Fungi represent a considerable challenge given their
ubiquitous
inhabitation and growth in drinking water distribution systems (DWDSs),
yet the germination behavior of fungal spores in DWDSs is largely
unknown. This study investigated germination of three chlorine-resistant
fungal spores (Penicillium chrysogenum, Cladosporium halotolerans, and Penicillium spinulosum) in synthetic tap water (STW)
under varying conditions of disinfectants (free chlorine, FC; monochloramine,
NH2Cl), humic acid (HA), and pH. The germination ratios
of the tested fungal spores in STW(+HA) were <10% without FC/NH2Cl, while surprisingly increased to a maximum of 67.5% and
44.14% with 2 mg/L FC and 0.4 mg/L NH2Cl, respectively,
for C. halotolerans spores. With increasing
initial concentrations of FC (0–4 mg/L) and NH2Cl
(0–2 mg/L), germination ratios of C. halotolerans spores in STW+HA showed a first increasing and then decreasing trend,
suggesting that the stimulation effect was outweighed by inactivation
at high CT values. Nontargeted metabolomics analysis identified the
decrease of several potential self-inhibitors for spore germination
by chlor(am)ination. Patterns of significantly changed metabolites
and pathways involving lipid, sugar, and amino acid metabolism were
significantly different for C. halotolerans spores treated by FC versus NH2Cl. The results provide
new insights into survival strategies and germination mechanisms of
fungal spores in chlor(am)ine-disinfected DWDSs.