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

Abstract

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.

Biofilms from a Brazilian water distribution system include filamentous fungi

“…detected filamentous fungi on replaced pipes from the same water network as described in the present results, confirming that filamentous fungi are able to grow as biofilms on pipe surfaces. These findings corroborate Doggett (2000) and Sammon et al (2011) who also detected filamentous fungal biofilms in replaced pipes. Nagy and Olson (1985) emphasize that older pipes support a more diverse community composed of diverse microorganisms, including filamentous fungi.…”

“…Taylor et al (2001) identified 307 fungal species as emerging pathogens, and biofilms have been reported to contain some of these (WHO 2003). Nevertheless, reports of filamentous fungi in biofilms remain few and somewhat inconclusive (Doggett 2000;Kelley et al 2003;Sammon et al 2011;.…”

Vermamoeba vermiformis-Aspergillus fumigatus relationships and comparison with other phagocytic cells

“…Moreover, the A. fumigatus species has been found in hospital water samples (Araujo et al 2010;Hayette et al 2010). Consequently, as water-related activities could be a route of fungal transmission to the immunocompromised host (Anaissie et al 2002;Sammon et al 2011), the presence of V. vermiformis and A. fumigatus in hospital water could lead to an increase of nosocomial infections by this fungus.…”

Two rapid assays for screening of patulin biodegradation

“…Since patulin-producing Penicillium species also have been isolated from the marine environment (Vansteelandt et al 2012), it is not clear whether the water from apple packing houses is directly responsible for the contamination of drinking water. Airborne spores may play an important role in contamination of water reservoirs (Sammon et al 2011). Many different species of Penicillium are known to produce patulin.…”