophic organisms. They have traditionally been classified with algae under the International Code of Botanical Nomenclature

A guide to the identification of common blue-green algae (Cyanoprokaryotes) in Australian freshwaters

Blue-green algae (Cyanophyta) or cyanobacteria are prokaryotic phototrophic organisms. They have traditionally been classified with algae under the International Code of Botanical Nomenclature

Profile of a bloom of the Cyanobacterium Cylindrospermopsis raciboarkii (Woloszynska) Seenaya and Subba Raju in the Fitzroy River in tropical Central Queensland

The physical, chemical and biotic conditions before and during a bloom of predominantly coiled heterocystous C. raciborskii are described. Initial increases in the population of this species were associated with windy days and the first downward movement of the thermocline into an anoxic hypolimnion after an extended period of stable stratification and no flow. Exponential growth and bloom formation coincided with the amval and retention of first wet-season inflows into the river impoundment. Cyanobacteria and rotifers dominated the planktonic assemblage and chytrids (cyanobacterial pathogens) were present when the cell density of cyanobacteria peaked. Grazing of the coiled forms that dominated during the bloom was not recorded, but the rotifer Brachionus angularis has been observed ingesting entire straight trichomes of C. raciborskii

Spatial and temporal variability in cyanobacterial populations controlled by physical processes

The Fitzroy impoundment is a long slender water body (10 m deep) formed by the regulation of the Fitzroy River in tropical Australia. Large, monsoonally driven discharges in late summer flush the impoundment repeatedly leaving, after 2 months, a longitudinally uniform, well-mixed water column, rich in dissolved nutrients and with high turbidity. For the rest of the year flows are negligible. Paradoxically, two sites with initially identical nutrient and stratification characteristics, and located only 30 km apart, develop quite different patterns of cyanobacterial succession. The upstream site is initially dominated by Anabaena circinalis which appears in early spring and collapses within the month. A mixed population of Anabaenopsis elenkinii and Aphanizomenon issatschenkoi then develops at both sites. This is followed by a mixture of small cyanobacteria (consisting of Cylindrospermopsis, Planktolyngbya and Limnothrix) which develops mainly at the downstream site and persists for 3 months until flushed away by flood flows. We report on data covering an 8 month period of investigation of the stratification, light climate, temperature and nutrient dynamics at these two sites. We show that large-scale climatic conditions and the local weather pattern set the physical and chemical conditions which determine the cyanobacterial response