Recent investigations on water microbiology have shown that most of the biomass present
in the drinking water network is located at the pipe walls as biofilms. Biofilms are organized
in highly efficient and stable ecosystems and can be viewed as a survival mechanism; this way
of life can provide protection from chemical, biological or physical stresses. Moreover,
biofilms play a major role in the accumulation, protection and dissemination of pathogens
through water distribution systems. Although filamentous fungi are especially adapted for
growth on surfaces, fungal water biofilms have received less attention when compared with
bacterial biofilms, thus remaining a lack of information in this field. The use of microscopy
techniques associated with image analyses has become a valuable tool for in situ studies.
Fluorescent in situ hybridization (FISH) and fluorescent dyes are non-invasive and nondestructive
techniques which provide information on cell morphology, metabolism and
phylogeny. In this work, we aimed to detect filamentous fungal biofilm in a water distribution
system using FISH (EUK516 and FUN1429 probes) and Calcofluor staining in replaced pipes.
We also presented a sampler developed to study in situ fungal biofilms formation in water
distribution system. Calcofluor staining was a rapid and easy method to detect filamentous
biofilms on pipes surfaces. Additionally, FISH provided phylogenetic information by the
detection of eukaryotic and fungal cells. Ours results contributed to demonstrate the
presence of fungi in water biofilms and emphasised that fungi play an important role in water
biofilms and microbial water quality
