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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.

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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.

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To determine the potential for intra-oviductal contamination of sea turtle eggs with fungi accumulated during nesting, turtles were sampled for cloacal fungi. Pre-gravid females had a low incidence (17%) of cloacal fungi (Acremonium, Cladosporium, Penicillium). A higher occurrence (30%) of these same fungi in courting animals, that had not bred for ≥2 years, was probably the result of transfer during intromission. Nesting (75%) and inter-nesting (100%) turtles had the greatest occurrence and diversity of cloacal fungi (Acremonium, Aspergillus, Chrysosporium, Fusarium, Mucor, Penicillium, Phialophora, Sporothrix, Stachybotrys). The incidence of cloacal fungi rapidly decreased after nesting, to 28% within one year (Acremonium, Penicillium) and 13% in animals that bred at least two years earlier (Acremonium, Cladosporium, Penicillium). The other species of fungi are probably lost during defaecation.If fungal spores can be transported and maintained in the sea turtle oviduct by the same mechanisms as for spermatozoa, acute intra-seasonal contamination of eggs by fungi may be possible. The potential for chronic inter-seasonal contamination of the oviduct appears to be low.

White clover mosaic virus infection of Ladino clover seedlings resulted in decreased plant weight and a 71 % decrease in the number of nodules per plant without the decrease in nodule size which is usually observed when legumes are virus-infected. Nodule numbers decreased both on plants nodulated with an effective strain and on those with an ineffective strain of Rhizobium.

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